Synthesis, characterization and morphological studies of some novel siloxane-based block copolymeric materials containing organometallic as well as organic polyesteramides

Article abstract of DOI:10.1016/j.jorganchem.2013.08.002

A series of semi-aromatic diamine monomers (1,m-bis (4-amino benzoyloxy) alkanes; m = 2-6) having in-built ester linkages with variable methylene spacers were synthesized in two steps from aliphatic diols and p-nitrobenzoyl chloride and characterized by their melting points, elemental analysis, FTIR, ¹H and ¹³C NMR spectroscopic studies. The diamines were then polymerized in-situ with ferrocene-based organometallic and terephthaloyl- as well as isophthaloyl-based organic acyl chlorides along with telechelic polydimethylsiloxane oligomer to produce a novel set of ferrocene-containing siloxane-based block copolymers and their organic analogues. The corresponding polyesteramides of the synthesized copolymers, without siloxane segment, were also prepared for comparative studies. The structural features of the organometallic and organic block copolymers along with their respective polyesteramides were confirmed by their physical properties and spectroscopic studies. The molecular parameters of all these materials were determined by static laser light scattering (LLS) technique and glass transition temperatures (T_g) were obtained by differential scanning calorimetry (DSC). The materials were soluble in sulphuric acid and partially soluble in common organic solvents at room temperature, yet become readily soluble upon N-trifluoroacetylation. The morphological information of the synthesized materials was obtained by X-ray diffraction and surface studies (SEM and AFM).

Full text of DOI:10.1016/j.jorganchem.2013.08.002

Journal of Organometallic Chemistry 745-746 (2013) 312e328
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis, characterization and morphological studies of some novel
siloxane-based block copolymeric materials containing
organometallic as well as organic polyesteramides
,
b,
Muhammad Saif Ullah Khan a, Zareen Akhter a , Naseer Iqbal c, Mohammad Siddiq a
*
a Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
b Institute of Analytical and Food Chemistry, University of Vienna, Vienna, Austria
c COMSATS Institute of Information Technology (CIIT), Lahore, Pakistan
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of semi-aromatic diamine monomers (1,m-bis (4-amino benzoyloxy) alkanes; m ¼ 2e6) having
Received 15 May 2013
Received in revised form
24 July 2013
in-built ester linkages with variable methylene spacers were synthesized in two steps from aliphatic
diols and p-nitrobenzoyl chloride and characterized by their melting points, elemental analysis, FTIR, 1
H
and 13C NMR spectroscopic studies. The diamines were then polymerized in-situ with ferrocene-based
organometallic and terephthaloyl- as well as isophthaloyl-based organic acyl chlorides along with tel-
echelic polydimethylsiloxane oligomer to produce a novel set of ferrocene-containing siloxane-based
block copolymers and their organic analogues. The corresponding polyesteramides of the synthesized
copolymers, without siloxane segment, were also prepared for comparative studies. The structural fea-
tures of the organometallic and organic block copolymers along with their respective polyesteramides
were confirmed by their physical properties and spectroscopic studies. The molecular parameters of all
these materials were determined by static laser light scattering (LLS) technique and glass transition
temperatures (Tg) were obtained by differential scanning calorimetry (DSC). The materials were soluble
in sulphuric acid and partially soluble in common organic solvents at room temperature, yet become
readily soluble upon N-trifluoroacetylation. The morphological information of the synthesized materials
was obtained by X-ray diffraction and surface studies (SEM and AFM).
Accepted 4 August 2013
Keywords:
Organometallic polyesteramides
Block copolymers
Trif1luoroacetylation
Molecular parameters
Moisture absorption
Surface morphology
Ó 2013 Elsevier B.V. All rights reserved.
1. Introduction
energy [3,4]. These polymeric systems are generally prepared by
the incorporation of rigid structural segments such as polyamides,
Polymer science has developed rapidly into an exciting area of
high-tech materials research over the last few decades [1,2]. A
major contribution to this transformation has been the infusion of
creative ideas from synthetic organic chemists [1,2]. Block co-
polymers, which comprise two chemically dissimilar bonded
polymer segments, are considered as an attractive category of
polymeric materials because they combine the properties of both
the parent polymers and offer the possibility of tailoring the
physico-chemical and thermo-mechanical properties along with
processability to obtain new engineering materials [3,4]. Siloxane-
containing block copolymers, principally based on poly-
dimethylsiloxane (PDMS), are particularly interesting because of
the advantageous properties which include oxidative resistance,
good biocompatibility, main chain flexibility and low surface
polyimides or polysulfones adjacent to the flexible siloxane units
and can be utilized in many applications as specialized materials,
such as gas separation membranes, biomaterials, photoresists,
protective coatings, elastomers and emulsifiers [4,5]. Poly-
condensation is the most versatile technique for the synthesis of
such copolymers. This is mainly due to the availability of a wide
variety of well-defined reactive telechelic siloxane oligomers [3e5].
Polyesteramides are receiving much attention these days
because these polymers may offer an interesting combination of
properties: a high degradability caused by the ester linkages and
good thermo-mechanical properties caused by the establishment
of hydrogen bonds between amide groups [5e8]. These are of in-
terest because of their excellent heat resistant and gas barrier
properties [7] and have found a wide range of applications, such as
disposable bags, agricultural films, drug carriers or matrix resins for
biomedical materials [8,9].
Polyesteramides are generally prepared bysolution, interfacial or
melt polycondensation of diacids or their derivatives with amino
* Corresponding author. Tel.: þ92 51 90642111; fax: þ92 51 90642241.
E-mail address: zareenakhter@yahoo.com (Z. Akhter).
0022-328X/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2013.08.002

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
313
hydroxy compounds employing several condensing agents, such as
thionyl chloride, diphenyl chlorophosphate, tosyl chloride and N-
methyl imidazole [6e10]. However, the polycondensation reactions
of diacid chlorides with aminophenols, diphenols or diamines con-
taining preformed amide and ester groups have also been applied
successfully for their synthesis [6e11]. Among different monomers
utilized for the preparationof high-performance polymers, aromatic
diamines are valuable building blocks which can induce desired
modifications in the chemical nature of the macrochain [12e16].
Various rotatable segments such as ester group [12,13], ether moiety
[14], sulfone linkage [15], methylene spacers [16], etc. can be intro-
duced into the polymer backbones by structural modification of the
diamine monomers. These flexible linkages increase the degree of
freedom by reducing the segmental barrier and effectively disrupt
the potential intermolecular interactions and thus enhance the
solubility and processability of the resulting polymers [12e16].
The properties of the polymers can be modified by the incor-
poration of metals into their core structure [17]. The strategy can be
useful in obtaining qualified polymeric materials with unusual and
fascinating characteristics as there is great potential in combining
the attributes of flexibility, versatility and solubility of the organic
groups with the magnetic, electrical and optical properties of the
metal [17,18]. Ferrocene entity, owing to its excellent thermal and
photochemical stability as well as the unique and valuable redox
behaviour, is an attractive scaffold for incorporating metal into
polymeric structure [18]. Ferrocene-based polymers and co-
polymers are useful for a broad spectrum of applications, e.g.
manufacture of electronic devices such as microelectrochemical
diodes [19], formation of redox gels with charge transfer properties
[20], for modification of electrodes [21], construction of ampero-
metric biosensors [22], as precursors to ferromagnetic ceramics
[23], in medical applications for cancer treatment [24] and also in
the area of non-linear optical (NLO) materials [25].
Keeping in view the escalating performance characteristics
demanded by block copolymers to meet the requirements of mod-
ern technological applications, the present study deals with a one-
pot two-step synthesis of some novel polydimethylsiloxane-based
hetero-atomic block copolymers containing ferrocene-based
organometallic polyesteramides and their terephthaloyl- as well
as isophthaloyl-based organic analogues using solution poly-
condensation technique. The corresponding polyesteramides of the
synthesized block copolymers, without siloxane segment, were also
prepared forcomparison of properties. The diamine monomers used
in the present work were of the general formulae; 1,m-bis(4-amino
benzoyloxy)alkanes with variable aliphatic character (m ¼ 2e6) and
pre-formed esterlinkages. The soft polydimethylsiloxane block used
was of relatively higher molecular weight. It is believed that the
properties of siloxane-based polymers can be tailored by merely
changing the block length and/or the molecular weight of the
siloxane oligomer[3,4,26]. Theresultingorganometallic materials as
well as the organic analogues were characterized by various
analytical techniques in order to elucidate their structures and
explore their properties with respect to applications. These harde
soft polymers are expected to combine the advantageous properties
of the parent polymers along with interesting new properties which
enable them to be applicable in a numberof technological fields such
as layer by layer deposition of films for gas separation membranes,
protective layers and also in biological applications [27e29].
chloride, 4-nitrobenzoic acid, ethylene glycol, 1,3-propane diol, 1,4-
butane diol, 1,5-pentane diol, 1,6-hexane diol, triethyl amine and
10% palladium on charcoal (Pd/C) were purchased from Fluka
Chemie GmbH, Switzerland, and used without further purification.
Anhydrous potassium carbonate, hydrazine monohydrate and thi-
onyl chloride were obtained from Merck KGaA, Germany, and used
as received. Bis (3-aminopropyl)-terminated polydimethylsiloxane
(PDMS) H2N(CH2)3(Me2SiO)y(CH2)3NH2 (y ¼ 360), terephthaloyl
chloride, isophthaloyl chloride and sodium hypochlorite solution
(10%) were obtained from SigmaeAldrich Chemie GmbH, Germany.
Ethanol, N,N0-dimethyl formamide (DMF) and tetrahydrofuran
(THF) were procured from Riedel-de Haën AG, Germany; toluene
was obtained from Panreac Química S.L.U. Spain; and m-cresol and
n-hexane were purchased from Fluka Chemie GmbH, Switzerland.
Dichloromethane, diethyl ether, dimethyl sulfoxide (DMSO) and
methanol were purchased from Merck KGaA, Germany. All solvents
were freshly dried and distilled prior to use. Unless stated other-
wise, all manipulations were conducted in an inert atmosphere
created by vacuum line and dry N2 gas. The progress of the re-
actions and purity of the products were monitored by thin layer
chromatography on pre-coated Kieselgel 60HF TLC plates.
2.2. Measurements
The elemental (C, H, N) analysis of the synthesized compounds
was performed using CHNS-932 LECO instrument. Melting tem-
peratures of the products were determined on a Mel-Temp.
(Mitamura Riken Kogyo.) apparatus using open capillary tubes
and are uncorrected. The solid state Fourier transform infrared
spectra were recorded on a Perkin Elmer Spectrum One (Ver. B)
FTIR Spectrophotometer using KBr pellets. 1H and 13C NMR spectra
were acquired with a Bruker 300 MHz ultrashield Spectropho-
tometer in appropriate solvent (DMSO-d6, CDCl3, THF-d8). The
effective field strength for 13C NMR spectra was 75 MHz. Weight-
average molar masses were determined on Brookhaven BI 200S
instrument fitted with an argon-ion laser (Coherent Innova) with
vertically polarized incident light of wavelength
l
¼ 637 nm and a
BI 9000 AT digital correlator. The refractive index increment (dn/
dC) values were determined by using a high precision differential
refractometer consisting of a laser light source, a position-sensitive
detector, and a temperature-controlled refractometer cuvette and
has wide linear detection range (ꢀ0.035 RI units) with a resolution
of 10ꢁ6 RI units, which is sufficient for determining the specific
refractive index increment of most polymer solutions [30]. All the
polymer solutions were clarified by a 0.45 mm millipore Teflon sy-
ringe filter prior to analysis. Water absorption studies were carried
out following the ASTM D570-81 procedure [31]. The samples were
placed in a vacuum oven at 80 ꢂC until they attained a constant
weight. These oven-dried pre-weighed samples (Wo) were then
soaked in water for 72 h at room temperature (28 ꢂC), dried by
contacting with absorbent paper and weighed again (Wf). The
percentage increase in weight of the sample was calculated by
using the formula: ((Wf ꢁ Wo)/Wo) ꢃ 100. Wide-angle XRD analysis
of the polymeric materials was carried out using a Philips 3040/60
X’Pert PRO diffractometer equipped with Cu-Ka radiation source.
SEM and EDX analysis of the polymer surfaces were carried out
using a JEOL JSM-6460 instrument coupled with Oxford EDS-7573.
Samples were mounted with Al stubs using double-sided adhesive
tapes and were coated with gold using a vacuum evaporator (JEOL-
420) to make the surfaces conducting. AFM images of the polymeric
materials were recorded on a Veeco Nanoscope IVa system in
contact mode with Veeco SNL-10 silicon tips with a spring constant
of 40 N mꢁ1 and an onset pressure corresponding to a differential
2. Experimental
2.1. Materials and methods
All chemicals and reagents used were of highest purity unless
otherwise mentioned. Ferrocene, aluminium chloride, acetyl
signal of 1 V on the photo diode. To obtain an image, 10
polymer materials were spin coated onto a sample disk and
mL of the

314
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
scanned with scan rates in the range 1e2 Hz at room temperature
(28 ꢂC). DSC analysis of the synthesized polymeric materials was
carried ouꢁt1using Mettler Toledo DSC 823e instrument at a rate of
10 ꢂC min in nitrogen atmosphere.
2.4.1.3. Preparation of 1,4-bis(4-nitrobenzoyloxy)butane (N-4).
1,4-Bis(4-nitrobenzoyloxy)butane (N-4) was synthesized by the
above mentioned procedure using 1,4-butane diol (1.19 ml;
13.47 mmol). Yield 84%, m.p. 168 ꢂC. Elemental analysis for
C
18H16N2O8 (MW ¼ 388) in wt% calc. C ¼ 55.67, H ¼ 4.12, N ¼ 7.21
2.3. Synthesis of ferrocene monomer
and found C ¼ 55.85, H ¼ 4.08, N ¼ 7.59. FTIR (KBr pellet) in cmꢁ1
:
3110, 3078 (w, CeH stretch Ar), 2944, 2854 (w, CeH stretch Al),
1718 (s, ester C]O stretch), 1606 (m, C]C stretch Ar), 1522, 1350 (s,
1,10-Diacetyl ferrocene and 1,10-ferrocene dicarboxylic acid were
synthesized as reported by Rosenblum and Woodward [32] and
Knobloch and Rauscher [33] respectively while 1,10-ferrocene
dicarbonyl chloride was prepared by an improved and efficient
method described already by our group [34].
NO2 stretch), 842 (m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d (ppm)
and J (Hz): 8.32 (doub. 4H, J ¼ 9.0, AreNO2), 8.20 (doub. 4H, J ¼ 9.0,
AreCO), 4.41 (trip. 4H, J ¼ 7.1, CH2O),1.91 (pent. 4H, J ¼ 6.9, CH2). 13
C
NMR (DMSO-d6) in
d (ppm): 164.75 (2C, C]O), 150.70 (2C, Ar C1),
135.62 (2C, Ar C4), 131.08 (4C, Ar C3,30), 124.34 (4C, Ar C2,20), 65.65
(2C, OCH2), 25.26 (2C, CH2).
2.4. Synthesis of diamine monomers
The organic diamine monomers of the general formula l,m-
bis(4-amino benzoyloxy)alkanes (m ¼ 2e6) were synthesized in
two steps (Scheme 2) from p-nitrobenzoyl chloride, which was
prepared according to the reported procedure [35]. The dinitro
precursors were prepared in the first step and reduced to the
diamine monomers in the second step as follows:
2.4.1.4. Preparation of 1,5-bis(4-nitrobenzoyloxy)pentane (N-5).
1,5-Bis(4-nitrobenzoyloxy)pentane (N-5) was prepared using 1,5-
pentane diol (1.41 ml; 13.47 mmol) by the aforementioned gen-
eral procedure. Yield 91%, m.p. 114 ꢂC. Elemental analysis for
C
19H18N2O8 (MW ¼ 402) in wt% calc. C ¼ 56.72, H ¼ 4.47, N ¼ 6.96
and found C ¼ 57.02, H ¼ 4.48, N ¼ 7.34. FTIR (KBr pellet) in cmꢁ1
:
3112, 3082 (w, CeH stretch Ar), 2969, 2854 (w, CeH stretch Al),
1722 (s, ester C]O stretch), 1606 (m, C]C stretch Ar), 1524, 1351 (s,
2.4.1. Synthesis of dinitro compounds (N-2, N-3, N-4, N-5 and N-6)
To a pre-baked three-neck round bottom glass flask equipped
with a magnetic stirrer, reflux condenser and nitrogen inlet, a ho-
mogeneous solution of the corresponding diol (13.47 mmol) and
triethyl amine (3.734 ml; 26.94 mmol) in anhydrous toluene
(50 ml) was introduced. The reaction mixture was cooled to 10 ꢂC
and p-nitrobenzoyl chloride (5 g; 26.94 mmol) dissolved in toluene
(15 ml) was added drop-wise over a period of 15 min. After com-
plete addition, the mixture was refluxed for 3 h under inert con-
ditions. The mixture was then allowed to cool and excess solvent
was evaporated under vacuum. The solid obtained was isolated by
filtration and stirred with distilled water for 1 h, again filtered and
recrystallized with ethanol to afford the pure dinitro compound.
NO2 stretch), 856 (m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d (ppm)
and J (Hz): 8.23 (doub. 4H, J ¼ 8.4, AreNO2), 8.13 (doub. 4H, J ¼ 8.4,
AreCO), 4.38 (trip. 4H, J ¼ 6.9, CH2O), 1.81 (pent. 4H, J ¼ 7.3, OCH2e
CH2eCH2), 1.19 (pent. 2H, J ¼ 7.4, CH2eCH2eCH2). 13C NMR (DMSO-
d6) in
d (ppm): 167.29 (2C, C]O), 149.47 (2C, Ar C1), 141.34 (2C, Ar
C4), 130.80 (4C, Ar C3,30), 123.70 (4C, Ar C2,20), 64.60 (2C, CH2O),
28.74 (2C, OCH2eCH2eCH2), 22.23 (1C, CH2eCH2eCH2).
2.4.1.5. Preparation of 1,6-bis(4-nitrobenzoyloxy)hexane (N-6).
1,6-Bis(4-nitrobenzoyloxy)hexane (N-6) was synthesized by the
general procedure using 1,6-hexane diol (1.58 g; 13.47 mmol). Yield
89%, m.p. 113 ꢂC. Elemental analysis for C20H20N2O8 (MW ¼ 416) in
wt % calc. C ¼ 57.69, H ¼ 4.80, N ¼ 6.73 and found C ¼ 57.85,
H ¼ 4.71, N ¼ 6.94. FTIR (KBr pellet) in cmꢁ1: 3117, 3081 (w, CeH
stretch Ar), 2933, 2859 (w, CeH stretch Al), 1726 (s, ester C]O
stretch), 1606 (m, C]C stretch Ar), 1526, 1349 (s, NO2 stretch), 859
2.4.1.1. Preparation of 1,2-bis(4-nitrobenzoyloxy)ethane (N-2).
The dinitro species 1,2-bis(4-nitrobenzoyloxy)ethane (N-2) was
prepared by the aforementioned general procedure using 1,2-
ethane diol (0.75 ml; 13.47 mmol). Yield 85%, m.p. 136 ꢂC.
Elemental analysis for C16H12N2O8 (MW ¼ 360) in wt% calc.
C ¼ 53.33, H ¼ 3.33, N ¼ 7.77 and found C ¼ 52.95, H ¼ 3.38,
N ¼ 7.92. FTIR (KBr pellet) in cmꢁ1: 3112, 3079 (w, CeH stretch Ar),
2958, 2856 (w, CeH stretch Al), 1720 (s, ester C]O stretch), 1608
(m, C]C stretch Ar), 1524, 1349 (s, NO2 stretch), 837 (m, p-C6H4
(m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d (ppm) and J (Hz): 8.32
(doub. 4H, J ¼ 8.7, AreNO2), 8.16 (doub. 4H, J ¼ 8.7, AreCO), 4.33
(trip. 4H, J ¼ 5.9, CH2O),1.76 (pent. 4H, J ¼ 7.1, OCH2eCH2eCH2),1.17
(pent. 4H, J ¼ 7.1, CH2eCH2eCH2). 13C NMR (DMSO-d6) in
d (ppm):
166.29 (2C, C]O), 150.64 (2C, Ar C1), 137.09 (2C, Ar C4), 131.16 (4C,
Ar C3,30), 124.39 (4C, Ar C2,20), 65.96 (2C, CH2O), 28.58 (2C, CH2e
CH2eCH2O), 25.79 (2C, CH2eCH2eCH2).
bend). 1H NMR (DMSO-d6) in
J ¼ 6.6, AreNO2), 8.29 (doub. 4H, J ¼ 6.8, AreCO), 4.77 (sing. 4H,
d (ppm) and J (Hz): 8.42 (doub. 4H,
CH2O). 13C NMR (DMSO-d6) in
d
(ppm): 164.46 (2C, C]O), 150.75
2.4.2. Synthesis of diamine monomers (D-2, D-3, D-4, D-5 and D-6)
A two-necked round bottom flask equipped with a magnetic
stirrer and reflux condenser was charged with a suspension of the
corresponding dinitro compound (12 mmol) and 10% Pd/C catalyst
(0.1 g) in ethanol (40 ml) and brought to reflux. A solution hydra-
zine hydrate (15 ml) in ethanol (30 ml) was then added drop-wise
over 30 min and the mixture was allowed to reflux for 10 h. The
mixture was filtered to remove PdeC and the filtrate was concen-
trated on a rotary vacuum evaporator to afford white solid pre-
cipitates which were washed thoroughly with distilled water and
recrystallized from ethanol to obtain the pure diamine product.
(2C, Ar C1), 134.94 (2C, Ar C4), 130.84 (4C, Ar C3,30), 123.66 (4C, Ar
C2,20), 63.36 (2C, OCH2).
2.4.1.2. Preparation of 1,3-bis(4-nitrobenzoyloxy)propane (N-3).
1,3-Bis(4-nitrobenzoyloxy)propane (N-3) was prepared by the
procedure described above using 1,3-propane diol (0.97 ml;
13.47 mmol). Yield 83%, m.p. 108 ꢂC. Elemental analysis for
C
17H14N2O8 (MW ¼ 374) in wt% calc. C ¼ 54.54, H ¼ 3.74, N ¼ 7.48
and found C ¼ 54.57, H ¼ 3.63, N ¼ 7.80. FTIR (KBr pellet) in cmꢁ1
:
3116, 3094 (w, CeH stretch Ar), 2962, 2870 (w, CeH stretch Al),
1725 (s, ester C]O stretch), 1606 (m, C]C stretch Ar), 1527, 1356 (s,
NO2 stretch), 838 (m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d
(ppm)
2.4.2.1. Preparation of 1,2-bis(4-aminobenzoyloxy)ethane (D-2).
1,2-Bis(4-aminobenzoyloxy)ethane (D-2) was prepared by the
aforementioned general procedure using 1,2-bis(4-nitrobenzoyloxy)
ethane (N-2) (4.32 g; 12 mmol). Yield 73%, m.p. 205 ꢂC. Elemental
analysis for C16H16N2O4 (MW ¼ 300) in wt% calc. C ¼ 64.00, H ¼ 5.33,
N ¼ 9.33 and found C ¼ 64.30, H ¼ 5.27, N ¼ 9.62. FTIR (KBr pellet) in
and J (Hz): 8.32 (doub. 4H, J ¼ 7.2, AreNO2), 8.14 (doub. 4H, J ¼ 7.2,
AreCO), 4.24 (trip. 4H, J ¼ 6.9, CH2O), 2.13 (pent. 2H, J ¼ 7.3, CH2).
13C NMR (DMSO-d6) in
d (ppm): 166.26 (2C, C]O), 150.48 (2C, Ar
C1), 136.83 (2C, Ar C4), 131.15 (4C, Ar C3,30), 124.19 (4C, Ar C2,20),
62.39 (2C, OCH2), 27.41 (1C, CH2).

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
315
cmꢁ1: 3431, 3351 (m, NH2 stretch), 3231, 3044 (w, CeH stretch Ar),
2963, 2913 (w, CeH stretch Al), 1688 (s, ester C]O stretch), 1598 (m,
C]C stretch Ar), 1515 (m, NeH bend), 841 (m, p-C6H4 bend). 1H NMR
2860 (w, CeH stretch Al),1685 (s, ester C]O stretch),1597 (m, C]C
stretch Ar), 1514 (m, NeH bend), 843 (m, p-C6H4 bend). 1H NMR
(DMSO-d6) in
d
(ppm) and J (Hz): 7.63 (doub. 4H, J ¼ 8.7, AreCO),
(DMSO-d6) in
d
(ppm) and J (Hz): 7.63 (doub. 4H, J ¼ 8.7, AreCO), 6.56
6.55 (doub. 4H, J ¼ 8.7, AreNH2), 5.95 (sing. 4H, NH2), 4.14 (trip. 4H,
(doub. 4H, J ¼ 8.7, AreNH2), 5.96 (sing. 4H, NH2), 4.682 (sing. 4H,
J ¼ 6.7, CH2O), 1.67 (pent. 4H, J ¼ 6.9, CH2eCH2eCH2O), 1.424 (pent.
CH2O). 13C NMR (DMSO-d6) in
d
(ppm): 166.53 (2C, C]O),152.90 (2C,
4H, J ¼ 6.9, CH2eCH2eCH2). 13C NMR (DMSO-d6) in
d (ppm): 167.27
Ar C1), 130.78 (4C, Ar C3,30), 118.31 (2C, Ar C4), 114.15 (4C, Ar C2,20),
63.91 (2C, CH2O).
(2C, C]O), 153.52 (2C, Ar C1), 131.57 (4C, Ar C3,30), 116.74 (2C, Ar
C4), 113.49 (4C, Ar C2,20), 64.36 (2C, CH2O), 28.36 (2C, CH2eCH2e
CH2O), 25.44 (2C, CH2eCH2eCH2).
2.4.2.2. Preparation of 1,3-bis(4-aminobenzoyloxy)propane (D-3).
1,3-Bis(4-aminobenzoyloxy)propane (D-3) was synthesized by the
general procedure described above by reducing 1,3-bis(4-
nitrobenzoyloxy)propane (N-3) (4.5 g; 12 mmol). Yield 76%, m.p.
125.2 ꢂC. Elemental analysis for C17H18N2O4 (MW ¼ 314) in wt%
calc. C ¼ 64.97, H ¼ 5.73, N ¼ 8.92 and found C ¼ 64.40, H ¼ 5.67,
N ¼ 9.10. FTIR (KBr pellet) in cmꢁ1: 3394, 3341 (m, NH2 stretch),
3239, 2977 (w, CeH stretch Ar), 2946, 2869 (w, CeH stretch Al),
1693 (s, ester C]O stretch), 1600 (m, C]C stretch Ar), 1515 (m, Ne
2.5. Synthesis of block copolymers
In a two-necked pre-baked round-bottom flask, the corre-
sponding diamine (1.84 mmol) was dissolved freshly dried hot THF
(15 ml) and treated with triethylamine (10 ml) under an inert at-
mosphere. The temperature was lowered to 0 ꢂC using an ice bath
and 1,10-ferrocenedicarbonyl chloride (0.600 g, 1.92 mmol) in dry
THF (10 ml) was added drop-wise with vigorous stirring over a
period of 30 min. The temperature was slowly raised to room
temperature and PDMS (2 g; 0.076 mmol) dissolved in dry THF
(10 ml) was added drop-wise to the mixture. The mixture was then
allowed to reflux for 72 h. After completion of the reaction, the
reaction mixture was cooled to ambient temperature and poured
into an excess of methanol. The precipitated product was then
collected by filtration and washed several times with methanol and
hot n-hexane. The resulting product was dried in vacuum for 24 h.
The organic analogues were synthesized by similar procedure using
terephthaloyl chloride and isophthaloyl chloride. Synthesis of these
copolymers is summarized in Scheme 3.
H bend), 839 (m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d (ppm) and J
(Hz): 7.64 (doub. 4H, J ¼ 9.0, AreCO), 6.53 (doub. 4H, J ¼ 9.0, Are
NH2), 5.957 (sing. 4H, NH2), 4.22 (trip. 4H, J ¼ 6.4, OCH2), 2.07 (pent.
2H, J ¼ 6.5, CH2). 13C NMR (DMSO-d6) in
d (ppm): 166.64 (2C, C]O),
153.11 (2C, Ar C1), 130.87 (4C, Ar C3,30), 118.20 (2C, Ar C4), 113.75
(4C, Ar C2,20), 64.66 (2C, OCH2), 25.27 (1C, CH2).
2.4.2.3. Preparation of 1,4-bis(4-aminobenzoyloxy)butane (D-4).
1,4-Bis(4-aminobenzoyloxy)butane (D-4) was prepared by reduc-
tion of 1,4-bis(4-nitrophenoxy)butane (N-4) (4.66 g; 12 mmol)
using the above mentioned procedure. Yield 79%, m.p. 195.2 ꢂC.
Elemental analysis for C18H20N2O4 (MW ¼ 328) in wt% calc.
C ¼ 65.85, H ¼ 6.09, N ¼ 8.53 and found C ¼ 65.35, H ¼ 6.17,
N ¼ 8.88. FTIR (KBr pellet) in cmꢁ1: 3463, 3367 (m, NH2 stretch),
3245, 3030 (w, CeH stretch Ar), 2961, 2918 (w, CeH stretch Al),
1677 (s, ester C]O stretch), 1602 (m, C]C stretch Ar), 1519 (m, Ne
2.5.1. FcBC-2
Brown sticky solid; yield 68%. FT-IR (KBr pellet) in
n
(cmꢁ1):
3293 (m, NeH stretch), 3089, 3027 (w, CeH stretch Ar), 2936, 2851
(w, CeH stretch Al), 1711 (s, ester C]O stretch), 1653 (s, amide-I),
1531 (s, amide-II), 1261 (s, SieCH3), 1099, 1014 (s, SieOeSi
H bend), 835 (m, p-C6H4 bend). 1H NMR (DMSO-d6) in
d (ppm) and J
(Hz): 7.63 (doub. 4H, J ¼ 8.7, AreCO), 6.58 (doub. 4H, J ¼ 8.7, Are
stretch), 839 (m, C6H4 bend), 497 (m, Fe-Cp). 1H NMR in
d (ppm):
NH2), 5.96 (sing. 4H, NH2), 4.20 (trip. 4H, J ¼ 6.6, CH2O), 1.78 (pent.
0.11 (sing. SiCH3), 5.09e4.54 (br. 8H, Cp), 7.48e6.54 (mult. 8H, Ar),
4.24 (sing. 4H, OCH2).
4H, J ¼ 6.5, CH2). 13C NMR (DMSO-d6) in
d
(ppm): 166.37 (2C, C]O),
152.82 (2C, Ar C1), 130.94 (4C, Ar C3,30), 117.31 (2C, Ar C4), 113.79
(4C, Ar C2,20), 64.57 (2C, OCH2), 25.36 (2C, CH2).
2.5.2. FcBC-3
Brown sticky solid; yield 66%. FT-IR (KBr pellet) in
n
(cmꢁ1):
2.4.2.4. Preparation of 1,5-bis(4-aminobenzoyloxy)pentane (D-5).
1,5-Bis(4-aminobenzoyloxy)pentane (D-5) was prepared by the
above mentioned procedure using 1,5-bis(4-nitrobenzoyloxy)
pentane (N-5) (4.82 g; 12 mmol). Yield 80%, m.p. 132 ꢂC. Elemental
analysis for C19H22N2O4 (MW ¼ 342) in wt% calc. C ¼ 64.00,
H ¼ 5.33, N ¼ 9.33 and found C ¼ 64.30, H ¼ 5.27, N ¼ 9.62. FTIR
(KBr pellet) in cmꢁ1: 3432, 3336 (m, NH2 stretch), 3214, 3070 (w,
CeH stretch Ar), 2965, 2928 (w, CeH stretch Al), 1694 (s, ester C]O
stretch), 1597 (m, C]C stretch Ar), 1515 (m, NeH bend), 843 (m, p-
3301 (m, NeH stretch), 3171, 3053 (w, CeH stretch Ar), 2937, 2823
(w, CeH stretch Al), 1713 (s, ester C]O stretch), 1654 (s, amide-I),
1537 (s, amide-II), 1262 (s, SieCH3), 1097, 1019 (s, SieOeSi
stretch), 831 (m, C6H4 bend), 500 (m, Fe-Cp). 1H NMR in
d (ppm)
and J (Hz): 0.14 (sing. SiCH3), 5.03e4.51 (br. 8H, Cp), 7.60e6.49
(mult. 8H, Ar), 4.21 (trip. 4H, J ¼ 7.4, OCH2), 1.98 (pent. 2H, J ¼ 7.5,
CH2).
2.5.3. FcBC-4
C6H4 bend). 1H NMR (DMSO-d6) in
d
(ppm) and J (Hz): 7.62 (doub.
Brown sticky solid; yield 65%. FT-IR (KBr pellet) in n
(cmꢁ1): 3314
4H, J ¼ 8.7, AreCO), 6.57 (doub. 4H, J ¼ 8.4, AreNH2), 5.94 (sing. 4H,
NH2), 4.17 (trip. 4H, J ¼ 7.1, CH2O), 1.71 (pent. 4H, J ¼ 7.0, OCH2e
CH2eCH2), 1.48 (pent. 2H, J ¼ 7.1, CH2eCH2eCH2). 13C NMR (DMSO-
(m, NeH stretch), 3133, 3051 (w, CeH stretch Ar), 2949, 2866 (w,
CeH stretch Al), 1709 (s, ester C]O stretch), 1653 (s, amide-I), 1539
(s, amide-II), 1260 (s, SieCH3), 1100, 1018 (s, SieOeSi stretch), 829
d6) in
d
(ppm): 166.36 (2C, C]O), 153.89 (2C, Ar C1), 131.49 (4C, Ar
(m, C6H4 bend), 495 (m, Fe-Cp). 1H NMR in
d (ppm) and J (Hz): 0.17
C3,30), 116. 84 (2C, Ar C4), 113.12 (4C, Ar C2,20), 63.81 (2C, OCH2),
28.52 (2C, OCH2eCH2eCH2), 22.69 (1C, CH2eCH2eCH2).
(sing. SiCH3), 5.11e4.47 (br. 8H, Cp), 7.46e6.41 (mult. 8H, Ar), 4.13
(trip. 4H, J ¼ 7.3, OCH2), 1.87 (pent. 4H, J ¼ 7.3, CH2).
2.4.2.5. Preparation of 1,6-bis(4-aminobenzoyloxy)hexane (D-6).
1,6-Bis(4-aminobenzoyloxy)hexane (D-6) was prepared by the
general procedure using 1,6-bis(4-nitrobenzoyloxy)hexane (N-6)
(5 g; 12 mmol). Yield 78%, m.p. 166 ꢂC. Elemental analysis for
2.5.4. FcBC-5
Dark brown sticky solid; yield 67%. FT-IR (KBr pellet) in n
(cmꢁ1):
3317 (m, NeH stretch), 3146, 3073 (w, CeH stretch Ar), 2957, 2861
(w, CeH stretch Al), 1711 (s, ester C]O stretch), 1651 (s, amide-I),
1531 (s, amide-II), 1262 (s, SieCH3), 1099, 1017 (s, SieOeSi
C
20H24N2O4 (MW ¼ 356) in wt% calc. C ¼ 67.42, H ¼ 6.74, N ¼ 7.86
and found C ¼ 66.83, H ¼ 6.49, N ¼ 8.03. FTIR (KBr pellet) in cmꢁ1
:
stretch), 836 (m, C6H4 bend), 497 (m, Fe-Cp). 1H NMR in
d
(ppm)
3426, 3338 (m, NH2 stretch), 3219, 3070 (w, CeH stretch Ar), 2942,
and J (Hz): 0.13 (sing. SiCH3), 5.04e4.49 (br. 8H, Cp), 7.45e6.43

316
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
(mult. 8H, Ar), 4.21 (trip. 4H, J ¼ 7.2, OCH2), 1.74e1.48 (mult. 6H,
2.5.12. IBC-3
Off-white sticky solid; yield 60%. FT-IR (KBr pellet) in
CH2).
n
(cmꢁ1):
3305 (m, NeH stretch), 3153, 3062 (w, CeH stretch Ar), 2969, 2856
(w, CeH stretch Al), 1709 (s, ester C]O stretch), 1655 (s, amide-I),
1529 (s, amide-II), 1262 (s, SieCH3), 1098, 1017 (s, SieOeSi
2.5.5. FcBC-6
Dark brown sticky solid; yield 68%. FT-IR (KBr pellet) in n
(cmꢁ1):
3299 (m, NeH stretch), 3139, 3049 (w, CeH stretch Ar), 2933, 2847
(w, CeH stretch Al), 1707 (s, ester C]O stretch), 1652 (s, amide-I),
1528 (s, amide-II), 1262 (s, SieCH3), 1100, 1021 (s, SieOeSi
stretch), 901, 764, 697 (m, C6H4 bend). 1H NMR in
d (ppm) and J
(Hz): 0.16 (sing. SiCH3), 7.52e6.46 (mult. 12H, Ar), 4.19 (trip. 4H,
J ¼ 6.9, OCH2), 1.88 (pent. 2H, J ¼ 6.8, CH2).
stretch), 829 (m, C6H4 bend), 503 (m, Fe-Cp). 1H NMR in
d (ppm)
and J (Hz): 0.15 (sing. SiCH3), 4.97e4.53 (br. 8H, Cp), 7.43e6.27
(mult. 8H, Ar), 4.17 (trip. 4H, J ¼ 7.3, OCH2), 1.64e1.49 (mult. 8H,
2.5.13. IBC-4
Off-white sticky solid; yield 59%. FT-IR (KBr pellet) in
n
(cmꢁ1):
CH2). LLS: Mw
¼
8.76
ꢃ
106
g
molꢁ1
;
hRgi
¼
31 nm;
3303 (m, NeH stretch), 3161, 3059 (w, CeH stretch Ar), 2939, 2878
(w, CeH stretch Al), 1711 (s, ester C]O stretch), 1652 (s, amide-I),
1529 (s, amide-II), 1262 (s, SieCH3), 1101, 1017 (s, SieOeSi
A2 ¼ 5.90 ꢃ 10ꢁ5 cm3 mol gꢁ2
.
2.5.6. TBC-2
stretch), 905, 797, 695 (m, C6H4 bend). 1H NMR in
d (ppm) and J
White sticky solid; yield 61%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3313
(Hz): 0.17 (sing. SiCH3), 7.49e6.33 (mult. 12H, Ar), 4.28 (trip. 4H,
J ¼ 7.0, OCH2), 1.81 (pent. 4H, J ¼ 7.3, CH2).
(m, NeH stretch), 3112, 3073 (w, CeH stretch Ar), 2937, 2880 (w, Ce
H stretch Al), 1706 (s, ester C]O stretch), 1647 (s, amide-I), 1529 (s,
amide-II), 1261 (s, SieCH3), 1097, 1017 (s, SieOeSi stretch), 831 (m,
2.5.14. IBC-5
C6H4 bend). 1H NMR in
d
(ppm): 0.09 (sing. SiCH3), 7.33e6.39 (mult.
Off-white sticky solid; yield 64%. FT-IR (KBr pellet) in n
(cmꢁ1):
12H, Ar), 4.23 (sing. 4H, OCH2).
3311 (m, NeH stretch), 3157, 3049 (w, CeH stretch Ar), 2966, 2835
(w, CeH stretch Al), 1707 (s, ester C]O stretch), 1652 (s, amide-I),
1531 (s, amide-II), 1260 (s, SieCH3), 1093, 1017 (s, SieOeSi
2.5.7. TBC-3
Off-white sticky solid; yield 64%. FT-IR (KBr pellet) in
n
(cmꢁ1):
stretch), 894, 799, 701 (m, C6H4 bend). 1H NMR in
d (ppm) and J
3317 (m, NeH stretch), 3139, 3064 (w, CeH stretch Ar), 2956, 2871
(w, CeH stretch Al), 1711 (s, ester C]O stretch), 1652 (s, amide-I),
1527 (s, amide-II), 1263 (s, SieCH3), 1107, 1023 (s, SieOeSi
(Hz): 0.17 (sing. SiCH3), 7.49e6.34 (mult. 12H, Ar), 4.27 (trip. 4H,
J ¼ 7.1, OCH2), 1.85e1.63 (mult. 6H, CH2).
stretch), 833 (m, C6H4 bend). 1H NMR in
d
(ppm) and J (Hz): 0.15
2.5.15. IBC-6
(sing. SiCH3), 7.42e6.59 (mult. 12H, Ar), 4.24 (trip. 4H, J ¼ 6.9,
Off-white sticky solid; yield 67%. FT-IR (KBr pellet) in n
(cmꢁ1):
OCH2), 1.93 (pent. 2H, J ¼ 7.0, CH2).
3309 (m, NeH stretch), 3167, 3059 (w, CeH stretch Ar), 2943, 2869
(w, CeH stretch Al), 1708 (s, ester C]O stretch), 1651 (s, amide-I),
1529 (s, amide-II), 1263 (s, SieCH3), 1097, 1016 (s, SieOeSi
2.5.8. TBC-4
Off-white sticky solid; yield 62%. FT-IR (KBr pellet) in
n
(cmꢁ1):
stretch), 889, 801, 706 (m, C6H4 bend). 1H NMR in
d (ppm) and J
3321 (m, NeH stretch), 3132, 3057 (w, CeH stretch Ar), 2946, 2869
(w, CeH stretch Al), 1709 (s, ester C]O stretch), 1650 (s, amide-I),
1522 (s, amide-II), 1261 (s, SieCH3), 1099, 1022 (s, SieOeSi
(Hz): 0.19 (sing. SiCH3), 7.51e6.36 (mult. 12H, Ar), 4.26 (trip. 4H,
J ¼ 6.9, OCH2), 1.93e1.57 (mult. 8H, CH2).
stretch), 829 (m, C6H4 bend). 1H NMR in
d
(ppm) and J (Hz): 0.14
2.6. Synthesis of polyesteramides
(sing. SiCH3), 7.44e6.31 (mult. 12H, Ar), 4.29 (trip. 4H, J ¼ 7.3,
OCH2), 1.92 (pent. 4H, J ¼ 7.3, CH2).
The corresponding polyesteramides of the synthesized block co-
polymers, without polydimethylsiloxane (PDMS) segment, were
prepared under similar conditions. In a two-necked pre-baked flask,
the corresponding diamine (1.84 mmol) was dissolved in freshly
dried hot THF (15 ml) and treated with triethylamine (10 ml) under
an inert atmosphere. The temperature was lowered to 0 ꢂC using an
ice bath and 1,10-ferrocenedicarbonyl chloride (0.600 g, 1.92 mmol)
dissolved in dry THF (10 ml) was added drop-wise with vigorous
stirring over a period of 30 min. The temperature was slowly raised to
room temperature and the mixture was stirred for 1 h and then
allowed to reflux for an additional hour. The precipitated product was
then collected by filtration, washed with THF (3 ꢃ 5 ml) and several
times with methanol. The resulting product was dried in vacuum for
24 h. The organic analogues of the polyesteramides were prepared by
similar procedure using terephthaloyl chloride and isophthaloyl
chloride. Synthesis of these polyamides is summarized in Scheme 4.
2.5.9. TBC-5
Pale sticky solid; yield 65%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3308
(m, NeH stretch), 3146, 3063 (w, CeH stretch Ar), 2915, 2866 (w,
CeH stretch Al), 1703 (s, ester C]O stretch), 1649 (s, amide-I), 1533
(s, amide-II), 1262 (s, SieCH3), 1098, 1014 (s, SieOeSi stretch), 834
(m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz): 0.16 (sing. SiCH3),
7.43e6.39 (mult. 12H, Ar), 4.23 (trip. 4H, J ¼ 7.1, OCH2), 1.89e1.53
(mult. 6H, CH2).
2.5.10. TBC-6
Pale sticky solid; yield 67%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3301
(m, NeH stretch), 3163, 3037 (w, CeH stretch Ar), 2933, 2874 (w,
CeH stretch Al), 1704 (s, ester C]O stretch), 1650 (s, amide-I), 1538
(s, amide-II), 1264 (s, SieCH3), 1107, 1022 (s, SieOeSi stretch), 833
(m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz): 0.19 (sing. SiCH3),
7.55e6.34 (mult. 12H, Ar), 4.24 (trip. 4H, J ¼ 7.3, OCH2), 1.94e1.66
2.6.1. FcA-2
(mult. 8H, CH2).
Reddish brownsolid; yield86%. FT-IR (KBrpellet)inn
(cmꢁ1):3316
(m, NeH stretch), 3098, 3032 (w, CeH stretch Ar), 2927, 2846(w, CeH
stretch Al), 1712 (s, ester C]O stretch), 1654 (s, amide-I), 1523 (s,
2.5.11. IBC-2
Off-white sticky solid; yield 61%. FT-IR (KBr pellet) in
n
(cmꢁ1):
amide-II), 823 (m, C6H4 bend), 490 (m, Fe-Cp). 1H NMR in
d (ppm):
3298 (m, NeH stretch), 3134, 3055 (w, CeH stretch Ar), 2963, 2858
(w, CeH stretch Al), 1713 (s, ester C]O stretch), 1653 (s, amide-I),
1532 (s, amide-II), 1259 (s, SieCH3), 1103, 1025 (s, SieOeSi
5.08e4.53 (br. 8H, Cp), 7.64e6.53 (mult. 8H, Ar), 4.18 (sing. 4H, OCH2).
2.6.2. FcA-3
stretch), 899, 786, 692 (m, C6H4 bend). 1H NMR in
d
(ppm): 0.15
Reddish brown solid; yield 88%. FT-IR (KBr pellet) in
3328 (m, NeH stretch), 3130, 3053 (w, CeH stretch Ar), 2944, 2821
n
(cmꢁ1):
(sing. SiCH3), 7.54e6.41 (mult. 12H, Ar), 4.23 (sing. 4H, OCH2).

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
317
COCH3
COCH3
COOH
COOH
COCl
COCl
SOCl2; Et3N
CH2Cl2; 2 h
CH3COCl; AlCl3
NaOCl
Fe
Fe
Fe
Fe
45-50oC; 5 h
CH2Cl2; 5 h
0-25oC
Scheme 1. Synthesis of ferrocene monomer (1,10-ferrocenedicarbonyl chloride).
(w, CeH stretch Al), 1709 (s, ester C]O stretch), 1653 (s, amide-I),
CeH stretch Al), 1708 (s, ester C]O stretch), 1651 (s, amide-I), 1518
1534 (s, amide-II), 828 (m, C6H4 bend), 493 (m, Fe-Cp). 1H NMR in
(s, amide-II), 826 (m, C6H4 bend), 497 (m, Fe-Cp). 1H NMR in
d
(ppm) and J (Hz): 5.03e4.46 (br. 8H, Cp), 7.61e6.53 (mult. 8H, Ar),
d (ppm) and J (Hz): 4.99e4.50 (br. 8H, Cp), 7.71e6.66 (mult. 8H, Ar),
4.11 (trip. 4H, J ¼ 7.2, OCH2), 2.01 (pent. 2H, J ¼ 7.3, CH2).
4.21 (trip. 4H, J ¼ 7.3, OCH2), 1.78e1.68 (mult. 8H, CH2).
2.6.3. FcA-4
2.6.6. TA-2
Brown solid; yield 90%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3317 (m,
White solid; yield 87%. FT-IR (KBr pellet) in n
(cmꢁ1): 3349 (m,
NeH stretch), 3123, 3042 (w, CeH stretch Ar), 2943, 2887 (w, CeH
stretch Al), 1707 (s, ester C]O stretch), 1654 (s, amide-I), 1519 (s,
NeH stretch), 3115, 3084 (w, CeH stretch Ar), 2931, 2877 (w, CeH
stretch Al), 1704 (s, ester C]O stretch), 1646 (s, amide-I), 1531 (s,
amide-II), 835 (m, C6H4 bend), 498 (m, Fe-Cp). 1H NMR in
d
(ppm)
amide-II), 837 (m, C6H4 bend). 1H NMR in
12H, Ar), 4.11 (sing. 4H, OCH2).
d (ppm): 7.74e6.62 (mult.
and J (Hz): 5.07e4.49 (br. 8H, Cp), 7.67e6.60 (mult. 8H, Ar), 4.19
(trip. 4H, J ¼ 6.9, OCH2), 1.97 (pent. 4H, J ¼ 7.7, CH2).
2.6.7. TA-3
2.6.4. FcA-5
White solid; yield 86%. FT-IR (KBr pellet) in n
(cmꢁ1): 3335 (m,
Dark brown solid; yield 91%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3339
NeH stretch), 3118, 3077 (w, CeH stretch Ar), 2922, 2852 (w, CeH
stretch Al), 1707 (s, ester C]O stretch), 1650 (s, amide-I), 1531 (s,
(m, NeH stretch), 3119, 3072 (w, CeH stretch Ar), 2923, 2852 (w, Ce
H stretch Al), 1711 (s, ester C]O stretch), 1651 (s, amide-I), 1529 (s,
amide-II), 803 (m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz): 7.68e
amide-II), 834 (m, C6H4 bend), 501 (m, Fe-Cp). 1H NMR in
d
(ppm)
6.42 (mult. 12H, Ar), 4.22 (trip. 4H, J ¼ 7.1, OCH2), 1.97 (pent. 2H,
and J (Hz): 5.03e4.51 (br. 8H, Cp), 7.69e6.54 (mult. 8H, Ar), 4.21
(trip. 4H, J ¼ 6.9, OCH2), 1.71e1.49 (mult. 6H, CH2).
J ¼ 7.0, CH2).
2.6.8. TA-4
2.6.5. FcA-6
Off-white solid; yield 89%. FT-IR (KBr pellet) in n
(cmꢁ1): 3321
Dark brown solid; yield 93%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3327
(m, NeH stretch), 3117, 3081 (w, CeH stretch Ar), 2931, 2847 (w, Ce
H stretch Al), 1702 (s, ester C]O stretch), 1649 (s, amide-I), 1527 (s,
(m, NeH stretch), 3124, 3047 (w, CeH stretch Ar), 2924, 2855 (w,
amide-II), 817 (m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz): 7.79e
6.56 (mult. 12H, Ar), 4.23 (trip. 4H, J ¼ 7.1, OCH2), 1.93 (pent. 4H,
J ¼ 7.5, CH2).
2.6.9. TA-5
Pale solid; yield 90%. FT-IR (KBr pellet) in n
(cmꢁ1): 3314 (m, Ne
H stretch), 3128, 3076 (w, CeH stretch Ar), 2937, 2858 (w, CeH
stretch Al), 1704 (s, ester C]O stretch), 1643 (s, amide-I), 1523 (s,
amide-II), 821 (m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz): 7.71e
6.56 (mult. 12H, Ar), 4.19 (trip. 4H, J ¼ 7.1, OCH2), 1.72e1.51 (mult.
6H, CH2).
2.6.10. TA-6
Off-white solid; yield 92%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3319
(m, NeH stretch), 3123, 3038 (w, CeH stretch Ar), 2929, 2856 (w,
CeH stretch Al), 1699 (s, ester C]O stretch), 1643 (s, amide-I), 1528
(s, amide-II), 827 (m, C6H4 bend). 1H NMR in
d (ppm) and J (Hz):
7.78e6.63 (mult. 12H, Ar), 4.26 (trip. 4H, J ¼ 7.3, OCH2), 1.73e1.49
(mult. 8H, CH2).
2.6.11. IA-2
White solid; yield 87%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3321 (m,
NeH stretch), 3121, 3049 (w, CeH stretch Ar), 2933, 2857 (w, CeH
stretch Al), 1714 (s, ester C]O stretch), 1654 (s, amide-I), 1519 (s,
amide-II), 884, 809, 723 (m, C6H4 bend). 1H NMR in
6.61 (mult. 12H, Ar), 4.22 (sing. 4H, OCH2).
d
(ppm): 7.56e
2.6.12. IA-3
Off-white solid; yield 86%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3329
(m, NeH stretch), 3113, 3044 (w, CeH stretch Ar), 2962, 2852 (w,
CeH stretch Al), 1712 (s, ester C]O stretch), 1652 (s, amide-I), 1531
(s, amide-II), 897, 765, 692 (m, C6H4 bend). 1H NMR in
d (ppm) and J
(Hz): 7.71e6.59 (mult. 12H, Ar), 4.19 (trip. 4H, J ¼ 6.9, OCH2), 1.98
Scheme 2. Synthesis of organic diamine monomers.
(pent. 2H, J ¼ 6.8, CH2).

318
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
2.6.13. IA-4
ester linkages were synthesized in two steps (Scheme 2). The
Off-white solid; yield 89%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3323
dinitro-diesters of the general formula 1,m-bis(4-nitrobenzoyloxy)
alkanes (m ¼ 2e6), were prepared in good yields in the first step by
nucleophilic substitution reactions under an inert atmosphere us-
ing SchotteneBaumann conditions [36]. The reaction occurred
immediately at low temperature (10 ꢂC) as precipitated Et3NeHCl
(derived from hydrochloric acid produced in the reaction and
triethyl amine) was observed as soon as the solution of 4-
nitrobenzoyl chloride in reaction solvent was added drop-wise to
the reaction flask. The low temperature conditions were required to
prevent the hydrolysis of the ester group (O]CeO). It was also
observed that the replacement of the toluene reaction solvent with
THF had no marked effect upon reaction times or yields of the final
products.
The synthesized dinitro precursors were then reduced in the
second step to the corresponding semi-aromatic diamine com-
pounds, 1,m-bis (4-aminobenzoyloxy)alkanes (m ¼ 2e6) using
hydrazine monohydrate as reducing agent. The solution of hydra-
zine hydrate in ethanol (1:2) was added drop-wise over half an
hour to the suspension of dinitro species and PdeC catalyst in
refluxing ethanol in order to avoid the hydrazinolysis of the ester
group during reduction. The reaction mixture was then evaporated
on a rotary vacuum evaporator to afford the diamine monomer,
which was washed thoroughly with distilled water to remove the
traces of hydrazine.
The synthesized dinitro precursors (N-2, N-3, N-4, N-5 and N-6)
and the diamine monomers (D-2, D-3, D-4, D-5 and D-6) were
purified by recrystallization in ethanol and their purity were
checked by TLC in n-hexane and ethyl acetate (1:1) mixture. The
dinitro-diesters were yellow while the diamine monomers were
white in colour. All these compounds were soluble in common
organic solvents (ethanol, chloroform, toluene, etc.) and possessed
sharp melting points. The observed values for carbon, hydrogen
and nitrogen of the intermediates and the resulting monomers
were in good agreement with the calculated ones.
(m, NeH stretch), 3119, 3047 (w, CeH stretch Ar), 2941, 2856 (w, Ce
H stretch Al), 1713 (s, ester C]O stretch), 1653 (s, amide-I), 1518 (s,
amide-II), 892, 779, 701 (m, C6H4 bend). 1H NMR in
d (ppm) and J
(Hz): 7.72e6.67 (mult. 12H, Ar), 4.23 (trip. 4H, J ¼ 7.3, OCH2), 1.99
(pent. 4H, J ¼ 7.1, CH2).
2.6.14. IA-5
Pale solid; yield 92%. FT-IR (KBr pellet) in n
(cmꢁ1): 3326 (m, Ne
H stretch), 3113, 3056 (w, CeH stretch Ar), 2937, 2856 (w, CeH
stretch Al), 1711 (s, ester C]O stretch), 1651 (s, amide-I), 1524 (s,
amide-II), 897, 778, 699 (m, C6H4 bend). 1H NMR in
d (ppm) and J
(Hz): 7.69e6.53 (mult. 12H, Ar), 4.24 (trip. 4H, J ¼ 6.9, OCH2), 1.67e
1.58 (mult. 6H, CH2).
2.6.15. IA-6
Off-white solid; yield 91%. FT-IR (KBr pellet) in
n
(cmꢁ1): 3325
(m, NeH stretch), 3116, 3064 (w, CeH stretch Ar), 2925, 2854 (w,
CeH stretch Al), 1713 (s, ester C]O stretch), 1651 (s, amide-I), 1527
(s, amide-II), 851, 766, 693 (m, C6H4 bend). 1H NMR in
d (ppm) and J
(Hz): 7.34e6.51 (mult. 12H, Ar), 4.18 (trip. 4H, J ¼ 7.2, OCH2), 1.69e
1.61 (mult. 8H, CH2).
Stretch ¼ stretching, bend ¼ bending, m ¼ medium, s ¼ sharp,
w ¼ weak, Al ¼ aliphatic, Ar ¼ aromatic, br. ¼ broad, sing. ¼ singlet,
doub. ¼ doublet, trip. ¼ triplet, pent. ¼ pentet, mult. ¼ multiplet.
3. Results and discussion
3.1. Monomer synthesis and characterization
The ferrocene-based monomer, 1,10-ferrocene dicarbonyl chlo-
ride was prepared from ferrocene in three steps by an improved
and efficient method (Scheme 1) [34]. The diamine monomers,
bis(ester-amine)s, with variable aliphatic character and pre-formed
Scheme 3. Synthesis of block copolymers of ferrocene-based polyesteramides and their organic analogues with polydimethylsiloxane (PDMS).

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
319
The FTIR spectra of all the dinitro precursors exhibited two
characteristic nitro group bands at 1527e1522 cmꢁ1 (asymmetrical
stretching) and 1356e1349 cmꢁ1 (symmetrical stretching)
respectively. The ester group was characterized by a sharp ab-
sorption band at 1726e1718 cmꢁ1. The aromatic and aliphatic
moieties in the compoundꢁs1were identified by the bands at 3117e
3110 cmꢁ1, 3094e3078 cm (aromatic CeH stretching) and 2969e
2933 cmꢁ1, 2870e2854 cmꢁ1 (aliphatic CeH stretching) in each
spectrum. After reduction, the disappearance of nitro bands indi-
cated a virtually complete conversion of dinitro functionality to
diamine. Moreover, the spectra of synthesized diamines also con-
The 13C NMR spectra of the dinitro intermediates and synthe-
sized diamines also exhibited the signals due to the presence of
aromatic and methylene carbons. The presence of the ester group in
each compound was evident from the characteristic farthest
downfield signals (ca. 166 ppm) attributable to the carbonyl carbon
of the ester group.
The different dinitro intermediates and the diamines vary in the
number of methylene spacers. The intensities of the bands associ-
ated with the aliphatic moieties in the FTIR spectra changed with
the change in number of methylene spacers [36,37]. Moreover, the
number and integration of aliphatic protons were different in the
1H NMR spectra of the different dinitro intermediates and the
diamine monomers. The difference in methylene spacers was also
exhibited in the 13C NMR spectra by different number of signals.
The representative FTIR, 1H NMR and 13C NMR spectra of the dinitro
precursors and related diamine monomers are presented as
Supplementary material.
tained
a typical NeH stretching absorption pair at 3465e
3394 cmꢁ1 and 3374e3336 cmꢁ1. The presence of a sharp band
(1694e1674 cmꢁ1) in each spectrum shows that the carbonyl ester
group is intact in the synthesized diamines. The shifting of bands to
lower wave numbers compared to those present in dinitro com-
pounds is due to the electron donating effect of NH2 group [36,37].
The spectra also contained the bands due to the aromatic and
aliphatic moieties.
3.2. Synthesis of block copolymers and their corresponding
polyesteramides
The 1H NMR spectra of the synthesized dinitro compounds were
also consistent with the proposed molecular structures. The signals
associated with different aromatic and aliphatic protons could be
observed in each spectrum. The aromatic protons in proximity to
NO2 groups resonated farthest downfield due to the deshielding
effect of the electron-withdrawing nitro groups [37]. The appear-
ance of characteristic signals at ca. 5.9 ppm corresponding to the
amino protons in the spectra of diamine monomers and the upfield
chemical shift of the aromatic protons due to the electron donating
ability of the amino group [36,37] confirmed the conversion of nitro
groups into the amino functionalities.
The block copolymers of structurally modified ferrocene-based
organometallic polyesteramides as well as their organic analogues
with aminopropyl-terminated polydimethylsiloxane (PDMS) olig-
omer were synthesized by a one-pot two-step solution poly-
condensation procedure in THF under inert conditions (Scheme 3).
The reaction did not proceed even after one week (168 h) reflux and
both reagents could be isolated when the polyesteramides were
synthesized separately and utilized for copolymerization with
PDMS, due to the conversion of terminal chloride functionalities
O
O
C
O
C
O
C
NH2
H2N
+
C O CH2
O
Cl
Ar
Cl
m
THF
Et3N
0oC to Room temp.
O
O
C
O
O
O
O
Cl
Ar
C
NH
C
Ar
C
Cl
HN
C O CH2
O
m
C
x
,
,
Ar
=
Fe
T
(Terephthaloyl)
I
Fc
(Ferrocenedicarbonyl)
(Isophthaloyl)
m=2-6
Scheme 4. Synthesis of corresponding organometallic and organic polyesteramides without polydimethylsiloxane (PDMS) segment.

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M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
into acid groups. Therefore, the polyesteramides were synthesized
in-situ and afterwards reacted with telechelic-PDMS in the same
pot in order to carry out the copolycondensation under strictly inert
conditions. The structures of the synthesized copolymers were
controlled by the molar ratios of the components. The stoichio-
metric ratio between the diamines and aminopropyl-terminated
PDMS oligomer (Mn w27,000) was maintained at 96:04 for all the
synthesized polymeric materials. The temperature of the reaction
was initially maintained at 0 ꢂC as the reaction is extremely
exothermic and the highly reactive diacyl chlorides may undergo
side reactions at higher temperatures distorting the molecular
stoichiometry which may inhibit the chain growth [38]. Telechelic-
PDMS was added at room temperature and the reaction mixture
was brought to reflux for 72 h as copolymerization reactions be-
tween incompatible segments usually require prolonged heating
[39]. THF was the solvent of choice for copolymerization as all the
reactants were soluble in it and it is usually used when polymers
with moderate molecular weights are required [40,41]. Triethyl
amine was used in excess to speed up the reaction by abstraction of
a proton from the acid (HCl) produced as a byproduct during the
reaction.
The corresponding polyesteramides of the synthesized block
copolymers were prepared under similar conditions without PDMS
oligomer (Scheme 4) in order to compare the structural features
and properties of the synthesized copolymers.
3.3. Structure elucidation of block copolymers and their
corresponding polyesteramides
The ferrocene-based block copolymers were brown sticky
solids, synthesized in fairly good yields and showed no change in
their colour and physical state up to 300 ꢂC. All the organic co-
polymers were also sticky solids, white or pale in colour, which did
not melt up to 300 ꢂC. The corresponding ferrocene-based poly-
esteramides, on the other hand, were brown solids whereas the
organic polyesteramides were white or off-white solids. The chain
structures of all the organometallic as well as organic copolymers
and their relevant polyesteramides were elucidated by their FT-IR
Fig. 1. FTIR spectra of copolymer FcBC-5 (a) and corresponding polyesteramide FcA-5 (b).

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
321
and 1H NMR spectroscopic studies and the molar masses were
determined by static laser light scattering technique.
attributed to SieOeSi asymmetric stretch, which confirmed the
incorporation of PDMS moiety in all these copolymers [26,39]. It is
reported that an isolated SieOeSi group gives a single broad band
near 1050 cmꢁ1 [26,39]. The precise position of this band depends
on the inductive, steric and mass effects of the substituents. The
disubstituted linear siloxane oligomers, on the other hand, exhibit
SieOeSi absorption for each unit in the chains, but these bands
overlap and develop a broad doublet pattern with absorption
maxima at 1090 and 1020 cmꢁ1, when the number of coupled
siloxane units becomes greater than 20 [26,39]. The distinguishing
feature of the spectra of ferrocene-containing organometallic co-
polymers was the presence of a medium intensity FeeCp stretching
band in the range 503e495 cmꢁ1, which was absent in the spectra
of the organic copolymers. It was observed that there exists a
remarkable similarity among the spectra of the organometallic and
organic copolymers except for the bands associated with aliphatic
The FT-IR spectra of the block copolymers provided evidence for
the presence of all expected functional groups in their backbone.
The spectra exhibited eNH stretching frequencies in the range
3321e3293 cmꢁ1, amide-I bands (associated with the stretching
vibration of the carbonyl group [42]) in the range 1654e1647 cmꢁ1
and amide-II absorption bands [42] (ascribed to the coupling of the
NeH bending and CeN stretching of the CeNeH group) in the
range 1539e1522 cmꢁ1 along with the bands attributed to the
presence of aromatic and aliphatic moieties. The presence of ester
group in the synthesized copolymers could also be identified in the
respective spectra by a sharp absorption band at 1713e1703 cmꢁ1
.
In addition, the spectra also exhibited prominent peaks at ca.
1262 cmꢁ1 due to symmetrical CH3eSi deformation modes and a
doublet with maxima at ca. 1107e1093 cmꢁ1 and 1025e1014 cmꢁ1
Fig. 2. 1H NMR spectra of the synthesized copolymer FcBC-4 (a) and corresponding polyesteramide FcA-4 (b).

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M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
Table 1
Static laser light-scattering results of the synthesized copolymersa in toluene at
25 ꢂC.
Polymer
Mw ꢃ 10ꢁ5 (g molꢁ1
)
hRgi (nm)
A2 (cm3 mol gꢁ2
)
FcBC-2
FcBC-3
FcBC-4
FcBC-5
FcBC-6
TBC-2
TBC-3
TBC-4
TBC-5
TBC-6
IBC-2
6.32
5.13
9.08
1.66
8.76
5.96
4.84
4.17
3.80
9.39
4.42
6.63
7.33
5.89
7.05
43
46
55
33
31
51
39
57
34
38
44
48
37
52
36
3.57 ꢃ 10ꢁ4
1.37 ꢃ 10ꢁ4
3.44 ꢃ 10ꢁ4
2.50 ꢃ 10ꢁ4
5.90 ꢃ 10ꢁ4
4.39 ꢃ 10ꢁ4
3.76 ꢃ 10ꢁ4
6.12 ꢃ 10ꢁ4
5.10 ꢃ 10ꢁ4
4.39 ꢃ 10ꢁ4
5.37 ꢃ 10ꢁ4
1.93 ꢃ 10ꢁ4
5.25 ꢃ 10ꢁ4
5.77 ꢃ 10ꢁ4
4.86 ꢃ 10ꢁ4
IBC-3
IBC-4
IBC-5
IBC-6
The relative errors are: dn/dC, ꢀ1%; Mw, ꢀ5%; hRgi and A2, ꢀ10%.
a
The data presented are for the N-trifluoroacetylated polymer species.
Fig. 3. Representative Zimm plot of the synthesized copolymer FcBC-5.
and aromatic CeH groups, which change essentially according to
the change in orientation (para or meta) and number of methylene
spacers. The FTIR spectrum of synthesized copolymer FcBC-5, as an
example, is shown in Fig. 1(a).
absorption frequency of the ordered amide-based polymers when
they are examined in the solid state [43,44]. The spectra of poly-
esteramides also exhibited very similar features with the exception
that the intensities of bands associated with aliphatic and aromatic
CeH groups were different due to changes in orientation (para or
meta) and number of methylene spacers as observed in the syn-
The FTIR spectra of the corresponding polyesteramides con-
tained strong absorption bands in the region 1714e1702 cmꢁ1 due
to the presence of ester groups [43] along with the amide-I and
amide-II bands. The eNH stretching frequency bands in these
polymers were present at ca. 3367e3314 cmꢁ1. The distinctive
feature of these bands was a shoulder in each spectrum in the range
3411e3376 cmꢁ1. The existence of the eNH bands with overlaying
shoulders indicates that more than one type of hydrogen bonding
with different bond distances for NeH group is present in these
polymers. This observation is in accord with the hydrogen-bonded
polyesteramides reported in the literature [43,44].
The ferrocene entities in the organometallic polyesteramides
could be ascertained by the presence of a medium intensity FeeCp
stretching band in the range 501e490 cmꢁ1, which was absent in
the spectra of the organic polyesteramides. The terephthaloyl-
based polyesteramides exhibited lower amide-I carbonyl absorp-
tion frequencies in their spectra (1650e1643 cmꢁ1) compared to
the isophthaloyl-based organic and ferrocene-containing organo-
metallic analogues (1654e1651 cmꢁ1). It is believed that hydrogen
bonding is the major factor contributing to the lower carbonyl
thesized copolymers.
A representative FTIR spectrum (poly-
esteramide FcA-5) is given in Fig. 1(b).
The chain structure of the synthesized copolymers was further
confirmed by their 1H NMR spectroscopic studies. The 1H NMR
spectra of the synthesized copolymers were recorded in THF-d8
after trifluoroacetylation without internal standard (tetramethly-
silane, TMS), which would interfere with SieCH3 signal. The spectra
displayed the most remarkable signal corresponding to PDMS
segment at ca. 0.0 ppm. All the signals attributed to the aromatic as
well as aliphatic protons present in the polyesteramide component
could also be identified in the spectra but their intensity was lower
relative to the sharp signal of SiCH3 protons indicating a smaller
mass ratio of hard polyesteramide components in the synthesized
copolymers compared to the soft PDMS segments. The comparison
of the peak area due to the silicon methyl protons with the peak
area resulting from the aromatic protons gave the relative
composition of the two blocks and suggested that the soft siloxane
component has been incorporated to slightly less than the calcu-
lated amount in all the synthesized copolymers. The presence of
the ferrocene moiety in the organometallic copolymers was
affirmed by the characteristic broad resonance signals in the region
5.11e4.47 ppm. This signal broadening indicates the presence of
paramagnetic impurities as a result of oxidation of ferrocene to
ferrocenium ion [45,46]. The signals attributed to the amide pro-
tons were absent in the spectra because of the fact that acetylation
Table 2
Static laser light-scattering results of the corresponding polyesteramidesa in toluene
at 25 ꢂC.
Polymer
Mw ꢃ 10ꢁ4 (g molꢁ1
)
hRgi (nm)
A2 (cm3 mol gꢁ2
)
FcA-2
FcA-3
FcA-4
FcA-5
FcA-6
TA-2
TA-3
TA-4
TA-5
TA-6
IA-2
3.92
4.17
4.68
4.94
6.73
3.86
4.02
5.12
5.58
3.39
4.42
4.64
6.21
5.19
6.55
30
33
29
24
38
25
28
21
32
23
22
27
34
33
31
5.87 ꢃ 10ꢁ4
2.14 ꢃ 10ꢁ4
8.34 ꢃ 10ꢁ3
1.62 ꢃ 10ꢁ4
7.27 ꢃ 10ꢁ4
5.15 ꢃ 10ꢁ4
4.76 ꢃ 10ꢁ4
6.93 ꢃ 10ꢁ4
4.28 ꢃ 10ꢁ4
8.13 ꢃ 10ꢁ3
3.64 ꢃ 10ꢁ4
2.77 ꢃ 10ꢁ4
9.33 ꢃ 10ꢁ3
3.42 ꢃ 10ꢁ4
2.31 ꢃ 10ꢁ4
Table 3
Water absorption studies of the representative copolymers and their respective
polyesteramides.a
Copolymer
Water absorption (%)
Polyesteramide
Water absorption (%)
FcBC-2
FcBC-6
TBC-2
TBC-6
IBC-2
0.96
0.99
0.94
0.98
0.89
0.87
FcA-2
FcA-6
TA-2
TA-6
IA-2
5.91
5.95
5.92
5.99
6.15
7.05
IA-3
IA-4
IA-5
IA-6
IBC-6
IA-6
The relative errors are: dn/dC, ꢀ1%; Mw, ꢀ5%; hRgi and A2, ꢀ10%.
a
a
The data presented are for the N-trifluoroacetylated polymer species.
Moisture absorption (%) ¼ ((Wf ꢁ Wo)/Wo) ꢃ 100.

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
323
occurs on the nitrogen of the amide bond and eliminates the amide
proton, which subsequently adds to the trifluorocarboxylate ion
yielding trifluoroacetic acid [47]. Therefore, a signal at ca. 11.5 ppm
was observed in the spectra.
The spectra of the related polyesteramides displayed all the
characteristic signals of the aromatic as well as aliphatic protons
anticipated for their constitution. The difference in the spectra of
the organometallic polymers compared to their organic analogues
was the presence of the characteristic chemical shifts of Cp protons
in the range 5.08e4.46 ppm. Exemplary 1H NMR spectra of the
synthesized copolymer (FcBC-4) and the corresponding poly-
esteramide (FcA-4) are presented in Figs. 2(a) and (b) respectively.
can be described by the Zimm formalism [48]. This allows the
determination of weight-average molar mass, radius of gyration
and shape information of the solute [49]. The molecular parameters
of the synthesized copolymers are given in Tables 1 and 2 and
representative Zimm plot (FcBC-5) is shown in Fig. 3. The weight-
average molar masses of the organometallic copolymers are in
the range 1.66 ꢃ 105 to 9.08 ꢃ 105 g molꢁ1, which is due to the
flexible high molar mass polydimethylsiloxane segment present in
the copolymer backbone and comparable with those reported for
the siloxane copolymers based on the polyamides containing tri-
chlorogermyl pendant groups [39]. The molar masses of the organic
analogues prepared under similar conditions also lie in the same
range (3.80 ꢃ 105 to 9.39 ꢃ 105 g molꢁ1), indicating that the method
used for the synthesis is equally suitable for ferrocene-based
organometallic copolymers as well as their organic analogues.
The high values also suggest that the synthesized materials are
multiblock copolymers [50]. In addition, the values for the radius of
gyration iRgh are also slightly high compared to the corresponding
organometallic polyesteramides, reflecting the long chain lengths
of these copolymers [39,51]. The positive values of the second virial
coefficient reflect a very strong polymeresolvent interaction [51]
3.4. Laser light-scattering results
The molecular parameters of the synthesized copolymers were
determined in toluene at 25 ꢂC by static laser light scattering (LLS)
after N-trifluoroacetylation. Static laser light scattering measures
light intensity as a function of scattering angle and solute concen-
tration, and the relationship between the light scattering from a
dilute polymer solution and the weight-average molecular weight
Fig. 4. Wide-angle X-ray diffractograms of some selected polymeric materials surface morphology.

324
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
indicating that N-trifluoroacetylation is an effective way to disrupt
the intermolecular interactions between the polymer chains which
allows the subsequent penetration of solvent molecules to these
structures.
The weight-average molar masses of the respective organome-
tallic polyesteramides and their organic analogues lie between
33,900 and 67,300 g molꢁ1. The radius of gyration hRgi values of
these polymers were in the range 21e38 nm and the second virial
coefficient values also indicated a very strong polymeresolvent
interaction upon trifluoroacetylation.
could be precipitated with methanol, water, etc. It is believed that
H2SO4 protonates the nitrogen of the amide group to overcome the
hydrogen bonding forces, thus solubilizing the polymers [52,54].
The corresponding organometallic as well as the organic poly-
esteramides also exhibited limited solubility in organic solvents
due to the rigid amide groups and hydrogen bonding in them
[52,53], and were found to be soluble in conc. H2SO4, as was the
case for their respective copolymers.
The synthesized copolymers and their polyesteramide counter-
parts could be solubilized in common organic solvents upon tri-
fluoroacetylation using trifluoroacetic anhydride (TFAA) as reported
in the literature [47,56]. Acetylation occurs on the nitrogen of the
amide bond and disrupts the hydrogen bonding to solubilize the
materials in the solvent medium [47]. All the synthesized organo-
metallic and organic copolymers could be trifluoroacetylated
readily and become solubilized when a few drops of TFAA are added
to the stirred suspension of the copolymer in the solvent (THF,
CHCl3, etc.) at 0 ꢂC. It was also observed that the ferrocene-based
organometallic polyamides and their isophthaloyl-based ana-
logues can be trifluoroacetylated easily and become soluble in the
common organic solvents upon 1e2 h stirring, compared to the
terephthaloyl-based polymers, which solubilize only after stirring
overnight (12 h). This behaviour may be attributed to the crystalline
nature of terephathaloyl-based polymers [57] in which the polymer
chains are highly ordered and densely packed rendering disruption
of inter-chain hydrogen bonding more difficult. The low solubility
of these polymeric and copolymeric materials suggests their
utilization in applications where extreme solvent resistance is
required.
3.5. Solubility behaviour
The solubility behaviour of the synthesized block copolymers
was tested qualitatively. All the polymeric materials were found
insoluble or slightly soluble in common organic solvents such as
chloroform, dichloromethane, etc. The insolubility may be attrib-
uted to the chain stiffness caused by the inherent rigidity of the
amide linkage present in the copolymers as well as the intermo-
lecular dipoleedipole and hydrogen bonding interactions between
the chains [52,53], and in part to the increase in molecular weights
on incorporation of the polydimethylsiloxane unit in the polymers
as the solubility decreases with the increase in molecular weight
[54]. The introduction of flexible methylene spacers along with
ester linkages which are generally recognized to enhance solubility
[8] did not prove greatly effective in breaking the intermolecular
interactions in the synthesized copolymers. It has been reported
that sometimes these flexible linkages play only a minor role in
solubility, their influence being subordinate to other groups in the
polymer chain [55]. The synthesized copolymers, however, were
partially soluble in polar aprotic solvents such as DMF and DMSO.
The limited solubility in polar aprotic solvents reveals the partial
ability of these solvents to overcome the intermolecular in-
teractions. The solubility was also tested in mixtures of solvents.
The solvent system containing toluene and THF (1:1) was effective
on heating to solubilize the synthesized copolymers but the solu-
bility decreased on cooling to room temperature. All the synthe-
sized copolymers were found to be soluble in conc. H2SO4 and
3.6. Water absorption studies
The water absorption studies of some representative co-
polymers and their respective polyesteramides were carried out
following the ASTM D570-81 procedure [31]. The results obtained
for these studies are listed in Table 3. The results show that all the
synthesized copolymers absorbed very little water (ca. 1%), in
contrast to their polyesteramide counterparts which absorbed
Fig. 5. Representative scanning electron micrographs of the synthesized block copolymers and their respective polyesteramide.

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
325
Fig. 6. Representative AFM topographic images and roughness profile graphs of the synthesized block copolymers and their corresponding polyesteramide.
water in the range 5.95e7.05%. The water absorption of poly-
esteramides is attributed to the abundance of polar ester and amide
groups exposed on the polymer surface where water molecules
develop secondary interactions with these groups [58], and can
adversely affect their mechanical and dielectric properties [58,59].
However, the hydrophilic nature makes the polyesteramides good
candidates for semi-permeable membranes, which can be
employed in the filtration of aqueous solutions and for water pu-
rification [55]. The low water absorption of the block copolymers,
on the other hand, is attributed to the tremendous hydrophobicity
and low surface tension of the siloxanes, due to which the siloxanes
come to the airepolymer interface [60] and thus the exposure of
polar groups to the polymer surface becomes remarkably low. Such
type of copolymers having hydrophobic together with hydrophilic
segments can be used in several applications such as the stabili-
zation of emulsions and dispersions of different substances and
have the ability to replace low-molecular weight materials in the
modification of different surfaces, foaming lubrication and formu-
lation of cosmetics [60].
The isophthaloyl-based organic polyesteramides generally
absorb more water compared to their other organic and organo-
metallic counterparts and polyesteramide IA-6 has the highest
water uptake value (7.05%) among these polymers probably due to
its amorphous nature and presence of more methylene spacers in
its backbone compared to other isophthaloyl-based polymers
consistent with previously reported observations [61]. It has been
reported that polymers containing moieties that aid in rigid close
packing exhibit lower water absorption compared to polymers
without such groups [62].
3.7. XRD analysis
Morphological information on the organometallic copolymers
and their organic analogues was obtained from their wide-angle X-
ray powder diffraction pattern in the region 2
q
¼ 0e70ꢂ at room
temperature and the representative X-ray diffractograms of the
polymeric materials are shown in Fig. 4. The broad peak patterns of
all the synthesized copolymers exhibited that they are amorphous
in nature. This may be attributed to the presence of siloxane moiety
in the backbone which diminishes the crystallinity [63]. The
respective polyesteramides, on the other hand, exhibited variable
crystallinity which can be correlated with their structural features.
The sharp peak patterns in diffractograms of the terephthaloyl-
based polyesteramides in the range 10e40ꢂ indicated that these
are of considerable crystallinity. This indicates that the polymeric
chains in the paraepara system are symmetric and ordered leading
to a more favourable conformation for packing [64]. All the
ferrocene-based organometallic polyamides are amorphous in na-
ture as revealed by the diffuse pattern in their diffractograms. This
indicates that the introduction of bulky ferrocene moieties in the
polyamides decreases the chainechain interactions, interrupting
the close packing of polymer chains and thereby decreasing the
crystallinity [65]. The isophthaloyl-based organic polymers were
also amorphous in nature as revealed by the typical amorphous
hollow pattern in their diffractograms, which shows that the
introduction of meta orientation into the polymer chains leads to
the distortion of the polymer lattice [57,66]. The X-ray diffraction
analysis also reveals that the crystallinity increases with the in-
crease in number of aliphatic spacers in the polymer chain as was
evident from the diffractogram of polymer TA-6, which has more
reflection peaks compared to that of polymer TA-4. This is
explained by the fact that increasing the number of methylene
groups in the polymer chain increases the flexibility as well as chain
regularity and hence increases the crystallinity [67].
Table 4
RMS roughness of the representative copolymers and their respective
polyesteramides.
Copolymer
RMS roughness (nm)
Polyesteramide
RMS roughness (nm)
FcBC-5
FcBC-6
TBC-5
TBC-6
IBC-5
234.58
224.64
227.16
244.39
239.50
241.25
FcA-5
FcA-6
TA-5
TA-6
IA-5
1.40
1.98
1.65
2.52
2.15
2.43
3.8. Surface morphology
The surface of the synthesized block copolymers was examined
by scanning electron microscopy (SEM) and atomic force micro-
scopy (AFM), which are complementary techniques used side-by-
IBC-6
IA-6

326
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
Fig. 7. EDX spectra of representative block copolymers and their corresponding polyesteramide.
side for surface investigations in modern laboratories [68]. The
scanning electron micrographs of the block copolymers revealed
that most of the surface of the synthesized copolymers was covered
by the siloxane segment and microphase separation can hardly be
detected. It has been reported that in siloxane-based copolymers
with higher siloxane content, the siloxane domains become a
dominant part of polymer surface [69]. The micrographs of the
selected samples (FcBC-6 and TBC-6) are presented in Figs. 5(a) and
(b). The AFM images of the copolymers, Fig. 6(a), also support the
argument and the copolymers exhibited high values of surface
roughness (Table 2) due to the migration of siloxane moiety to-
wards the airepolymer interface. This unique feature justifies the
use of siloxane-based materials as surface modifiers [70].
The SEM study of the ferrocene-based organometallic poly-
esteramides revealed that their surface consisted of granular par-
ticles while that of the organic polymers consisted of spherical
particles. The representative micrographs are depicted in Figs. 5(c)
and (d). The AFM images of the synthesized polyesteramides
exhibited an almost featureless morphology showing that these
polyamides possess smooth surfaces with little roughness (Table 4).
Table 5
DSC results of the synthesized copolymers and their corresponding polyesteramides.
Copolymer
Tg (ꢂC) (soft segment)
ꢁ118
Tm (ꢂC) (soft segment)
Tg (ꢂC) (hard segment)
Polyesteramide
Tg (ꢂC)
FcBC-2
FcBC-3
FcBC-4
FcBC-5
FcBC-6
TBC-2
TBC-3
TBC-4
TBC-5
TBC-6
IBC-2
ꢁ51.50
ꢁ55.40
ꢁ52.85
ꢁ52.30
ꢁ50.25
ꢁ49.50
ꢁ50.85
ꢁ51.75
ꢁ54.15
ꢁ49.55
ꢁ51.75
ꢁ54.20
ꢁ49.55
ꢁ51.75
ꢁ54.20
260
262
250
248
255
262
258
257
255
249
253
247
247
244
241
FcA-2
FcA-3
FcA-4
FcA-5
FcA-6
TA-2
TA-3
TA-4
TA-5
TA-6
IA-2
282
279
271
267
264
273
270
261
257
251
270
271
259
253
248
ꢁ123
a
ꢁ120
a
ꢁ122
a
ꢁ118
a
ꢁ119
ꢁ124
ꢁ120
ꢁ119
ꢁ124
ꢁ120
IBC-3
IBC-4
IBC-5
IBC-6
IA-3
IA-4
IA-5
IA-6
Tg ¼ glass transition temperature, Tm ¼ melting temperature.
a
Tg not detected.

M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
327
Fig. 8. DSC curves of the synthesized copolymer FcBC-6 (a) and respective polyesteramide FcA-6 (b).
The representative image is given in Fig. 6(b). The EDX patterns of
the synthesized organometallic polymers and copolymers also
provided evidence for the presence of iron metal in their structure
(Fig. 7). The EDX patterns of all the synthesized copolymers
confirmed the presence of silicon as well.
of the aliphatic methylene spacers and the orientation of the phe-
nylene rings. Fig. 9 shows that the glass transition temperatures of
the polyesteramides exhibit an essentially linear decrease with
increasing methylene chain length. The trend is in line with ob-
servations made by earlier workers for polymers containing flexible
methylene moieties [16]. The shifting of glass transition tempera-
ture values of the respective polyesteramides from those exhibited
by the synthesized copolymers indicates the variation in macro-
molecular chain packing in the block copolymers compared to the
homopolymers [71,72].
3.9. DSC studies
The differential scanning calorimetry (DSC) studies of the syn-
thesized copolymers were carried out at
a heating rate of
10 ꢂC minꢁ1 in nitrogen. The results obtained for these studies are
presented in Table 5. A unique feature of the block copolymers is
the microphase separation which is evident from the DSC profiles
of the synthesized copolymers (Fig. 8(a)) as both the segments
exhibit their representative thermal transitions in the DSC experi-
ments [26,39]. The soft PDMS segment showed a sharp peak at
ca. ꢁ50 ꢂC in all the spectra which is attributed to its melting
[26,39]. It also exhibited a glass transition temperature (Tg) at
ca. ꢁ120 ꢂC [71], which could be detected in most of the spectra.
The glass transition temperature (Tg) and melting temperature (Tm)
of a polymer are a reflection of the macromolecular chain motion
and the amount of free volume in the polymer [72]. The glass
transition temperatures of the hard polyesteramide segments are
high (241e262 ꢂC) and could also be observed in the spectra of the
synthesized copolymers.
4. Conclusions
A one-pot two-step solution polycondensation procedure was
employed for the synthesis of novel ferrocene-containing siloxane-
based block copolymers and their organic analogues. The corre-
sponding polyesteramides of the synthesized block copolymers,
without polydimethylsiloxane segment, were also prepared under
similar conditions for comparison of properties. All the organo-
metallic and organic block copolymers along with their respective
polyesteramides did not melt up to 300 ꢂC and were characterized
by their physical properties, FTIR and 1H NMR spectroscopic tech-
niques, which confirmed the presence all the expected moieties in
their macrochain. The synthesized copolymers and polyesteramide
materials were soluble in a tolueneeTHF (1:1) solvent mixture at
elevated temperatures and conc. H2SO4 at room temperature
and possessed low solubility in common organic solvents at
room temperature, yet became readily soluble upon N-tri-
fluoroacetylation with trifluoroacetic anhydride. The weight-
average molar masses for the synthesized organometallic block
copolymers were comparable with those of the organic analogues
and were significantly high compared to their respective poly-
esteramides suggesting that the synthesized block copolymers
consisted of multiblocks of hard and soft segments. These block
copolymers absorbed very small amounts (ca. 1%) of water
compared to their corresponding polyesteramides due to the hy-
drophobic siloxane moiety and can be used as semi-permeable
membranes. Wide-angle XRD studies revealed that all the organ-
ometallic and organic copolymers were amorphous in nature,
whereas the relevant polyesteramides were of variable crystallinity
depending upon their structural features. The surfaces of all the
synthesized copolymers exhibited diffused morphology due to
the migration of siloxane segment to the surface. The ferrocene-
based polyesteramides, on the other hand, exhibited granular
morphology while the organic polymers showed spherical surface
morphology. The DSC profiles of the synthesized ferrocene-based
The chain stiffness of the synthesized polyesteramides was
characterized by their glass transition temperatures (Tg) obtained
from the DSC curves (Fig. 8(b)). The glass transition temperatures of
the synthesized polymers were in the range 248e282 ꢂC in accor-
dance with the reported values of aromatic polyesteramides [73].
The variations in the Tg values could be correlated with the length
Ferrocene based
Terephthaloyl based
Isophthaloyl based
282
276
270
264
258
252
246
copolymers and their organic analogues exhibited
a phase-
2
3
4
5
6
separated morphology with two glass transition temperatures
(Tg) due to hard polyesteramide and soft polydimethylsiloxane
segments. The glass transition temperatures of the ferrocene-based
polyesteramides were higher than the organic analogues and
No. of Carbon atoms in aliphatic chain
Fig. 9. Plot of Tg vs. no. of carbon atoms in aliphatic chain of the synthesized
polyesteramides.

328
M. Saif Ullah Khan et al. / Journal of Organometallic Chemistry 745-746 (2013) 312e328
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aliphatic chain. In conclusion, these studies suggested that the
ferrocene-containing siloxane-based organometallic copolymers
and their organic analogues generally possessed superior proper-
ties and can be utilized in modification of surfaces and in applica-
tions where severe conditions requiring high solvent resistance and
elevated temperature environments are encountered.
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Acknowledgements
The authors would like to thank University Research Fund,
Quaid-i-Azam University, Islamabad, for the financial support of
this project.
Appendix A. Supplementary material
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