Dendronized rigid-flexible macromolecular architectures: Syntheses, structure, and properties in bulk

Article abstract of DOI:10.1021/ma035688p

Side-chain dendronized polymers consisting of regularly segmented alternating rigid-flexible main-chain units and side dendritic wedges are synthesized and analyzed in their bulk state using various experimental methods. High molecular weight polymers wer

Full text of DOI:10.1021/ma035688p

3576
Macromolecules 2004, 37, 3576-3587
Dendronized Rigid-Flexible Macromolecular Architectures: Syntheses,
Structure, and Properties in Bulk
A. K. An d r eop ou lou ,† B. Ca r bon n ier ,‡ J . K. Ka llitsis,*,† a n d T. P a k u la *,‡
Department of Chemistry, University of Patras, GR-265 00 Patras, Greece, and Foundation for
Research and Technology-Hellas, Institute of Chemical Engineering and High-Temperature Chemical
Processes, P. O. Box 1414, GR-265 00 Patras, Greece, and Max-Planck-Institute for Polymer Research,
Postfach 3148, 55021 Mainz, Germany
Received November 10, 2003; Revised Manuscript Received March 1, 2004
ABSTRACT: Side-chain dendronized polymers consisting of regularly segmented alternating rigid-flexible
main-chain units and side dendritic wedges are synthesized and analyzed in their bulk state using various
experimental methods. High molecular weight polymers were obtained in most cases enabling the
formation of self-supporting films. The thermal and mechanical characterization of these polymers, by
means of DSC and dynamic mechanical analyses, has revealed a highly ordered nature, which was further
supported from SALS and POM experiments. Additionally, their transition temperatures seem to strongly
depend on the main-chain flexible spacer’s length, in a manner resembling the odd-even effect. The
existence of organizational features in both isotropic and macroscopically oriented samples was concluded
for these polymeric materials due to the intense and well-resolved diffractions in their WAXS patterns.
From qualitative analyses of the WAXS patterns corresponding to oriented filaments, the development
of layered structures is postulated, comprised of main-chain polymeric backbones while the side dendrons
occupy the space between the layers. Actually, two types of LC ordering for the extended backbones within
the main-chain layers could be distinguished. In general, the exact polymeric structure, side-dendrons’
generation and main-chain flexible spacers’ length, greatly influence the final polymeric properties, such
as phase transitions and structural parameters.
In tr od u ction
that show good compatibility with one or the other
main-chain subunit could lead to even more complex
architectures where the molecules tend to organize on
the basis of the miscibility of the different segments.8
The development of well-defined molecular and supra-
molecular architectures still attracts increasing scien-
tific interest. Numerous pathways have so far been
adopted trying to mimic nature’s wiseness toward
complicated, self-assembled, and self-organized materi-
als.1 Dendrimers, dendrons, and side-chain dendritic
polymers offer unique opportunities for the development
of such novel and complex macromolecular entities due
to their evolutionary spherical or cylindrical shapes,
great number of building blocks, and the possibility of
several different functionalities coexisting in close prox-
imity.2,3 The delicate organization of many such macro-
molecules in larger self-assembled, self-organized sys-
tems is an intriguing aspect in dendrimer chemistry and
physics. The specific molecular architecture and inter-
molecular interactions can control the microphase sepa-
ration, aggregation phenomena, and order-disorder
situations that are essential for the arrangement of
these giant macromolecular species to a supramolecular
structure.4-7
Inserting different, incompatible moieties into a mac-
romolecular chain while at the same time allowing
mobility into the system for ordered conformations
finally to be adopted is a well-known “trick” for fabricat-
ing macroscopically organized materials.8 In particular,
rigid-flexible combinations may give rise to separation
tendencies into a system due to the incompatibility of
the segmental units. Such rod-coil molecules have so
far been well investigated although precise macro-
molecular rigid-flexible alternating systems are still
rare. Moreover, the introduction of side-chain moieties
This work focuses on a novel combination of the above
perspectives, in which side-chain dendritic polymers
consisting of rigid-flexible main-chain units and side
dendritic wedges were investigated. These dendronized
polyethers, prepared by the convergent “macro-
monomer” approach,3,9 bear terphenyl main-chain units,
carrying two side dendrons in their middle phenylene
ring, connected through aliphatic spacers of various
lengths. Thus, these polymeric series offer the possibility
of creating LC phases, since they contain the mesogenic
terphenyl units distributed along the main polymeric
backbones in a regular motive through the interfering
aliphatic segments. It is these aliphatic segments that
should provide flexibility into the system allowing for
favorable conformations to be adopted by the macro-
molecular chains depending on space requirements
imposed from the accommodation of such large side
dendritic substituents. Moreover, the selected dendrons
bear lengthy alkoxy chains at their periphery, resem-
bling those of the Percec type,5,6,10,11 in an effort to
increase segregation and organization phenomena oc-
curring due to the terphenyl and the aliphatic segments
of the main chain and due to the alkoxy periphery
groups and the phenylene branching points within the
dendrons themselves. Actually, a variety of alkoxy
periphery functionalized dendrons and dendrimers11 as
well as dendronized polymers12-15 have been reported
in the literature. Investigation of such polymeric sys-
tems has been performed mostly concerning their con-
formational behavior,16 polymerization kinetics,5,12 and
optical properties.14-17 Most interestingly, a pattern
seems to dominate the polymers’ organization: a pro-
† University of Patras.
‡ Max-Planck-Institute for Polymer Research.
* Corresponding authors.
10.1021/ma035688p CCC: $27.50 © 2004 American Chemical Society
Published on Web 04/10/2004

Macromolecules, Vol. 37, No. 10, 2004
Dendronized Macromolecular Architectures 3577
Sch em e 1. (i) K2CO3, Aceton e, Reflu x for 12 h , 80% (G1), or 24 h , 70% (G2); (ii) for 2(G1) P d (P P h )3, Tolu en e, Na 2CO3
2 M, r eflu x for 24 h , 90%; (iii) for 2(G2) P d Cl2(d p p f), THF , Na OH 3 M, Reflu x for 48 h , 70%; (iv) CSA, THF , MeOH,
18 h , 75% (G1), 60% (G2)
Sch em e 2 (i) o-DCB, Na OH 10 N, TBAH, 120 °C, 2-4 d a ys (G1), 4-8 d a ys (G2)
nounced tendency toward ordered structures with the
dendrons self-packing, thus forcing the polymeric back-
bones to adopt specific arrangements.
properties and structures developed has been thor-
oughly investigated.
Exp er im en ta l Section
In an effort to evaluate and understand our den-
dronized polymers and at the same time to discriminate
differentiations from other already reported ones, vari-
ous experimental techniques have been combined aim-
ing especially at their bulk properties’ characterization.
Consequently, the effect of the main-chain flexible
spacers’ length and of the dendrons’ generation on
Ma ter ia ls. Dendrons G1 and G2,10 1,4-dihydroxy-2,5-dibro-
mobenzene (1),18 and catalysts Pd(PPh3)4 and PdCl2(dppf)20
19
were prepared according to literature procedures. The syn-
thesis of 2-tetrahydropyranyloxy-4-phenylboronic acid (3) was
described in a previous publication.21 Tetrahydrofuran (THF)
was distilled from sodium prior to use. Solvents of analytical

3578 Andreopoulou et al.
Macromolecules, Vol. 37, No. 10, 2004
Ta ble 1. Molecu la r Ch a r a cter istics for th e Syn th esized
P olyeth er sa
Ta ble 2. Th er m a l An a lyses of P olyeth er s
P ETH-4OC12H25-xa
b
b
b
x
Mn
Mw
Mw/Mn
Mru
DPc
Second Heating
P ETH-4OC12H25-x
x
Tm
Tc
12d
11d
10e
9d
45 700
61 400
50 300
60 200
27 490
103 140
151 290
146 830
126 360
85 450
2.3
2.5
2.9
2.1
3.1
1376
1362
1348
1334
1320
33.2
45.1
37.3
45.1
20.8
12
84.8 (91)
{7.2/28.7}
98 (103.0)
{42.9}
95 (100.1)
{30.6}
98.2 (102.5)
{38.1}
104.3 (109.3)
{47.5}
49.7
{20.8}
56.2
{44.4}
57
{36.2}
65.8
{40.3}
73.5
{47.6}
11
10
9
8f
P ETH-8OC12H25-x
12g
11h
10e
32 240
16 950
11 970
90 850
40 250
25 650
2.8
2.4
2.2
2536
2522
2508
12.7
6.7
4.8
8
a
See Experimental Section for detailed synthetic procedures.
b
First Heatingb
From GPC with
a UV detector, CHCl3 as eluent, and PS
standards. c Number-average degree of polymerization calculated
by dividing Mn values with the theoretical molecular weights of
x
Tm
Tm
Tc
a
d
the monomer units (Mru) of the corresponding polyether. Poly-
12
11
10
45.7
51
49.9
78.2
87.5/94.8
93.9
{28.6}
97.3
{26.0}
104
43
52
53.7
merization at 120 °C, 3 days. e Polymerization at 120 °C, 4 days.
f Polymerization at 120 °C, 2 days. Polymerization at 120 °C, 8
g
h
days. Polymerization at 120 °C, 5 days.
9
8
50.4
49.9
60.7
68.3
grade purity were purchased from Aldrich or Merck and were
used without further purification unless otherwise noted. The
reagents 18-crown-6 (for synthesis), tetrabutylammonium
hydrogen sulfate (TBAH) (97+%, T), (1R)-(-)-10-camphoro-
sulfonic acid (CSA) (98%), K2CO3-NaOH-Na2CO3 (pro analy-
ses), and aliphatic dibromides [x ) 11 (98+%), x ) 9 (97%), x
) 8 (98%)] were supplied from Aldrich and used as received.
Aliphatic dibromides x ) 12 and x ) 10 were recrystallized
from methanol. All reactions were performed under an argon
atmosphere. Degassing of reaction mixtures was performed
by subsequent evacuations and filling with argon, cycles for
three times.
{30.1}
a
Tm , Tm, Tc ) at the peak maximum. Tm and Tm from the
a
a
heating run. Tc from the cooling run. (T) ) from the tangent at
b
the Tm peak. {∆H} ) kJ /mru. After aging of the samples for 3
months at room temperature.
with a 2 °C/min cooling rate and above 50 °C with a 2 °C/min
heating rate.
Polarized optical microscopy (POM) observations were
performed using a Zeiss microscope (D-7082) equipped with a
temperature-controlled stage (Linkam TMS91/THM600) and
a color digital camera (Hitachi KPD50). Small-angle light
scattering (SALS) experiments were conducted with a He-
Ne laser (λ ) 633 nm) beam and a CCD camera (Hamamatsu)
recording the 2D scattering patterns under Hv polarization
conditions. To determine spherulite sizes, the scattered inten-
sity distributions vs scattering angle were analyzed.22
1,4-Di[3,5-bis(d od ecyloxy)ben zyloxy]-2,5-d ibr om oben -
zen e (2(4OC12H25)). A mixture of 1 (1.00 g, 3.73 mmol),
dendron G1 (4.42 g, 8.20 mmol), K2CO3 (1.29 g, 9.35 mmol),
and 18-crown-6 (0.20 g, 0.76 mmol) in acetone (100 mL) was
refluxed for 18 h. The solvent was evaporated under reduced
pressure and the mixture dispersed in H2O (150 mL) and
stirred for 12 h. Filtration, washing with H2O, drying under
vacuum, and recrystallization from n-hexane afforded
2(4OC12H25) as a white powder. Yield 3.56 g (80%). Anal. Calcd
for C68H112O6Br2 (1184): C, 68.92; H, 9.46. Found: C, 68.94;
In str u m en ta tion . 1H and 13C NMR spectra were obtained
on a Bruker Avance DPX spectrometer at 400 and 100 MHz,
respectively, with deuterated CHCl3 and DMSO with TMS as
internal standard. Gel permeation chromatography (GPC)
measurements were carried out using a Polymer Lab chro-
matographer with two Ultra Styragel linear columns with pore
sizes of 104 and 500 Å, UV detector (254 nm), polystyrene
standards, and CHCl3 as eluent, at 25 °C with a flow rate of
1 mL/min.
Wide-angle X-ray diffraction (WAXS) patterns were recorded
using the X-ray beam with a pinhole collimation and a two-
dimensional detector (Siemens) with 1024 × 1024 pixels. A
double graphite monochromator for the Cu KR radiation (λ )
0.154 nm) was used. The beam diameter was about 0.5 mm,
and the sample-to-detector distance was 80 mm. The recorded
scattered intensity distributions were integrated over the
azimuthal angle and are presented as functions of the scat-
tering vector (s ) 2 sin θ/λ, where 2θ is the scattering angle).
Differential scanning calorimetry (DSC) experiments were
conducted with cooling and heating rates of 10 K/min using a
Mettler 30 calorimeter with a cell purged with nitrogen.
Calibration for the temperature and enthalpy changes was
performed using indium as a standard. The second heating
run is considered as reflecting the properties of the compact
bulk material. Melting and crystallization temperatures (Tm
and Tc, respectively) were determined at the peak maxima or
from the tangent at the Tm peak, as explained in Table 2.
Dynamic mechanical measurements have been performed
using a Rheometrics RMS 800 mechanical spectrometer. Shear
deformation was applied under conditions of controlled defor-
mation amplitude which was changed with temperature
between ∆γ ) 0.0001 at low temperatures and ∆γ ) 0.05 at
high temperatures, always remaining in the range of the linear
viscoelastic response of studied samples. Plate-plate geometry
has been used with plate diameters of 6 mm. The gap between
plates (sample thickness) was about 1 mm. Experiments have
been performed under a dry nitrogen atmosphere. Results are
presented as temperature dependencies of the storage (G′) and
loss (G′′) shear modulus measured at a constant deformation
frequency of 10 rad/s. The results below 50 °C were obtained
1
H, 9.68. H NMR (CDCl3): 0.88 (t, 12H, CH3), 1.26-1.38 (m,
64H, CH3(CH2)8), 1.42 (m, 8H, CH3(CH2)8CH2), 1.77 (m, 8H,
CH3(CH2)8CH2CH2), 3.94 (t, 8H, CH2CH2O), 5 (s, 4H, ArCH2O),
6.4 (t, 2H, dendritic Ar-H), 6.58 (d, 4H, dendritic Ar-H), 7.15
(s, 2H, Ar-H). 13C NMR (CDCl3): 14.46 (CH3), 23.04 (CH3CH2),
26.42 (CH3CH2CH2), 29.61-29.99 (CH3CH2CH2(CH2)7), 32.28
(CH3CH2CH2(CH2)7CH2), 68.52 (CH2CH2O), 72.35 (ArCH2O),
101.50 (OCCHCO), 105.77 (OCCHCCH2O), 111.94 (BrC),
119.66 (BrCCH), 138.70 (CHCCH2O), 150.45 (OCCBr), 160.92
(CH2CH2OCCH).
1,4-Di[3,5-bis(3,5-bis(dodecyloxy)ben zyloxy)ben zyloxy]-
2,5-d ibr om oben zen e (2(8OC12H25)). A mixture of 1 (0.50 g,
1.86 mmol), dendron G2 (4.37 g, 3.91 mmol), K2CO3 (0.64 g,
4.60 mmol), and 18-crown-6 (98.60 mg, 0.37 mmol) in acetone
(80 mL) was refluxed for 24 h. Filtration and evaporation of
the solvent under reduced pressure afforded 2(8OC12H25) as
a viscous oil that crystallized upon standing and was used
without further purification. Yield 3.06 g (70%). 1H NMR
(CDCl3): 0.87 (t, 24H, CH3), 1.26-1.38 (m, 128H, CH3(CH2)8),
1.41 (m, 16H, CH3(CH2)8CH2), 1.76 (m, 16H, CH3(CH2)8-
CH2CH2), 3.93 (t, 16H, CH2CH2O), 4.95 (s, 8H, ArCH2O), 5 (s,
4H, ArCH2O), 6.39 (t, 4H, dendritic Ar-H), 6.56 (m, 10H,

Macromolecules, Vol. 37, No. 10, 2004
Dendronized Macromolecular Architectures 3579
dendritic Ar-H), 6.7 (d, 4H, dendritic Ar-H), 7.15 (s, 2H,
Ar-H). 13C NMR (CDCl3): 14.54 (CH3), 23.11 (CH3CH2),
26.47 (CH3CH2CH2), 29.68-30.09 (CH3CH2CH2(CH2)7), 32.33
(CH3CH2CH2(CH2)7CH2), 68.48 (CH2CH2O), 70.59 (ArCH2O),
72.09 (ArCH2O), 101.21 (OCCHCO), 102.19 (OCCHCO), 106.11
(OCCHCCH2O), 106.29 (OCCHCCH2O), 111.88 (BrC), 119.42
(BrCCH), 138.91 (OCH2CCH), 139.30 (OCH2CCH), 150.34
(OCCBr), 160.55 (CHCOCH2Ar), 160.92 (CH2CH2OCCH).
2′,5′-Di[3,5-bis(d od ecyloxy)ben zyloxy]-p-tr ip h en ylen e-
4′,4′′-d i(tetr a h yd r op yr a n yloxy) (4(4OC12H25)). A mixture
containing 2(4OC12H25) (3.56 g, 3.00 mmol), 3 (2.67 g, 12.03
mmol), Pd(PPh3)4 (0.17 g, 0.15 mmol), toluene (140 mL) and
Na2CO3 (2 M) (15.00 mL, 30.07 mmol) was carefully degassed
and afterward refluxed with vigorous stirring for 24 h.
Separation of the organic layer, filtration, and evaporation
under reduced pressure produced 4(4OC12H25) as a grayish
solid. Yield 3.73 g (90%).1H NMR (CDCl3): 0.88 (t, 12H, CH3),
1.26-1.38 (m, 64H, CH3(CH2)8), 1.43 (m, 8H, CH3(CH2)8CH2),
1.5-2 (three m, 12H, THP-CH2), 1.74 (m, 8H, CH3(CH2)8-
CH2CH2), 3.64 (m, 2H, THP-OCH2CH2), 3.86 (t, 8H, CH2CH2O),
3.92 (m, 2H, THP-OCH2CH2), 4.93 (s, 4H, ArCH2O), 5.46 (t,
2H, THP-OCHO), 6.35 (t, 2H, dendritic Ar-H), 6.45 (d, 4H,
dendritic Ar-H), 7.03 (s, 2H, Ar-H), 7.08 (d, 4H, THPO-Ar-
H), 7.54 (d, 4H, H-Ar-Ar). 13C NMR (CDCl3): 14.53 (CH3),
19.21 (THP: CHCH2CH2), 23.1 (CH3CH2), 25.67 (THP: CH2CH2-
CH2O), 26.49 (CH3CH2CH2), 29.69-30.1 (CH3CH2CH2(CH2)7),
30.83 (THP: CH2CH2CHO), 32.33 (CH3CH2CH2(CH2)7CH2),
62.40 (THP: CH2CH2O), 68.44 (CH2CH2O), 71.91 (ArCH2O),
96.74 (THP: ArO-CHO), 101.22 (OCCHCO), 105.42 (OCCH-
CCH2O), 116.39 (THPOCCHCHCAr), 117.29 (ArCCHCO),
130.93-131.91 (ArCCAr, ArCCAr, ArCCHCHCOTHP), 140.05
(CHCCH2O), 150.55 (OCCHCAr), 156.69 (THPOCCH), 160.73
(CHCOCH2CH2).
4H, H-Ar-Ar). 13C NMR (CDCl3): 14.07 (CH3), 22.65 (CH3CH2),
26.05 (CH3CH2CH2), 29.27-29.65 (CH3CH2CH2(CH2)7), 31.89
(CH3CH2CH2(CH2)7CH2), 68.07 (CH2CH2O), 71.67 (ArCH2O),
100.92 (OCCHCO), 105.12 (OCCHCCH2O), 115.11 (HOCCH-
CHCAr), 117.06 (ArCCHCO), 129.78-130.67 (ArCCAr,
ArCCAr, ArCCHCHCOH), 139.75 (CHCCH2O), 150.26
(OCCHCAr), 155.99 (HOCCH), 160.4 (CHCOCH2CH2).
2′,5′-Di[3,5-b is(3,5-b is(d od ecyloxy)b en zyloxy)b en zyl-
oxy]-p-tr ip h en ylen e-4′,4′′-d iol (5(8OC12H25)). CSA (2.10 g,
9.04 mmol) was added to a solution of 4(8OC12H25) (2.30 g,
0.90 mmol) in THF (40 mL) and MeOH (2 mL), and the
mixture was stirred at room temperature for 18 h. Evaporation
of the mother liquid under vacuum, stirring with MeOH,
filtration, and washing with n-hexane afforded 5(8OC12H25
as a grayish solid. Yield 1.29 g (60%). Anal. Calcd for
156H242O16 (2370): C, 78.99; H, 10.21. Found: C, 78.7; H, 10.5.
)
C
1H NMR (CDCl3): 0.88 (t, 24H, CH3), 1.26-1.39 (m, 128H,
CH3(CH2)8), 1.44 (m, 16H, CH3(CH2)8CH2), 1.78 (m, 16H,
CH3(CH2)8CH2CH2), 3.95 (t, 16H, CH2CH2O), 4.89 (s, 8H,
ArCH2O), 4.95 (s, 4H, ArCH2O), 6.42 (t, 4H, dendritic Ar-H),
6.50 (t, 2H, dendritic Ar-H), 6.55 (d, 4H, dendritic Ar-H),
6.57 (d, 8H, dendritic Ar-H), 6.9 (d, 4H, HO-Ar-H), 7.05 (s,
2H, Ar-H), 7.51 (d, 4H, H-Ar-Ar). 13C NMR (CDCl3): 14.54
(CH3), 23.1 (CH3CH2), 26.45 (CH3CH2CH2), 29.6-30.08
(CH3CH2CH2(CH2)7), 32.33 (CH3CH2CH2(CH2)7CH2), 68.61
(CH2CH2O), 70.32 (ArCH2O), 71.8 (ArCH2O), 101.02
(OCCHCO), 101.1 (OCCHCO), 106.22 (OCCHCCH2O), 106.3
(OCCHCCH2O), 115 (HOCCHCHCAr), 117 (ArCCHCO),
131.22-131.37 (ArCCAr, ArCCAr, ArCCHCHCOH), 139.58
(CHCCH2O), 140 (CHCCH2O), 150.5 (OCCHCAr), 160.32
(HOCCH), 160.79 (CHCOCH2CH2), 160.9 (CHCOCH2Ar).
Gen er a l P olym er iza tion P r oced u r e. A carefully de-
gassed mixture of diol (1.0 mmol), R,ω-aliphatic dibromide (1.0
mmol), TBAH (0.4 mmol), o-DCB (5 mL), and NaOH (10 N) (5
mL) was vigorously stirred at 120 °C under a continuous
stream of argon: P ETH-4OC12H25-x, 2-4 days; P ETH-
8OC12H25-x, 4-8 days. The polymer thus formed was dissolved
in CHCl3 and precipitated in a 10-fold amount of methanol.
Filtration, redissolvance in CHCl3, and a second filtration
afforded the salt-clean desired polymeric sample as white foam
after reprecipitation in methanol or as a self-standing film
after casting.
2′,5′-Di[3,5-b is(3,5-b is(d od ecyloxy)b en zyloxy)b en zyl-
oxy]-p -t r ip h e n yle n e -4′,4′′-d i(t e t r a h yd r op yr a n yloxy)-
(4(8OC12H25)). A degassed mixture of 2(8OC12H25) (3.00 g,
12.80 mmol), 3 (1.14 g, 5.14 mmol), PdCl2(dppf) (0.0563 g,
0.0770 mmol), THF (80 mL), and NaOH (3 M) (51.20 mL, 15.36
mmol) was heated under reflux with vigorous stirring for 48
h. The organic layer was separated and filtrated, and the
solvent was removed under reduced pressure. The product
thus obtained was stirred with methanol, filtrated, and dried
1
under vacuum. Yield 2.30 g (70%). H NMR (CDCl3): 0.87 (t,
P ETH-4OC12H25-x)12. A carefully degassed mixture of diol
5(4OC12H25) (0.500 g, 0.413 mmol), R,ω-aliphatic dibromide x
) 12 (0.136 g, 0.413 mmol), TBAH (0.056 g, 0.165 mol),
o-dichlrobenzene (o-DCB) (1.8 mL), and NaOH (10 N) (1.8 mL)
was vigorously stirred at 120 °C under a continuous stream
of argon for 3 days. The polymer thus formed was dissolved
in CHCl3 and precipitated in a 10-fold amount of methanol.
Filtration, redissolvance in CHCl3, and a second filtration
afforded the salt-free polymeric sample as white foam after
reprecipitation in methanol or as a self-standing film after
casting. Yield 0.60 g (94%) (Table 1, entry 1). 1H NMR
(CDCl3): 0.79 (t, 12H, CH3), 0.94-1.31 (two broad, 88H,
CH3(CH2)9 and CH2(CH2)8CH2), 1.63 (t, 8H, CH3(CH2)9CH2),
1.72 (broad, 4H, CH2(CH2)8CH2), 3.76 (t, 8H, CH2CH2O), 3.89
(broad, 4H, OCH2CH2(CH2)8CH2CH2O), 4.84 (s, 4H, ArCH2O),
6.25 (s, 2H, dendritic Ar-H), 6.35 (s, 4H, dendritic Ar-H), 6.84
(d, 4H, CH2O-Ar-H), 6.93 (s, 2H, Ar-H), 7.45 (d, 4H, H-Ar-
Ar). 13C NMR (CDCl3): 14.54 (CH3), 23.1 (CH3CH2), 26.48
(CH3CH2CH2), 26.6 (OCH2(CH2)4(CH2)2), 29.68-30.1 (CH3-
CH2CH2(CH2)7 and OCH2(CH2)4(CH2)2), 32.33 (CH3CH2CH2-
(CH2)7CH2), 68.41 (CH2CH2O), 71.91 (ArCH2O), 101.19
(OCCHCO), 105.39 (OCCHCCH2O), 114.38 (OCCHCHCAr),
117.23 (ArCCHCO), 130.8-131.03 (ArCCAr, ArCCAr, ArC-
CHCHCO), 140.06 (CHCCH2O), 150.55 (OCCHCAr), 158.75
(OCCHCH), 160.7 (CHCOCH2CH2).
24H, CH3), 1.25-1.38 (m, 128H, CH3(CH2)8), 1.43 (m, 16H,
CH3(CH2)8CH2), 1.5-2 (three m, 12H, THP-CH2), 1.76 (m,
16H, CH3(CH2)8CH2CH2), 3.54 (m, 2H, THP-OCH2CH2), 3.83
(m, 2H, THP-OCH2CH2), 3.93 (t, 16H, CH2CH2O), 4.85 (s, 8H,
ArCH2O), 4.96 (s, 4H, ArCH2O), 5.36 (t, 2H, THP-OCHO),
6.39 (t, 4H, dendritic Ar-H), 6.50 (t, 2H, dendritic Ar-H), 6.53
(d, 8H, dendritic Ar-H), 6.57 (d, 4H, dendritic Ar-H), 7.05
(s, 2H, Ar-H), 7.1 (d, 4H, THPO-Ar-H), 7.57 (d, 4H, H-Ar-
Ar). 13C NMR (CDCl3): 14.52 (CH3), 20.60 (THP: CHCH2CH2),
23.09 (CH3CH2), 25.64 (THP: CH2CH2CH2O), 26.45 (CH3CH2-
CH2), 29.31-30.07 (CH3CH2CH2(CH2)7), 31.10 (THP: CH2CH2-
CHO), 32.32 (CH3CH2CH2(CH2)7CH2), 64.23 (THP: CH2CH2O),
68.48 (ArCH2O), 68.63 (CH2CH2O), 70.32 (ArCH2O), 95.08
(THP: ArO-CHO), 101.03 (OCCHCO), 101.22 (OCCHCO),
105.90 (OCCHCCH2O), 106.22 (OCCHCCH2O), 115.44 (THPOC-
CHCHCAr), 116.39 (ArCCHCO), 130.80-131.24 (ArCCAr,
ArCCAr, ArCCHCHCOTHP), 139.61 (CHCCH2O), 140.25
(CHCCH2O), 150.62 (OCCHCAr), 155.57 (THPOCCH), 160.35
(CHCOCH2Ar), 160.81 (CHCOCH2CH2).
2′,5′-Di[3,5-bis(d od ecyloxy)ben zyloxy]-p-tr ip h en ylen e-
4′,4′′-d iol (5(4OC12H25)). Camphorosulfonic acid (CSA) (6.30
g, 27.12 mmol) was added to a solution of 4(4OC12H25) (3.73
g, 2.70 mmol) in THF (50 mL) and MeOH (3 mL), and the
mixture was stirred at room temperature for 18 h. Precipita-
tion with MeOH, filtration, and washing with n-hexane
afforded a white solid, 5(4OC12H25). Yield (75%). Anal. Calcd
for C80H120O8 (1210): C, 79.34; H, 10.08. Found: C, 78.93; H,
10.21. 1H NMR (CDCl3): 0.88 (t, 12H, CH3), 1.26-1.38 (m,
64H, CH3(CH2)8), 1.4 (m, 8H, CH3(CH2)8CH2), 1.74 (m, 8H,
CH3(CH2)8CH2CH2), 3.86 (t, 8H, CH2CH2O), 4.93 (s, 4H,
ArCH2O), 6.35 (t, 2H, dendritic Ar-H), 6.43 (d, 4H, dendritic
Ar-H), 6.86 (d, 4H, HO-Ar-H), 7.01 (s, 2H, Ar-H), 7.50 (d,
P ETH-8OC12H25-x)12. A carefully degassed mixture of diol
5(8OC12H25) (0.200 g, 0.084 mmol), R,ω-aliphatic dibromide x
) 12 (0.027 g, 0.084 mmol), TBAH (0.012 g, 0.035 mmol),
o-DCB (0.4 mL), and NaOH (10 N) (0.4 mL) was vigorously
stirred at 120 °C under a continuous stream of argon for 8
days. The polymer thus formed was dissolved in CHCl3 and
precipitated in a 10-fold amount of methanol. Filtration,
redissolvance in CHCl3, and a second filtration afforded the

3580 Andreopoulou et al.
Macromolecules, Vol. 37, No. 10, 2004
F igu r e 1. 1H NMR spectra of P ETH-4OC12H25-x)12 (inset) and of P ETH-8OC12H25-x)12.
salt-free polymeric sample as white foam after reprecipitation
in methanol or as a self-standing film after casting. Yield 0.20
g (88%) (Table 1, entry 6). 1H NMR (CDCl3): 0.87 (t, 24H, CH3),
1.26-1.44 (two broad, 160H, CH3(CH2)9 and CH2(CH2)8CH2),
1.72-1.79 (two broad, 20H, CH3(CH2)9CH2 and CH2(CH2)8CH2),
3.86 (broad, 4H, OCH2CH2(CH2)8CH2CH2O), 3.92 (t, 16H,
CH2CH2O), 4.85 (s, 8H, ArCH2O), 4.97 (s, 4H, ArCH2O), 6.4
(s, 4H, dendritic Ar-H), 6.49 (s, 2H, dendritic Ar-H), 6.53 (d,
8H, dendritic Ar-H), 6.57 (s, 4H, dendritic Ar-H), 6.94 (d,
4H, CH2O-Ar-H), 7.05 (s, 2H, Ar-H), 7.56 (d, 4H, H-Ar-
Ar). 13C NMR (CDCl3): 14.4 (CH3), 23.08 (CH3CH2), 26.45
(CH3CH2CH2 and OCH2(CH2)4(CH2)2), 29.67-29.97 (CH3-
CH2CH2(CH2)7 and OCH2(CH2)4(CH2)2), 32.26 (CH3CH2CH2-
(CH2)7CH2), 68.52 (CH2CH2O), 70.6 (ArCH2O), 72.06 (ArCH2O),
101.42 (OCCHCO), 102.23 (OCCHCO), 106.1 (OCCHCCH2O),
106.29 (OCCHCCH2O), 114.5 (OCCHCHCAr), 117.45 (ArC-
CHCO), 130.82-131.22 (ArCCAr, ArCCAr, ArCCHCHCO),
139.45 (CHCCH2O), 140.3 (CHCCH2O), 150.76 (OCCHCAr),
158.9 (OCCHCH), 160.47 (CHCOCH2Ar), 160.95 (CHCOCH2-
CH2).
solid-state conformational behavior and determining
whether this kind of dendrons would dominate any
organizational features in the final polymeric materials.
In general, the alkoxy dendritic fragments employed
up to now in the literature were usually 3,4,5-, 3,4-, or
4-substituted ones. A combination of these kinds of
dendrons with the 3,5-disubstituted benzyl ethers of the
Fre´chet type was also made in an effort to discriminate
variations between the different dendritic structures.23
Also, in this case the flexible chains led to a similar
arrangement of the dendrons like in the former cases.
However, an investigation of dendronized polymers
bearing dendrons of the Fre´chet-type periphery deco-
rated with lengthy alkoxy groups, rising from poly-
merization conditions other than chain-growth ones, has
been only once attempted so far, but their investigation
referred strictly to the optical properties of the conju-
gated main polymeric backbones.15
Following a macromonomer approach that has proven
to be extremely efficient for the syntheses of oligo-
phenylene-dendronized macromonomers, we originally
prepared, using the convergent methodology,24 aromatic
dibromides bearing side dendrons10 of the first or second
generation, respectively, decorated with dodecyloxy
periphery end groups (Scheme 1). The dibromides 2(G1)
) 2(4OC12H25) and 2(G2) ) 2(8OC12H25) were then
coupled with the tetrahydropyran (THP) protected hy-
Resu lts a n d Discu ssion
Mon om er a n d P olym er Syn th eses. In light of some
of our previous findings,21 we anticipated that aromatic-
aliphatic dendronized polyethers bearing two alkoxy
functionalized side dendrons onto every repeating unit
would provide soluble, high molecular weight, film
forming materials with interesting bulk properties.
Furthermore, we were interested in exploiting their

Macromolecules, Vol. 37, No. 10, 2004
Dendronized Macromolecular Architectures 3581
droxyl phenylboronic acid (3)21 under palladium-medi-
ated Suzuki coupling conditions.25 Removing the THP
end protecting groups in a mild acidic environment
finally produced the hydroxy end functionalized ter-
phenyl diols of the first or second generation carrying
the two side dendrons in their middle phenylene ring,
5(4OC12H25) and 5(8OC12H25), respectively. These final
macromonomer diols were subsequently polymerized
under phase transfer conditions26 with R,ω-aliphatic
dibromides of various lengths (Scheme 2). High molec-
ular weight polyethers were obtained in most cases as
depicted from their GPC results using a PS standard
calibration (Table 1), with good solubilities in common
chlorinated solvents for both the first and second
generation polyethers. The first generation alkoxy-
functionalized polyethers, P ETH-4OC12H25-x, are more
soluble in milder solvents like chloroform than the
analogous ones bearing side dendrons of the Fre´chet
type.21 However, the true molecular weights of these
polymeric materials should be higher by at least a factor
of 2, since GPC determination using PS standards
underestimates their actual molecular characteris-
tics.3,9,21,27 Their 1H and 13C NMR characterization is
in full agreement with the proposed structures, and
moreover no end groups were detectable throughout the
polymeric main chains proving the efficiency of the
polymerization conditions employed (Figure 1).
Th er m a l a n d Solid -Sta te P r op er ties. The initial
characterization of polyethers bearing first generation
dendrons P ETH-4OC12H25-x has been performed by
means of the differential scanning calorimetry (DSC).
Parts a and b of Figure 2 show the representative
thermograms recorded during heating and cooling,
respectively. For comparison, the DSC thermogram of
the macromonomer diol 5(4OC12H25) is shown in Figure
2d. Intense melting (Tm) and crystallization (Tc) transi-
tions (see Table 2) were observed for all polymeric
samples, but no glass transition temperatures were
noticeable for any of them. On the other hand, diol
5(4OC12H25) exhibited two transitions (Figure 2d)
observed both during heating and cooling, indicating a
mesophase in the temperature range between ∼60 and
∼120 °C, which separates the crystalline and isotropic
states situated at lower and higher temperatures,
respectively. Whereas, in the diol, the melting or
crystallization DSC peaks are sharp and nearly sym-
metric, the polymers’ endothermic transitions are highly
asymmetric and considerably broadened on the low-
temperature side. This kind of behavior is characteristic
for systems which show a partial melting consisting of
dismounting or rearranging structures of various ther-
mal stability. Most of the thermograms presented in
Figure 2a indicate such premelting or structural reor-
ganization taking place at temperatures extending
much below the main melting peak. This effect extends
to temperatures below the room temperature, which
means that samples kept at normal conditions have a
fraction of material, which could crystallize when cooled
down or when conditions are created for formation of
more thermally stable structures.
F igu r e 2. DSC thermograms of P ETH-4OC12H25-x samples:
(a) second heating runs, (b) first cooling runs, (c) after aging
of the samples at room temperature for 3 months, first heating
run, and (d) of the corresponding macromonomer diol 5-
(4OC12H25).
seen, one at the lower temperature region (Tm ) and a
a
second one at the region of the initially observed main
endothermic transitions (Tm).
The melting (Tm) and crystallization (Tc) tempera-
tures are dependent on the number of methylene units
(x) along the main-chain flexible spacer, as depicted in
Figure 3. On the other hand, the new transition Tm
,
which appears just above the temperature of samplae
storage, seems to be independent of x. The fact that this
additional melting observed only after a kind of aging
does not depend on x indicates that it should be related
to melting of material fractions which became ordered
in a secondary crystallization process requiring a lot of
time and creating structures stable just at and slightly
above the samples’ storage temperature.
The main transitions (Tm, Tc) were also observed
using polarized optical microscopy (POM) where the
growth of spherulites throughout the polymeric samples
was detected during cooling from the isotropic melt (2
°C/min). This indicated that the structure formation in
the polymers goes by nucleation and growth, which
usually can be strongly influenced by cooling rates or
temperature of an isothermal process. Employing small-
angle light scattering (SALS)22 under the same condi-
tions as for the POM experiments, scattering patterns
characteristic for the spherulites were observed under
crossed (Hv) polarizers. The size of the spherulites was
estimated to vary in the range between 3 and 9 µm with
a tendency of decreasing spherulites’ size (higher nucle-
Taking this into account, the same polymeric samples
were also examined, using the same testing conditions
after keeping them for three months at room temper-
ature in order to determine possible formation of
secondary structures due to additional slow relaxations.
For the samples aged in the above-described way
(Figure 2c), two well-resolved endothermic peaks were

3582 Andreopoulou et al.
Macromolecules, Vol. 37, No. 10, 2004
F igu r e 3. Variation of the transition temperatures as deter-
mined from the DSC experiments (Table 2) vs the number of
methylene units along the main polymeric chain x, for P ETH-
4OC12H25-x samples. Second heating: Tm, 9; Tc, 2. After aging
at room temperature for 3 months: Tm , O; Tm, 0; Tc, 4.
a
F igu r e 5. DSC thermograms of (a) P ETH-8OC12H25-x)12
first and second heating cycle and first cooling cycle and (b)
macromonomer diol 5(8OC12H25).
the thermogram of the corresponding macromonomer
diol 5(8OC12H25) (Figure 5b). A complex first heating
curve was obtained for P ETH-8OC12H25-x)12 while
only one exothermic peak was observed during cooling
followed by a much simpler second heating curve. The
macromonomer diol 5(8OC12H25) showed only one endo-
thermic transition during the first heating with no
crystallization or melting transitions during the follow-
ing cycles. After remaining at room temperature for
some days the same diol sample again presented only
one first endothermic peak, revealing a difficulty toward
crystallization.
Dynamic mechanical measurements for polymers
P ETH-4OC12H25-x were performed for the evaluation
of their properties under shear deformation in a broad
temperature range. Temperature sweep tests were
conducted during both heating and cooling of the
polymeric samples. Figure 6 shows the results obtained
during cooling for samples with various spacer lengths
(Figure 6a) and during cooling and heating for one
sample with x ) 11 (Figure 6b). As expected, pronounced
changes of the storage and loss shear moduli (G′ and
G′′, respectively) were observed during crystallization
or melting of the polymers. These changes demonstrate
the transition between the polymers’ solid and liquid
like states. From the above experiments the Tm and Tc
temperatures were also determined which revealed the
same dependencies on x as was initially detected during
their DSC tests (see Figure 3). Another interesting
feature in the G′ and G′′ curves is the existence of small
changes in their slopes in the temperature region at
about 50 °C, probably indicating an onset of mobility
related to partial melting of the secondary crystallized
material, in agreement with the observations made by
means of DSC for the aged samples.
F igu r e 4. POM picture (a) and the SALS pattern (b) corre-
sponding to P ETH-4OC12H25-x)11 at room temperature. The
white bar in (a) represents a size of 100 µm. The intensity
distributions in (b) are recorded at 45° with respect to
polarization directions in the Hv pattern.
ation density) with increasing spacer length x. An
example of the Hv scattering pattern and some intensity
distributions allowing determination of spherulites’ size
are presented in Figure 4.
For polyethers bearing second generation alkoxy side
dendrons, a representative DSC thermogram is given
in Figure 5a for P ETH-8OC12H25-x)12 together with
Polyethers carrying either first (4OC12H25) or second
(8OC12H25) generation side dendrons have shown an
interesting property of forming stable, self-standing
films after melt-pressing or casting from chloroform

Macromolecules, Vol. 37, No. 10, 2004
Dendronized Macromolecular Architectures 3583
F igu r e 6. Temperature dependencies of the real (G′, filled symbols) and imaginary (G′′, open symbols) parts of the complex
shear modulus for PETH-4OC12H25-x samples [x ) 12 tilted 2, 4; x ) 11 b, O; x ) 10 9, 0; x ) 9 f, g; x ) 8 1, 3] (a) during
cooling from the melt and (b) during cooling (2, 4) and heating (b, O) obtained for the P ETH-4OC12H25-x)11 sample.
F igu r e 8. Distances corresponding to the first intensive peak
in the diffraction from P ETH-4OC12H25-x samples as a
function of the number of repeating units in the flexible
backbone spacer. For comparison, lengths of extended repeat-
ing units in the simulated backbones are shown.
F igu r e 7. X-ray diffraction intensity distributions for P ETH-
4OC12H25-x samples in film form as casted from CHCl3
solutions.
intensity distributions recorded along the equatorial and
meridional directions corresponding to the annealed
sample are presented in Figure 9. These patterns
indicate a clear ordering along the drawing direction,
as well as in the perpendicular one. The meridional
reflections correspond to the periodicity of the chains
oriented along the drawing direction. In the annealed
sample (Figure 9b), a large number of higher-order
reflections indicate a high uniformity in the chain
periodicity and related supramolecular structure. The
equatorial reflections demonstrate the lateral ordering
of the aligned and extended chains into a layered
structure. Annealing of the oriented sample was per-
formed at 50 °C, which is close to the polymers’ crystal-
lization temperature, leading to an improved order as
illustrated in Figure 9b. Changes such as the develop-
ment of more higher-order reflections in the meridional
direction and the more or less loss of its wider-angle
amorphous halo, while simultaneously changes of the
preexisting diffractions from a linear to a more spherical
shape, are clearly observed, pointing out a better
molecular organization in the annealed sample.
solutions. These films were investigated employing
wide-angle X-ray scattering (WAXS) at room tempera-
ture. The results indicate quite complex self-organiza-
tion effects depending on both the parameters of the
molecular structure and conditions of sample treatment.
As an example, Figure 7 shows the scattered intensity
distributions recorded for all P ETH-4OC12H25-x samples
in film form. The experiments were in this case per-
formed with the X-ray beam perpendicular to the film
surface. Intense diffraction peaks were detected in the
small-angle region and were accompanied by weaker
diffraction peaks and an amorphous halo in the wide-
angle region. Distances corresponding to the intense
small-angle diffraction have made impression to be
correlated with the length of the flexible repeating unit
in the polymeric backbone. In Figure 8, these distances
are compared with the simulated dimensions of fully
extended repeating units along the backbone (Chem 3D
Ultra 7.0). For an even number of methylene units in
the flexible backbone spacer, the experimentally de-
tected distances nearly reach the extended ones. Poly-
mers with an odd number of units in the spacer do not
follow this tendency, however, an explanation of that
requires further investigation. The assignment of the
low-angle peak to the periodicity along the backbone
was also supported by analysis of the 2D diffraction
patterns recorded for samples oriented by drawing at
temperatures close to their crystallization temperature.
An example of such patterns can be viewed in parts a
and b of Figure 9 for an as-drawn and annealed fiber of
P ETH-4OC12H25-x)12, respectively. Additionally, the
Also, in the case of the second generation polymeric
films, ordered structures were detected. An example of
a diffraction pattern for polyether P ETH-8OC12H25
-
x)12 is given in Figure 10. The pattern was obtained
from a drawn film with the drawing direction vertical.
The diffraction also in this case indicates ordering both
along the drawing direction and in the direction lateral
with respect to the oriented polymeric chains. A com-
parison of correlation distances corresponding to the
meridional and equatorial peaks revealed that ordering

3584 Andreopoulou et al.
Macromolecules, Vol. 37, No. 10, 2004
F igu r e 10. 2D X-ray diffraction pattern and corresponding
equatorial and meridional intensity distributions of an oriented
sample of P ETH-8OC12H25-x)12.
with the same length of flexible spacer, but the distances
indicated by the equatorial reflections became larger by
a factor nearly reflecting an increase of the side groups
molecular mass. This shows that, also in the case of
polyethers with higher generation side dendrons, the
backbones assume a nearly extended conformation, and
their lateral ordering is controlled by the size of the side
dendrons.
From the above results, even though a much detailed
investigation is intended, some first conclusions over the
organization of these dendronized polymeric materials
can be extracted. A consideration concerning the struc-
ture in oriented filaments is based on a qualitative
analysis of the diffractograms presented in Figure 9. We
assume that the structure in such oriented states is
controlled primarily by chain extension along the axes
of the filaments but also by the mesogenic character of
the terphenyl segments equidistantly distributed along
the polymer backbones and by the packing possibilities
of the complex units to a bulk material. To simplify
further discussion, we map the studied molecular
structures by the simple scheme of the generalized
repeating unit as shown in Figure 11. J oining such units
to a polymer results in a structure presented schemati-
cally on the right-hand side of the figure. Such simpli-
fied polymers are used in Figure 12 to represent
macromolecular arrangements, which could lead to the
observed scattering patterns. Two most probable, in our
opinion, local arrangements are presented. In one case
(structure A, Figure 12), an assembly of well-extended
polymer chains with backbones separated into layers
and the mesogenic units forming a nematic 2D meso-
phase within the layers is considered. Such a structure
contributes to scattering effects dependent on the
orientation of the volume element with respect to the
incident X-ray beam. We consider two characteristic
situations leading to diffractions reflecting the main
features of the structure. With the chains oriented
vertically (c axis) and the X-ray beam nearly perpen-
dicular to the backbone layers (a axis), the scattering
F igu r e 9. 2D X-ray diffraction pattern of an oriented sample
of P ETH-4OC12H25-x)12 before (a) and after (b) annealing.
Two intensity distributions measured along the equatorial and
meridional directions in pattern (b) are shown. The directions
are indicated in the pattern (b) by dashed horizontal and
vertical lines, respectively. Positions of intensity maxima in
the meridional intensity distribution satisfied the ratios
indicated in the figure. For the discussion of this effect see
the text.
along polymeric backbones has nearly the same peri-
odicity as was observed for the first generation polymers

Macromolecules, Vol. 37, No. 10, 2004
Dendronized Macromolecular Architectures 3585
F igu r e 11. Schematic representation of the monomer and the
polymer with distinctions only of the most important archi-
tectural units.
F igu r e 13. Schematic representation of the 2D fiber scatter-
ing pattern with contributions of effects related to both
structures considered in Figure 12. The reflections containing
information about the dimensions da, db, and dc in the real
space are indicated.
within the backbone layers is taken into account, for
which the resulting scattering pattern (B1) exhibits a
series of meridional spots which indicate the period of
the correlations along the backbone. The number of
higher-order reflections in this case can be correlated
with extension of the order in the direction of the
oriented chains and the horizontal width of the reflec-
tions with the extension of order in the transversal
direction.
With the beam nearly parallel to the backbone layers
(b axis), the diffraction pattern (A2) reflects the inter-
layer period in the form of the equatorial reflections.
For both structures considered this effect is supposed
to be similar. Again here, depending on the range and
perfection of layered correlations, the number of higher-
order equatorial reflections would be influenced. Lack
of higher-order reflections means a short-range correla-
tion only. For the layered structure considered, the
interlayer spacing should be proportional to the size of
the side groups (in this case dendrons) when the
extension and constitution of the backbones remain
constant. The fact that in these systems the proportion-
ality is nearly preserved with the variation of dendrons’
generations constitutes a strong argument for the
layered structures in the studied materials.
The two cases of order presented in Figure 12 seem
to appear exclusively or simultaneously in the studied
samples, depending on the architectural details and on
the thermal treatment. For example, the as-drawn
sample (Figure 9a) can be considered as having the
structure with the nematic order within the backbone
layers (structure A, Figure 12) predominantly. Anneal-
ing of the drawn sample seems to involve a transforma-
tion of this structure to the smectic one (structure B,
Figure 12). However, in the observed case (Figure 9b),
the transformation is not complete so that the scattering
pattern consists of contributions of the two types of
order. A schematic representation of such a pattern is
shown in Figure 13. It contains a superposition of all
effects illustrated separately in Figure 12. The equato-
rial reflections in the small- and wide-angle range in
this pattern reflect the interlayer and backbone-
backbone correlation periods, respectively. They can be
considered as not distinguishably similar in the two
F igu r e 12. Schematic illustration of the two types of local
order postulated for the drawn polymers and corresponding
scattering effects dependent on the orientation of the structure
with respect to the incident X-ray beam. The structures consist
of the main-chain layers separated by the side groups (den-
drons) and differ by the type of arrangement within the main-
chain layers: A, nematic; B, smectic.
will reflect mainly the organization within these layers.
In the considered case of nematic order, characteristic
sets of meridional and equatorial reflections are ex-
pected (pattern A1) which should indicate periodicities
along the backbone and in the transversal direction,
respectively. Because of only single-chain correlations
assumed, the meridional reflections have a specific
shape (extended in the horizontal direction).28 The
equatorial spots are considered as indicating the back-
bone-backbone correlations within the layers. In the
second case (structure B, Figure 12), a smectic-like order

3586 Andreopoulou et al.
Macromolecules, Vol. 37, No. 10, 2004
postulated structures. In the meridional direction, the
effects of periodicities along the backbones, different for
the two discussed structures, overlap so that the shape
and position of the small-angle reflection may not
effectively fit to the higher-order reflections character-
istic for the structure B (see Figure 12). Such a pattern
is in our opinion in a good qualitative agreement with
the one observed for the annealed polymer (Figure 9b).
The assumed superposition of the scattering from the
two structures explains the initially somewhat puzzling
effect of discrepancy of the position of the first meridi-
onal intensity maximum from the sequence constituting
ratios 1, 2, 3, etc., with the higher-order meridional
intensity maxima which, on the other hand, starting
form the second peak satisfy the ratios 2, 3, 4, etc. (see
Figure 9).
According to the above arguments, a layered structure
consisting of main polymeric backbones with the side
dendritic moieties filling the space between neighboring
layers is the most probable organizational pattern for
these dendronized polyethers. The length of the flexible
spacer in the backbone, distinguishing for these series,
appears as a parameter that can introduce large changes
in the final polymeric properties. Moreover, the struc-
tural motives observed here seem to be unique also in
comparison with other SCDPs consisting of macro-
molecules having some analogous elements in their
architectures. For example, they differ considerably
from the bulk structures of Schlu¨ter’s dendronized
polymers3 for which the dendrons form cylindrical
coatings around the backbones leading to amorphous
assemblies of the flexible cylinders in bulk.29 They also
differ from densely substituted polyesters30 or poly-
paraphenylenes,31 in which despite the frequently ob-
served well-developed layered structures, no comparable
ordering along the backbones has been detected.
high molecular weight, soluble polymers to be obtained
with excellent film forming properties. These particular
dendronized polyethers showed a high tendency toward
self-organization, as indicated by the results of various
experimental techniques (DSC, POM, SALS, and WAXS).
Their bulk characteristics were also examined under
shear deformation conditions, which provided informa-
tion for their mechanical properties. The results indi-
cated a relatively strong dependence of melting and
crystallization temperatures on rather small variation
of the polymeric structure, in particular by varying the
number of methylene units along the main-chain flex-
ible spacer. The polymers have shown an ability to form
macroscopically well-oriented structures as indicated by
means of X-ray diffraction. A layered structure consist-
ing of main-chain polymeric backbones with the side
dendritic moieties occupying the space in between can
be concluded for all the examined systems with various
parameters of the main-chain’s and the side-dendrons’
architectures affecting the final organizational charac-
teristics. The LC type of ordering of the extended
backbones within the main-chain layers is postulated
and can be considered as nematic or smectic depending
on details of the molecular parameters and thermal
treatment.
Ack n ow led gm en t. The authors are indebted to
Prof. G. Wegner (MPIP-Mainz) for helpful discussions
and suggestions. This work was partially supported by
the Marie-Curie-Training Site “Methods of Polymer
Characterization” HPMT-CT-2000-00015 and by the
Operational Programme for Education and Initial Vo-
cational Training on “Polymer Science and Technology”
3.2a, 33H6, administered through the Ministry of
Education in Greece.
Refer en ces a n d Notes
Moreover, it is worth noticing that when going from
a flexible main polymeric backbone to a semirigid one,
we obtained different organizational patterns than those
so far reported for alkoxy functionalized dendronized
polymeric materials, such as polystyrene. Actually,
Percec’s main-chain flexible polymers self-organize
strictly due to the favorable arrangement of the side
dendrons in LC phases, producing mostly hexagonal-
columnar arrays.16
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