Lightly branched comb polyesters: Application in fast drying solvent-borne coating formulations

Article abstract of DOI:10.1016/j.reactfunctpolym.2013.01.008

Novel oxazoline-based comb-polymers possessing linoleyl or oleic side chains have been synthesized and used to produce low viscosity coatings. Inclusion of the polymers in model paint formulations results in coatings that exhibit faster drying times than commercially available alkyd resin formulations. The comb polymers were produced from diol substituted oxazoline monomers that were synthesized through a scalable, solvent free protocol and purified by simple recrystallisation. Co-polymerisation of the oxazolines with adipic acid at 160 °C in the bulk resulted in the targeted polyester comb type polymers. The polymers were soluble in a range of organic solvents and compatible with commercial alkyd resins. Model paint formulations containing up to 40 wt% of the linoleyl-based comb polymers exhibited a dramatic reduction in viscosity (from 35 to 13 Poise at 25 °C) with increasing quantities of polymer added. Dynamic mechanical analysis (DMA) studies revealed that the drying rate of the model paint formulations containing the comb polymers was enhanced when compared with that of commercial alkyd resins.

Full text of DOI:10.1016/j.reactfunctpolym.2013.01.008

Reactive & Functional Polymers 73 (2013) 619–623
Contents lists available at SciVerse ScienceDirect
Reactive & Functional Polymers
journal homepage: www.elsevier.com/locate/react
Lightly branched comb polyesters: Application in fast drying solvent-borne
coating formulations
Ge Cheng a, Barnaby W. Greenland a, Chris Lampard b, Neal Williams b, Malkit S. Bahra b, Wayne Hayes a,
⇑
a Department of Chemistry, University of Reading, Whiteknights, Reading, Berkshire RG6 6AD, UK
b AkzoNobel Ltd., Wexham Road, Slough, Berkshire SL2 5DS, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel oxazoline-based comb-polymers possessing linoleyl or oleic side chains have been synthesized and
used to produce low viscosity coatings. Inclusion of the polymers in model paint formulations results in
coatings that exhibit faster drying times than commercially available alkyd resin formulations. The comb
polymers were produced from diol substituted oxazoline monomers that were synthesized through a
scalable, solvent free protocol and purified by simple recrystallisation. Co-polymerisation of the oxazo-
lines with adipic acid at 160 °C in the bulk resulted in the targeted polyester comb type polymers. The
polymers were soluble in a range of organic solvents and compatible with commercial alkyd resins.
Model paint formulations containing up to 40 wt% of the linoleyl-based comb polymers exhibited a
dramatic reduction in viscosity (from 35 to 13 Poise at 25 °C) with increasing quantities of polymer
added. Dynamic mechanical analysis (DMA) studies revealed that the drying rate of the model paint for-
mulations containing the comb polymers was enhanced when compared with that of commercial alkyd
resins.
Received 17 October 2012
Received in revised form 8 January 2013
Accepted 12 January 2013
Available online 22 January 2013
Keywords:
Oxazoline
Fatty acid
Comb polymers
Polyester
Alkyd coatings
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
cient crosslinking during curing by reaction of their numerous of
surface functional groups [7–15]. Within the family of branched
Reducing emissions of volatile organic compounds (VOCs) from
paint formulation has received increasing attention in recent years,
as a consequence of environmental concerns and the potential risks
to human health assigned to prolonged exposure [1,2]. For example,
recent legislation concerning VOC (in Europe 2010) requires a max-
imum level of 300 g/L [3], effectively eliminating many generations
of solvent borne coatings from the market place. Therefore, there is
a strong demand for new air drying resins to improve upon more
conventional alkyd resin technologies which are now reaching, or
have indeed reached the end of their product lifecycle.
Advances in polymer synthesis in the previous three decades
have resulted in robust strategies to produce polymers with con-
trolled molecular weights and branched structures on an industrial
scale. Notable advances in coating applications include the synthe-
sis of branched polymers (BPs) [4,5]. The compact nature of BPs re-
sults in high numbers of surface functional groups along with
lower viscosity compared to conventional linear polymers [6,7].
These unique structural attributes make branched structures
intriguing candidates as coating additives as they may serve to re-
duce the viscosity of the product formulation which, in turn, could
lower the quantity of VOC thinner required whilst promoting effi-
polymers, numerous specific structures including combs [16],
comb-on-comb [17] and arborescent polymers [18–23] also exhi-
bit similar advantageous physical properties.
In this study, comb-type polymers were targeted that contain
repeat units with reactive fatty acid side-groups. These polymers,
which consist of a linear backbone with numerous lengthy side
chains, exhibit rheological properties that are more comparable
to hyperbranched polymers rather than conventional linear ana-
logues [24–26]. As a consequence of this useful property, comb-
shaped polymers have been employed in developing low viscosity
and rapid drying organic coatings. Recent studies by Athawale
et al. produced comb-type acrylic copolymers for surface coatings
applications that exhibited lower viscosities and reduced drying
times when compared to linear acrylic copolymers [27].
Another possible strategy based on comb polymer technology is
blending commercial alkyds with comb polymers. Talroze et al.
demonstrated that comb polymers can be used as flow modifiers
for thermoplastic polymers [28]. It was shown that a dramatic de-
crease in blend viscosity could be achieved if the length of the side
chains of comb polymers were less than the critical entanglement
limit.
In this study, easily accessed lightly branched comb-structured
polyesters containing oxazoline units as linker groups to reactive
fatty acid side chains have been synthesized and fully character-
⇑
Corresponding author. Tel.: +44 118 378 6491; fax: +44 118 378 6331.
E-mail address: w.c.hayes@reading.ac.uk (W. Hayes).
1381-5148/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.reactfunctpolym.2013.01.008

620
G. Cheng et al. / Reactive & Functional Polymers 73 (2013) 619–623
ised. Blending studies of these materials with commercial alkyd
resins has resulted in new formulations that exhibit more rapid
drying than comparable commercial coating formulations.
(w) ꢀ 0.310 mm (h)). Dynamic mechanical analysis was conducted
with DUPONT DMA 983 DMA (with fixed frequency: 1 Hz) operat-
ing in a shearing mode (isotherm 30 °C for 3 days). All the DMA
data were collected and processed on Universal Thermal Analysis
Software.
2. Experimental
2.2. Small molecule synthesis and characterisation
2.1. Materials and physico-chemical characterisation
2.2.1. Monomer 1
Oleic acid, linoleic acid, dicyclohexylcarbodiimide (DCC), 4-
(dimethylamino)pyridine (DMAP), triethyl amine, tris(hydroxy-
methyl)aminomethane (THAM), adipic acid, and N,N0-dimethyl-
formamide (DMF) were purchased from Aldrich. Tetrahydrofuran
(THF), dimethyl sulfoxide (DMSO), dichloromethane (CH2Cl2),
methanol, acetone and 2-propanol were purchased from Fisher.
Low odour white spirit (Exxsol D40 ex-Total), anti-skinning agent,
methyl ethyl ketone oxime (MEKO ex-Elementis Pigments), and
driers including Octa-soligen 10 (cobalt carboxylate 58%, naptha
40% and methoxy propoxy propanol 2%), Octa-soligen calcium 10
(calcium carboxylate 45% and naptha 55%) and Octa-soligen zirco-
nium 18 (zirconium 2-ethyl hexanoate 56% and naptha 44%) were
used as supplied by OMG Borchers. The alkyd used (a soy oil based
alkyd with 70 wt% in low odour white spirit) was obtained from
Cray Valley Ltd. Melting points were carried out with Stuart Melt-
ing Point Apparatus (SMP10) (UK). 250 MHz 1H and 62.5 MHz 13C
NMR spectra were recorded on Bruker AC250 spectrometer. Infra-
red (IR) spectroscopic analyses were performed on a Perkin Elmer
1720-X Infrared Fourier Transform spectrometer on KBr discs using
thin film. GPC was performed with Polymer Laboratories PL-GPC
120 with PL-AS-MT autosampler fitted with columns (PLgel guard
Into a three-armed round bottomed flask was added oleic acid
(86.00 g, 264 mmol) and tris(hydroxymethyl)aminomethane
(THAM) (32.00 g, 264.00 mmol). The flask was degassed with nitro-
gen and heated slowly to 160 °C with vigorous stirring under a
high flow rate of nitrogen to remove the water formed during
the reaction. After being stirred for 48 h at 160 °C, the mixture
was cooled down to 80 °C and slowly poured into acetone
(1500 mL) with stirring. The solution was maintained at room tem-
perature while a white solid formed which was collected by filtra-
tion and recrystallised from acetone to afford 1 as a white powder
(61.13 g, 63%). M.p.: 72–74 °C; FTIR (KBr, cmꢁ1): 3350 (OH), 3051,
2924, 2851, 1658 (oxazoline ring), 1464 (symmetric COO-stretch-
ing), 1366, 1264, 1030, 989, 741. 1H NMR (250 MHz, CDCl3): d
0.88 (t, J = 7.5 Hz, 3H), 1.30 (br, 20H), 1.61 (m, 2H), 2.02 (m, 4H),
2.29 (t, J = 7.5 Hz, 2H), 3.45 (brs, 2H), 3.63 (ABq, J = 12.5 Hz, 4H),
4.15 (s, 2H), 5.35 (m, 2H). 13C NMR (62.5 MHz, CDCl3): d 14.5,
23.1, 26.5, 27.6, 27.6, 28.7, 29.5–29.9 (6C), 30.12, 30.16, 32.3,
65.3, 72.2, 76.1, 130.1, 130.6, 171.2. CI-MS calcd. for C22H41NO3
367.3086, found 367.3090.
plus 2 ꢀ mixed bed-D, 30 cm, 5
lm) in conjunction with refractive
2.2.2. Monomer 2
index (with differential pressure and light scattering) detector
using THF as the eluent at 30 °C (flow rate 1 mL minꢁ1). Polymer
molecular weight data is quoted with respect to polystyrene cali-
brants. For each GPC sample, a single solution was prepared by
accurately adding 10 mL of solvent to an accurately known mass
of ca. 20 mg of sample. The solutions were left for 2 h to dis-
solve/disperse and were then thoroughly mixed before being fil-
Into a three-armed round bottomed flask was charged with lin-
oleic acid (25.00 g, 89.00 mmol) and tris(hydroxymethyl)amino-
methane (THAM) (10.80 g, 89.00 mmol). The flask was purged
with nitrogen and slowly heated to 160 °C with vigorous stirring
under a high flow rate of nitrogen to remove the water formed dur-
ing the reaction. After being stirred for 48 h at 160 °C, the mixture
was cooled down to 80 °C and slowly poured into acetone
(1500 mL) with stirring. The solution was maintained at room tem-
perature and a white solid formed, which was collected by filtra-
tion and recrystallised from acetone to afford 2 as a white
powder (26 g, 80%). M.p.: 60–62 °C; FTIR (KBr, cmꢁ1): 3353 (OH),
3084, 3010 (cis-CH@CHACH2@CH), 2927, 2852, 1656 (oxazoline
ring), 1464 (symmetric COO-stretching), 1428, 1367, 1328, 1270,
1223, 1182, 1140, 1088, 1030, 993, 973, 949, 724, 670. 1H NMR
(250 MHz, CDCl3): d 0.89 (t, J = 7.5 Hz, 3H), 1.31 (br, 14H), 1.60
(m, 2H), 2.06 (m, 4H), 2.28 (t, J = 7.5 Hz, 2H), 2.77, (t, J = 7.5 Hz,
2H), 3.63 (ABq, J = 12.5 Hz, 4H), 4.15 (s, 2H), 5.35 (m, 4H). 13C
NMR (62.5 MHz, CDCl3): d 14.51, 23.00, 26.04, 26.53, 27.61,
27.62, 28.67, 29.53–29.58 (3C), 29.76, 30.03, 31.94, 65.49, 72.16,
76.07, 128.29, 128.49, 130.41, 130.66, 171.24. CI-MS calcd. for
tered through
a 0.2 lm polyamide membrane. Modulated
differential scanning calorimetry (MDSC) measurement was per-
formed on a TA Instruments 2920 MDSC V2.6A. Thermo-gravimet-
ric analysis was carried out on a TA Instruments AutoTGA 2950HR
V5.4A and the samples (5–15 mg) were heated from room temper-
ature up to 600 °C under dry nitrogen gas at a heating rate of 5 °C/
min. MDSC and TGA data were collected and processed on Univer-
sal Thermal Analysis Software.
2.1.1. Viscosities studies
The comb polymers were diluted to 70 wt% solid by addition of
white spirit at room temperature and stirred vigorously for 10 min
in order to give an homogeneous pale yellow oil. These comb poly-
mer solutions were mixed with commercial alkyd resins (a soy oil
based alkyd with 70 wt% in low odour white spirit) at increasing
comb polymer concentrations (from 5 to 50 wt% solid) and these
mixtures were stirred vigorously for 10 min to give homogenous
blends. This procedure ensured that the total solids content re-
mained at 70 wt%. Viscosity data was collected using a cone and
plate viscometer at both 25 °C and 50 °C.
C
22H39NO3 365.2930, found (M+H+) 366.3001.
2.3. Comb polymer synthesis and characterisation
2.3.1. General procedure
Into a three-armed flask was added the calculated amount of
adipic acid 3 and monomer 1 or 2. The flask was purged with nitro-
gen and transferred into an oil bath maintained at 160 °C. After the
mixture was molten it was vigorously stirred under a high flow
rate of nitrogen to remove the water formed during the reaction
for a period of 8 h. After this time 13C NMR and IR spectroscopic
analysis revealed that the resonance of the carboxylic acid group
was not evident (see Supporting Information, Figs. S1 and S2), then
the reaction mixture was submitted to a reduced pressure for
30 min to distil off residual water to yield a pale-yellow viscous oil.
2.1.2. Drying studies
Coating samples for drying studies were prepared by addition of
these three drying agents (Octa-soligen 10, 0.5 wt%; Octa-soligen
calcium 10, 2.0 wt%; Octa-soligen zirconium 18, 2.8 wt%) and
MEKO into the blends and vigorously stirred for 10 min. Each sam-
ple (100
ll) was taken by capillary glass tube and coated on a rect-
angular glass braid substrate (size: 15.700 mm (l) ꢀ 10.000 mm

G. Cheng et al. / Reactive & Functional Polymers 73 (2013) 619–623
621
2.3.2. Comb polymer 4
containing side groups would undergo crosslinking during curing
[31], producing the desired robust paint finish.
This material was synthesized according to Section 2.3.1:- the
molar ratio of adipic acid (2.49 g, 16.9 mmol) and monomer 1
(8.24 g, 22.6 mmol) was 3:4. Yield: 95% (9.60 g); FTIR (KBr,
cmꢁ1): 3277 (OAH), 3002 (olefinic = CAH stretching), 2925, 2853
(CH3/CH2 stretching), 1741 (C@O ester group stretching vibra-
tions), 1661 (oxazoline signal), 1463 (symmetric COO-stretching),
1378, 1242, 1166 (OAC stretching ester), 1061, 1002, 911; 1H
NMR (250 MHz, CDCl3): d 0.88 (t, J = 7.5 Hz), 1.30 (br), 1.66 (m),
2.02 (m), 2.29 (t, J = 7.5 Hz), 3.63 (m), 4.12 (m), 5.35 (m). 13C
NMR (62.5 MHz, CDCl3): d 14.1, 22.5–34.0, 62.6–66.1, 71.4–71.6,
With monomers 1 and 2 in hand, attention turned to the syn-
thesis of the targeted comb-like polymer structures. This was
achieved by the addition of adipic acid (3) to either of the mono-
mers at 160 °C in the bulk to deliver polymers 4, 5 and 6
(Scheme 2). 1H NMR spectroscopic analysis of the three polymers
revealed an intense double doublet at ca. 4.1 ppm characteristic
of the methylene protons between the newly-formed ester resi-
dues and the oxazoline ring, indicative of successful polyesterifica-
tion. In addition there were two low intensity singlet resonances at
4.43 and 5.91 ppm which could not be removed despite repeated
attempts to purify the polymers by precipitation. Oxazolines have
previously been reported to undergo ring opening under acid con-
ditions [32] as would be present at the beginning of the polymer-
isation procedure described here. The low intensity signals at 4.43
and 5.91 ppm were therefore attributed to the presence of an
amide-triester residue within the polyester main chain – high-
lighted in Scheme 2. This assignment was confirmed by synthesis-
ing small molecule analogues of this structural subunit for
spectroscopic comparison (see Supporting Information Fig. S3).
As a consequence of the slow rate of the ring opening reaction
the ratio between the oxazoline unit and ring opened triester
branching unit is approximately 50:1 in the isolated polymers, as
determined by 1H NMR spectroscopy.
Comb polymers 4, 5 and 6 were soluble in a range of organic
solvents including acetone, CHCl3, CH2Cl2, DMF, DMSO, THF and
methanol. Only polymers 4 and 5 were completely soluble in white
spirit, an important consideration for new paint formulation addi-
tives. GPC analysis of polymers 4 and 5 (Table 1) showed that these
were primarily oligomeric in nature species (Mn ꢂ 2 kDa, DP ꢂ 5)
as would be expected from the molar inequivalence used in the
monomer feed ratio. Polymer 6, synthesized from a 1:1 stoichiom-
etry of diol 1 and adipic acid 3 exhibited a higher Mn (ꢂ4500), but
much higher PDI of 11 when compared to a PDI of approximately
2.1 for 4 and 5. This broad polydispersity for what may have been
considered a simple polycondensation reaction indicates the effect
that even low levels of branching can have on molecular weight
distributions.
72.1–74.2,
127.8–130.4,
169.6–173.5.
Tg = ꢁ34 °C.
GPC:
Mw = 5300, PDI = 2.2.
2.3.3. Comb polymer 5
This material was synthesized according to Section 2.3.1:- the
molar ratio of adipic acid (1.65 g, 11.3 mmol) and monomer 2
(5.48 g, 15.0 mmol) was 3:4. Yield: 95% (6.40 g); FTIR (KBr,
cmꢁ1): 3277 (OAH), 3006 (olefinic = CAH stretching), 2926, 2853
(CH3/CH2 stretching), 1740 (C@O ester group stretching vibra-
tions), 1661 (oxazoline signal), 1462 (symmetric COO-stretching),
1378, 1244, 1164 (OAC stretching ester), 1059, 1000, 914. 1H
NMR (250 MHz, CDCl3): d 0.89 (t, J = 7.5 Hz), 1.31 (br), 1.66 (m),
2.06 (m), 2.32 (t, J = 7.5 Hz), 2.77, (t, J = 7.5 Hz), 3.63 (m), 4.15
(m), 5.35 (m). 13C NMR (62.5 MHz, CDCl3): d 14.1, 22.6–34.1,
64.5–66.0, 71.4–71.9, 72.1–74.2, 127.9–130.2, 169.6–173.5. Tg = -
ꢁ24 °C. GPC: Mw = 4400, PDI = 2.0.
2.3.4. Comb polymer 6
This material was synthesized according to Section 2.3.1:- the
molar ratio of adipic acid (3.31 g, 22.6 mmol) and monomer 1
(8.24 g, 22.6 mmol) was 1:1. Yield: 88% (9.40 g); FTIR (KBr,
cmꢁ1): 3373 (OAH), 3002 (olefinic = CAH stretching), 2925, 2853
(CH3/CH2 stretching), 1740 (C@O ester group stretching vibra-
tions), 1663 (amide I and oxazoline signal), 1553 (amide II), 1463
(symmetric COO-stretching), 1380, 1244, 1165 (OAC stretching es-
ter), 1060, 1006, 934. 1H NMR (250 MHz, CDCl3): d 0.88 (t,
J = 7.5 Hz), 1.30 (br), 1.64 (m), 2.02 (m), 2.32 (t, J = 7.5 Hz), 4.12
(m), 5.34 (m). 13C NMR (62.5 MHz, CDCl3): d 14.1, 22.6–34.0,
62.8–66.0, 71.4–71.8, 72.0–72.3, 127.9–130.2, 169.7–173.4. Tg =
ꢁ37 °C. GPC: Mw = 50000, PDI = 11.
With respect to assessing the suitability of these polymers for
coatings applications, all three polymers (4–6) exhibited glass
transition temperature below ꢁ20 °C and high thermal stability
with the onset of weight loss occurring at a minimum of 197 °C.
3. Results and discussion
3.1. Synthesis and characterisation of oxazoline monomers and comb-
type polyesters
3.2. Drying behaviour of comb polymer and commercial alkyd resin
blends
The synthesis of oxazoline monomers 1 and 2 has been de-
scribed previously [29,30], but extensive characterisation data
was not reported. By modification of this method, these monomers
were synthesized by the addition of three equivalents of linoleic or
oleic acid with one equivalent of tris(hydroxymethyl)aminometh-
ane (3:1 M ratio, respectively) in the bulk under nitrogen at
160 °C (Scheme 1). Recrystallisation from acetone produced mono-
mers 1 or 2 as white powders in 63% and 80% yield, respectively. It
was envisaged that the diol component of the monomers would
be used to produce a polyester type polymer, whilst the alkene-
Blends of a commercially available alkyd resin with the diluted
comb polymer 4 or 5 were obtained according to the procedures
described in the experimental section. Based on the molecular
weight characteristics of the comb polyesters in the blends, differ-
ent concentrations were obtained ranging from 10% to 50% (weight
percent, the weight of the comb polymers divided by the total
weight of solid in the blends, gram/gram). A pronounced decrease
of the viscosities of blends both at 25 °C and 50 °C was observed as
shown in Fig. 1. This effect could be attributed to two factors: a dis-
ruption of the entanglement of polymer chains in the systems by
O
HO
R
OH
Monomer1 : R =
Monomer2 : R =
OH
OH
N
O
H2N
HO
OH
R
Scheme 1. Synthesis of oxazoline monomers 1 and 2.

622
G. Cheng et al. / Reactive & Functional Polymers 73 (2013) 619–623
O
O
OH
O
OH
4.43 ppm
O
N
R
O
O
H2C
O
O
O
O
O
O
1
2
or
CH2
O
NH
O
+
O
R
O
N
5.91 ppm
4.1 ppm
Polymer
HO
O
OH
2
98
R
O
3
Component
monomers
Monomer
ratio
3:4
4
5
6
3 1
:
3:2
3:4
1:1
3:1
Scheme 2. Synthesis of comb polymers 4, 5 and 6.
Table 1
Molecular weight, polydispersity and thermal properties of comb polymers (with onset, 50%, 90% decomposition temperature, weight residue at 500 °C and Tg data).
Comb polymer
Mw (Da)
Mn (Da)
PDI
Tg (°C)
Tonset (°C)
T50% (°C)
T90% (°C)
Weight residue at 500 °C (wt%)
4
5
6
5300
4400
50000
2400
2200
4500
2.2
2.0
11
ꢁ34
ꢁ37
ꢁ24
221
197
246
403
400
416
459
457
491
8.8
5.9
8.9
Table 2
Viscosities of comb polymers 4 and 5.
Temperature (°C)
Viscosity of the polymers (poise, cone and plate)
Alkyd
4 (70% solid)
5 (70% solid)
25
50
38.5
5.5
4.0
1.0
2.8
0.8
comb polymers [33] and the large disparity of the viscosities be-
tween the comb-polyester and alkyd resin (Table 2).
The curing performance of the polymers was also investigated
by dynamic mechanical analysis (DMA) over a drying time of
3 days. Conducting the DMA measurements in shearing mode pro-
vides information concerning progress of air drying and any in-
crease in crosslink density [34,35]. Since 1,4-diene groups are the
primary sites for crosslinking of drying oils such as linoleic acid
[31], comb polymer 5 was used for studying of the drying behav-
iour of the blend rather than using 4.
In a comparative study, two organic coating systems were for-
mulated: coating-A (formulated with alkyd resin and driers in
the presence of anti-skinning agent, methyl ethyl ketone oxime
(MEKO)) and coating-B (formulated with blend of alkyd resin with
comb polymer 5 with 5 wt% solid and driers in the presence of
MEKO). These coating systems were submitted to DMA at 30 °C
for a period of 3 days (Fig. 2).
The DMA data reveals that both systems exhibit two distinct
drying stages: physical drying/solvent evaporation within the first
4 h with a slow increase of shear storage modulus (see the inset in
Fig. 2) and after this induction period molecular crosslinking oc-
curred. The physical drying rate of the blend was slightly higher
when compared to commercial alkyd resin, presumably as a conse-
quence of the viscosity-reducing effect of comb polymer 5 in the
blend. Furthermore, after the induction period the blend possessed
an accelerated crosslinking rate in the dry process. Thus, at equal
Fig. 1. Comb polymers 4 and 5 as viscosity-reducing agent in the blends at 25 °C
(upper plot) and 50 °C (lower plot). The viscosity of blend decreased when different
contents of comb polymers were mixed with commercial alkyd resin.

G. Cheng et al. / Reactive & Functional Polymers 73 (2013) 619–623
623
thank Mr. Steve Murray (AkzoNobel Ltd.) for assistance with GPC
analysis.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.reactfunctpolym.
2013.01.008.
References
[1] K.D. Weiss, Prog. Polym. Sci. 22 (1997) 203–245.
[2] J. Lindeboom, Prog. Org. Coat. 34 (1998) 147–151.
[3] http://europa.eu/legislation_summaries/environment/air_pollution.
[4] A. Blencowe, L. Davidson, W. Hayes, Eur. Polym. J. 39 (2003) 1955–1963.
[5] C.R. Yates, W. Hayes, Eur. Polym. J. 40 (2004) 1257–1281.
[6] J.M.J. Fréchet, Science 263 (1994) 1710–1715.
[7] P.N. Metha, Coat. Int. Part B: Coat. Trans. 89 (2006) 333–342.
[8] D.K. Chattopadhyay, K.V.S.N. Raju, Prog. Polym. Sci. 32 (2007) 352–418.
[9] K. Manczyk, P. Szewczyk, Prog. Org. Coat. 44 (2002) 99–109.
[10] G.H. Dekker, Paint India 49 (1999) 117–124.
[11] G. Lin, J.A. Baghdachi, J.L. Massingill, Mater. Sci. Eng. 85 (2001) 135.
[12] V.M. Mannari, Y. Guo, J.L. Massingill, Polym. Prepr. 44 (2003) 97.
[13] E. Malmström, M. Johansson, A. Hult, Macromolecules 28 (1995) 1698–1703.
[14] R.A.T.M. van Benthem, Prog. Org. Coat. 40 (2000) 203–214.
[15] R.A.T.M. van Benthem, N. Meijerink, E. Gelad, C.G. de Koster, D. Muscat, P.E.
Froehling, P.H.M. Hendriks, G.J.A.A. Vermelen, T.J.D. Zwartkruis,
Macromolecules 34 (2001) 3559–3566.
Fig. 2. DMA plots of alkyd resin (coating-A) and blend (coating-A): the shear
storage modulus as a function of time measured on paint films coated on glass braid
(with expanded plots in the first 4 h, left).
drying times the crosslinking density of oxazoline based blends are
higher than that of commercial systems.
4. Conclusions
[16] N. Hadjichristidis, M. Pitsikalis, S. Pispas, H. Iatrou, Chem. Rev. 101 (2001)
3747–3792.
[17] M. Schappacher, A. Deffieux, Macromolecules 33 (2000) 3557–3560.
[18] M. Gauthier, M. Möller, Macromolecules 24 (1991) 4548–4553.
[19] A.R. Kee, M. Gauthier, Macromolecules 32 (1999) 6478–6484.
[20] J. Li, M. Gauthier, Macromolecules 34 (2000) 8918–8924.
[21] D. Tomalia, D. Hedstrand, M.S. Ferritto, Macromolecules 24 (1991) 1435–1438.
[22] M. Gauthier, L. Tichagwa, J.S. Downey, S. Gao, Macromolecules 29 (1996) 519–
527.
[23] M.A. Hempenius, W. Michelberger, M. Möller, Macromolecules 30 (1997)
5602–5605.
[24] C.M. Fernyhough, R.N. Young, D. Poche, A.W. Degroot, F. Bosscher,
Macromolecules 34 (2001) 7034–7041.
[25] W. Radke, A.H.E. Müller, Polym. Prepr. 40 (1999) 144.
[26] V. Barbier, B.A. Buchholz, A.E. Barron, J.-L. Viovy, Electrophoresis 23 (2002)
1441–1449.
[27] V.D. Athawale, R.S. Bailkeri, M. Athawale, Prog. Org. Coat. 42 (2001) 132–141.
[28] R.V. Talroze, E.R. Zubarev, M.A. Rogunova, I.A. Litvinov, N.A. Plate, K. Udipi, R.
Kruse, Polym. Adv. Technol. 7 (1996) 182–186.
Comb polymers compatible with commercial alkyd resins have
been synthesized by bulk co-polymerisation of adipic acid with
monomers 1 or 2. Extensive analysis of the resulting polymers re-
vealed that they were not simple linear comb polymers, but con-
tained low levels of branching as a consequence of ring opening
of the oxazoline-based monomers. Blending the novel comb poly-
mers with alkyd resins led to decreases in the viscosities of the
blends. New coating formulations were prepared from blending
commercial alkyd resins and comb polymer 5 which contained
linoleyl side groups. Dynamic mechanical analysis revealed a typ-
ical drying process consisting of an initial physical drying/solvent
evaporation period followed by chemical crosslinking. The drying
rates of the two stages of the new system were more rapid than
for the commercial alkyd resins.
[29] J.A. Frump, Chem. Rev. 71 (1971) 483–505.
[30] P.F. Tryon, U.S. patent 2,504,9510.
[31] Z.W. Wicks Jr., F.N. Jones, S.P. Pappas, D.A. Wicks, Organic Coatings: Science
and Technology, John Wiley & Sons, Inc., Hoboken, New Jersey, 2007.
[32] P. Chevallier, J.-C. Soutif, J.-C. Brosse, Eur. Polym. J. 34 (1998) 767–778.
[33] H. Magnusson, E. Malmström, A. Hult, Macromolecules 33 (2000) 3099–3104.
[34] T. Frey, K.-H. Grobe-Brinkhaus, U. Röckrath, Prog. Org. Coat. 27 (1996) 59–66.
[35] W. Schlesing, M. Buhk, M. Osterhold, Prog. Org. Coat. 49 (2004) 197–208.
Acknowledgements
The authors would like to thank AkzoNobel Ltd. (SRF SOSEG7)
for supporting this study (a postdoctoral research fellowship to
G.C.) and EPSRC (EP/G026203/1) for a grant supporting BWG. We