Diblock copolymers as emulsifying agents in polymer blends: Influence of molecular weight, architecture, and chemical composition

Cigana, Patrick; Favis, Basil D.; Jérôme, Robert

doi:10.1002/(sici)1099-0488(19960715)34:9<1691::aid-polb18>3.0.co;2-2

Cited by 119 publications

(112 citation statements)

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“…[22,[27][28][29][30][31][32][33] For blends containing LCP, interfacial properties also affect the deformation of in situ-formed fibrils. [27,30] Therefore, observing the morphology evolution, which is greatly affected by interfacial properties, is important to understand the mechanical properties of blends.…”

Section: Sem Morphologiesmentioning

confidence: 99%

Morphologies and mechanical properties of polyarylate/liquid crystalline polymer blends compatibilized by a multifunctional epoxy resin

Chen

Chang³

2000

Macromol. Chem. Phys.

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The tetrafunctional epoxy resin, tetraglycidyl‐4′,4′‐diaminodiphenyl methane (TGDDM), has been investigated as an efficient reactive compatibilizer for the blends of polyarylate (PAr) with a liquid crystalline polymer (LCP). TGDDM can react with PAr and LCP at the interface simultaneously to produce the PAr‐co‐TGDDM‐co‐LCP mixed copolymers during melt blending. These copolymers tend to anchor along the interface as the result of the interfacial reaction and thus serve as effective compatibilizers to reduce the interfacial tension and to enhance the interfacial adhesion in the solid state. The morphologies of the PAr/LCP blends were inspected by means of scanning electron microscopy (SEM). It is observed that the dispersed LCP phase domains reduce obviously after compatibilization. Furthermore, it is also found that the reduced interfacial tension caused by the addition of TGDDM plays a vital role in affecting the deformation of the LCP phase domains in the compatibilized PAr/LCP blends. The LCP phase tends to deform into greater numbers and finer fibrils with high aspect ratio after the addition of TGDDM in those blends containing adequate LCP content (> 10 %). In the blend containing low amount of LCP (Par / LCP = 95/5) with high TGDDM content (0.3 phr or higher), however, the LCP phase can only exist as fine but short fibrils or even ellipsoids. The overall mechanical properties of the PAr/LCP blends are substantially improved after compatibilization by this coupling‐type reactive compatibilizer. The generation of LCP fibrils with high aspect ratio and improved interfacial adhesion are the two hinges to enhance the performance of the compatibilized PAr/LCP blends.

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Section: Sem Morphologiesmentioning

confidence: 99%

Morphologies and mechanical properties of polyarylate/liquid crystalline polymer blends compatibilized by a multifunctional epoxy resin

Chen

Chang³

2000

Macromol. Chem. Phys.

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“…A major driver of interest in such systems is that, by adjusting the length of the tapered region, one can tune microphase behavior and physical properties such as glass transition temperature (T g ) and orderdisorder transition temperature (T ODT ), as has been found in experiments by multiple groups. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] As would be intuitively expected, adding a taper generally increases the miscibility of the system, effectively decreasing the segregation strength (quantified by χN, the Flory χ parameter times polymer length) and widens the interfacial regions of the microphase separated structures. Furthermore, tapering has been shown to change the microphase behavior and dynamics versus typical diblocks in ways that cannot be explained by a simple shift in effective segregation strength.…”

Section: Introductionmentioning

confidence: 99%

Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

Levine

Seo

Brown

et al. 2016

The Journal of Chemical Physics

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Tapered diblock copolymers are similar to typical AB diblock copolymers but have an added transition region between the two blocks which changes gradually in composition from pure A to pure B. This tapered region can be varied from 0% (true diblock) to 100% (gradient copolymer) of the polymer length, and this allows some control over the microphase separated domain spacing and other material properties. We perform molecular dynamics simulations of linearly tapered block copolymers with tapers of various lengths, initialized from fluids density functional theory predictions. To investigate the effect of sequence dispersity, we compare systems composed of identical polymers, whose taper has a fixed sequence that most closely approximates a linear gradient, with sequentially disperse polymers, whose sequences are created statistically to yield the appropriate ensemble average linear gradient. Especially at high segregation strength, we find clear differences in polymer conformations and microstructures between these systems. Importantly, the statistical polymers are able to find more favorable conformations given their sequence, for instance, a statistical polymer with a larger fraction of A than the median will tend towards the A lamellae. The conformations of the statistically different polymers can thus be less stretched, and these systems have higher overall density. Consequently, the lamellae formed by statistical polymers have smaller domain spacing with sharper interfaces. Published by AIP Publishing. [http://dx

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“…Among the copolymers used as compatibilizers, block copolymer is reportedly superior to graft copolymer; moreover, high-molecular-weight diblock copolymers with a balanced composition (symmetrical) exhibit even better compatibilization ability. 10 In addition to the studies of block copolymers as compatibilizers, much recent work has focused on the self-assembling properties of amphiphilic block copolymers for use as emulsifiers in drug delivery systems. 5,8,11 In drug delivery systems, hydrophobic drugs are entrapped in the core of block copolymer micelles.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of cellulose-b-polystyrene

Yagi

Kasuya

Fukuda

2010

Polym J

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A block copolymer of cellulose and polystyrene (PS) was synthesized through atom transfer radical polymerization. Macroinitiators (MIs) were prepared by introducing 2-chloroacetamide to the reducing end of cellulose (degree of polymerization¼20, 50, 250). Subsequently, MIs were copolymerized with styrene monomer in a system of N,N,N ¢,N 00 ,N 00 -pentamethyldiethylenetriamine/CuCl or CuBr/ascorbic acid at 130 1C. The resulting copolymers were characterized by 1 H nuclear magnetic resonance and size-exclusion chromatography. The kinetic study indicated that the polymerization was controllable. The efficacy of copolymers in compatibilizing an immiscible cellulose/PS blend was confirmed by microscopic observation. The mechanism of thermal and thermo-oxidative decomposition of the blend was investigated by thermogravimetry.

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Diblock copolymers as emulsifying agents in polymer blends: Influence of molecular weight, architecture, and chemical composition

Cited by 119 publications

References 1 publication

Morphologies and mechanical properties of polyarylate/liquid crystalline polymer blends compatibilized by a multifunctional epoxy resin

Morphologies and mechanical properties of polyarylate/liquid crystalline polymer blends compatibilized by a multifunctional epoxy resin

Effect of sequence dispersity on morphology of tapered diblock copolymers from molecular dynamics simulations

Synthesis and characterization of cellulose-b-polystyrene

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