Depletion Interactions: Effects of Added Homopolymer on Ordered Phases Formed by Spherical Block Copolymer Micelles

被引：17

作者：

Abbas, Sayeed ^{[1
]}

Lodge, Timothy P. ^{[1
,2
]}

机构：

[1] Univ Minnesota, Dept Chem Engn & Mat Sci, Minneapolis, MN 55455 USA

[2] Univ Minnesota, Dept Chem, Minneapolis, MN 55455 USA

来源：

MACROMOLECULES | 2008年 / 41卷 / 22期

基金：

美国国家科学基金会;

关键词：

D O I：

10.1021/ma8013838

中图分类号：

O63 [高分子化学（高聚物）];

学科分类号：

070305 ; 080501 ; 081704 ;

摘要：

Three distinct poly(styrene-b-isoprene) (SI) diblock copolymers with molecular weights of 16-16, 38-14, and 50-13 kDa for styrene and isoprene, respectively, formed spherical micelles when dissolved in diethyl phthalate (DEP). Since DEP is a styrene-selective solvent, micelles with polyisoprene in the core and polystyrene in the corona were formed. At block copolymer concentrations of 20%, 16%, and 14% in DEP, the spherical micelles of SI(16-16), SI(38-14), and SI(50-13) pack onto a face-centered cubic (FCC) lattice, a mixture of FCC and body-centered cubic (BCC) lattices, and a BCC lattice, respectively. Polystyrene homopolymers with molecular weights of 4, 48, and 180 kDa were added to these ordered solutions. The following general trends were observed: the FCC phase tended to disorder, and samples that originally behaved like soft solids exhibited liquidlike flow behavior. The effect increased strongly with both the molecular weight and concentration of homopolymer in the solution. Furthermore, the BCC lattice tended to be displaced by the FCC lattice, or to disorder, when homopolymer was added. These results can be explained by invoking depletion interactions, which have been studied extensively in colloid/polymer mixtures. However, the phenomenon differs in certain details from colloidal systems because the addition of homopolymer can

引用

页码：8895 / 8902

页数：8

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