Interface stabilization and micelle formation in blends with a block copolymer

Abstract

The phase separation behavior of ternary blends of two homopolymers, PMMA and PS, and a block copolymer of styrene and methylmethacrylate, P(S-b-MMA), was studied. The homopolymers were of equal chain length and were kept at equal amounts. Two copolymers were used with blocks of equal length, which exceeded or equaled that of the homopolymer chains. Varied was the copolymer content f. Films were cast from toluene, which is a nonselective solvent. The morphologies of the cast films were compared with the structure of the critical fluctuations in solution, which were calculated in mean field approximation. The axis of blend compositions f can be divided into parts of dominating macrophase and microphase separation. Above a transition concentration fo, all copolymer chains are found in phase interfaces. Below fo, part of them form micelles within the homopolymer phases.

Use of poly(ethylene‐co‐vinyl alcohol) as compatibilizer in LDPE/thermoplastic tapioca starch blends

“…Such a phenomenon has been reported for several blend systems using reactive compatibilizers. It has been argued 15,16 that when the interface becomes "saturated" with the compatibilizer the latter forms micelles or remain trapped in one of the two immiscible phases. For higher TS loadings also, that is, for 40 and 50%, there is very little improvement in the impact strength at high compatibilizer levels beyond 15% (based on TS).…”

Monte Carlo simulations of copolymers at homopolymer interfaces: Interfacial structure as a function of the copolymer density

“…The structure of copolymers at interfaces has been studied intensely in experiments [13,16,[26][27][28][29][30][31][32][33][34][35][36], and theoretically by various refined mean field theories [37][38][39][40][41]. Computer simulations provide a useful way of obtaining additional structural information, and testing theoretical concepts [42].…”

Interfaces between highly incompatible polymers of different stiffness: Monte Carlo simulations and self-consistent field calculations

“…Since the entropy of mixing in polymeric systems decreases with increasing degree of polymerization, a small unfavorable mismatch in enthalpic interactions, entropic packing effects or the combination of both, generally leads to materials which are not homogeneous on mesoscopic scales, but rather fine dispersions of one component in another. Therefore properties of interfaces between unmixed phases are crucial in controlling the application properties of composites [1] and have found abiding experimental interest [2,3,4,5]. Recently, the bulk phase behavior and surface properties [6] of polyolefins [7,8] with varying microstructure has attracted considerable experimental and theoretical interest.…”