The Micellization of Well-Defined Single Graft Copolymers in Block Copolymer/Homopolymer Blends

A series of well-defined (polyisoprene)2(polystyrene), I2S, single graft copolymers with similar total molecular weights but different compositions, fPS, were blended with a low molecular weight polyisoprene homopolymer matrix at a constant concentration 2 wt%, and the micellar characteristics were studied by small-angle x-ray scattering. To investigate the effect of macromolecular architecture on the formation and characteristics of micelles, the results on the single graft copolymers were compared with those of the corresponding linear polystyrene-b-polyisoprene diblock copolymers, SI. The comparison reveals that the polystyrene core chains are more stretched in the case of graft copolymer micelles. Stretching turned out to be purely a result of the architecture due to the second polyisoprene block in the corona. The micellization of a (polystyrene)2(polyisoprene), S2I, graft copolymer was also studied, and the comparison with the results of the corresponding I2S and SI copolymers emphasizes the need for a critical core volume rather than a critical length of the core-forming block, in order to have stable micelles. Finally, the absence of micellization in the case of the I2S copolymer with the highest polystyrene volume fraction is discussed. For this sample, macrophase separation occurs, with polyisoprene cylinders formed in the copolymer-rich domains of the phase-separated blends.

Phase behavior in thin films of weakly segregated block copolymer/homopolymer blends

For P(S-b-MMA)/PS mixtures with ϕPS = 64%, PL exists in thin films annealed at 230–270 °C. For thick films, thermal annealing at 245–270 °C produces both PL and DG of various fractions. PL becomes the only discernible phase in thick films annealed at 230 °C.

Interfacially compatibilized PI/PDMS blends with reduced octadecylamine-functionalized graphene oxide: morphological and rheological properties

Interfacial compatibilization effect of reduced octadecylamine-functionalized graphene oxide on the morphological and rheological properties of immiscible homopolymer blends.