Graft copolymers, wettability

The effects of improved wettability, entropic repulsion, and sterical hindrance undoubtedly play a role in stabilizing dispersed solid particles by block or graft copolymers. However, since the dispersions of titanium dioxide in toluene stabilized by carboxylated styrene-butadiene block copolymers are so much more stable than dispersions stabilized by carboxylated homopolymers under otherwise identical conditions, we must assume that an additional factor comes into play when block copolymers are used. The model in Figure 1 is an attempt to explain this additional... 

Mayes group demonstrated the direct preparation of amphiphilic graft copolymers by ATRP of poly(oxyethylene methacrylate) (POEM) monomers initiated from the secondary fluoride sites of PVDF backbone. Surface segregation of PVDF-g-POEM additives in PVDF was examined as a route to wettable and foul-resistant surfaces of PVDF microporous membranes [100-102], ATRP of St, PEGMA, NaSS, 2-(A,A-dimethylamino)ethyl methacrylate (DMAEMA), butyl methacrylate (BMA), and 2VP, initiated directly from the vinylidene fluoride (VDE) units of PVDF main chains, has also been reported [103-109]. 

This principle is applied not only to the PVA-PVAc composites but to other polymer composites. The composite structure does not always need to be porous but may be powders and gels designed for the wettability by solvents and the extension of the surface area in soluble polymers. From this point-of-view, the present work sheds a new light on the research on composite materials related to graft polymers and copolymers. 

Another method to modify PHA is by graft copolymerization, which results in the formation of a modified segmented copolymer with improved properties such as increased wettability and thermo-mechanical strengths. 

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