Syntheses and Properties of Block Copolymers Having Poly (vinyl alcohol) as One Component

Redox reaction between the thiol group at one end of poly (vinyl alcohol) (PVA) and potassium bromate initiated polymerization of several monomers in water, yielding block copolymers having the roly (vinyl alcohol) as one component. The block copolymers thus obtained showed behavior obviously different from the blend systems of PVA and corresponding homopolymers. The nature of block copolymer of PVA and polyacrylamide (PAAm) was studied in detail. The block copolymer show slow phase separation in aqueous solution and gave transparent films compared with the homopolymer blend that did not give films due to fast phase separation. Although PVA is not compatible with starch, the block copolymer of PVA with PAAm that is compatible with starch showed considerable improvement in compatibility with starch. The blend of starch with the block copolymer gave more transparent and tougher films than the blend of starch with PVA.