New routes to hyperbranched poly(acrylic acid) surface grafts on polyethylene films and powders

Hyperbranched grafting is a useful method for surface modification of both inorganic and organic polymer surfaces but is synthetically cumbersome as it requires synthesis of functional polymers as reagents. This paper describes an alternative approach using acrylic acid and Ce(IV) graft-on-a-graft chemistry. The substrates, polyethylene films and powders, were prepared for grafting by oxidation and incorporation of a low loading of a polyhydroxylated oligomer. In subsequent steps, the hydroxyl groups of this surface are successively grafted with Ce(IV) and acrylic acid. The resulting carboxylic acid groups were converted into yet more hydroxyl groups. Repetition of this process yields a hyperbranched graft. Copolymer grafts too can be prepared using appropriate mixtures of monomers.