Architecture and solution properties of hyperbranched polymers via the living radical mechanism

Abstract

A novel route to hyperbranched polystyrenes (PSs) from N,N-diethylaminodithiocarbamoylmethylstyrene (DTCS) as an inimer by one-pot photopolymerization is presented. This polymerization proceeded by the self-addition living radical mechanism. Branched PSs were also prepared by living radical copolymerization of DTCS with styrene under UV irradiation. Two monomers (DTCS and styrene) showed equal reactivity towards both propagating species and the copolymer composition was the same as the comonomer composition. Both branching and the chain length of hyperbranched molecules could be controlled statistically by the feed monomer ratios. Hyperbranched poly(ethyl methacrylate)s (PEMAs) were also prepared by the self-addition living radical polymerization of 2-(N,N-diethylaminodithiocarbamoyl)ethyl methacrylate (DTCM). Copolymerizations of DTCS with maleic anhydride (MA) were carried out under UV irradiation. These reactivities showed strong alternation and the propagating copolymer radicals always proceeded with homopolymerization of 1 : 1 complexes formed between the donor and acceptor monomers. These hyperbranched polymers exhibited large amounts of photofunctional carbamate (DC) groups on the peripheral surface. Subsequently, amphiphilic hyperbranched-graft copolymers were derived by grafting from a hyperbranched PS macro-initiator with 1-vinyl-2-pyrrolidinone. These graft-hyperbranched copolymers were soluble in water and methanol. The dilute solution properties of such hyperbranched polymers were studied in detail.

Keywords:

• hyperbranched polymer
• living radical mechanism
• hyperbranched-graft copolymer