| 초록 |
Stable polyurethane-polystyrene (PU-PS) copolymer emulsions were prepared by the polymerization of HEA end-capped PU and styrene, using azobis(isobutyronitrile) (AIBN), a radical initiator, and 4-thiobenzoyl sulfanylmethylbenzoic acid, a reversible addition-fragmentation chain transfer (RAFT) agent. As the molar ratio of the RAFT agent to AIBN increased, the average size and size distribution of the emulsion droplets decreased. The tensile strength, hardness and water-resistance of the films, prepared from the PU-PS copolymer emulsions, were much greater than those of the films prepared from the pure PU emulsion. The copolymer emulsions, prepared via the RAFT polymerization process, are expected to exhibit better storage stability than those prepared via the conventional free radical polymerization process, due to the presence of carboxyl groups derived from the RAFT agent at the PS block termini. |
