Living free radical polymerization of cyclodextrin host-guest complexes of styrene via the reversible addition fragmentation chain transfer (RAFT) process in aqueous solution

摘要

Host-guest complexes of styrene and randomly methylated beta-cyclodextrin (m-beta-CD) were polymerized in aqueous medium via the reversible addition fragmentation chain transfer (RAFF) process. 3-Benzylsulfanylthiocarbonylsulfanylpropionic acid (TTC) was used as trithiocarbonate-type RAFT agent. The results indicate a controlled character of the polymerization of the styrene complexes as the number-average molecular weight, (M) over bar (n), increases linearly with monomer to polymer conversion; however, the molecular weights of the obtained polystyrenes deviate to higher values than those theoretically predicted. Nevertheless, the molecular weights can be controlled by variation of the initial RAFT agent concentration. The polystyrenes produced in this system exhibited narrower polydispersities (1.23 < <(M)over bar>(w)/(M) over bar (n)< 2.36) than those produced without RAFT agent (5.24 < <(M)over bar>(w)/(M) over bar (n) < 9.21) under similar conditions. The present contribution represents the first example of RAFT polymerization of a m-beta-CD-complexed hydrophobic vinyl-monomer (styrene) from homogenous aqueous solution.