Synthesis of novel amphiphilic graft copolymers composed of poly(ethylene oxide) as backbone and polylactide as side chains

A well-defined amphiphilic comb-like copolymer of poly(ethylene oxide)(PEO) as main chain and polylactide (PLA) as side chain was successfully prepared via a combination of anionic polymerization and coordination-insertion ring-opening polymerization. The anionic copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out using potassium 2-(2-methoxyethoxy)ethoxide as initiator, and then ethoxyethyl groups of EEGE units of the copolymers obtained were removed by hydrolysis. Two copolymers of methoxypoly(ethylene oxide-co-glycidol) [mpoly(EO-co-Gly)] were formed with multiple hydroxyl sites (the molar ratio values of Gly to EO in copolymers: 1/10.6 and 1/5.2; Mn: 10,100 and 5,020 respectively), and them were used further to initiate the ring-opening polymerization of lactide in the presence of stannous octoate, and a well-defined comb-like copolymer of PEO as main chain and PLA as side chain was obtained. The intermediate and final products of PEO-g-PLA were characterized by GPC and NMR in detail.