Preparation of amphiphilic graft copolymer with polyisoprene backbone by combination of anionic polymerization and “click” reaction

A novel graft copolymer consisting of polyisoprene backbone and hydrophilic side chain with carbamic acid ester functional group was prepared via thiol-ene “click” reaction and alcohol-isocyanate reactions. Polyisoprene was synthesized by anionic polymerization using n-butyl lithium as initiator, and the pendant hydroxyl groups were introduced by the thiol-ene reaction of mercaptoethanol with the double bond of 1, 2-addition units of PI backbone in the presence of radical initiator azobisisobutyronitrile. Isocyanate end group capped poly(ethylene glycol) (mPEG-NCO) was grafted onto the PI backbone through alcohol-isocyanate reaction between the pendant hydroxyl groups and isocyanate group of mPEG-NCO. The structure of the graft copolymer were characterized and confirmed by means of size-exclusion chromatography, 1H NMR and FTIR spectroscopy.