Graft copolymer of PVAc-g-PIB by cationic polymerization

The cationic grafting polymerization of isobutylene (IB) from a poly(vinyl acetate) (PVAc) backbone was initiated by the combination of PVAc with titanium tetrachloride (TiCl 4 ) in methylene chloride (CH 2 Cl 2 ) solution at -65°C. A mixture of IB homopolymer and PVAc grafted with approximately 9.5% (mol) PIB copolymer was formed. 1 H- and 13 C-NMR spectra confirmed that IB was successfully grafted from the PVAc backbone. PVAc exhibits both initiation and modification behavior. PVAc acts as a macro-initiator in the polymerization to form the graft copolymer. It also plays a role in the homopolymerization of IB initiated by the combination of residual water with TiCl 4 and the product PIB with a narrow molecular weight distribution.