Ring‐opening graft polymerization of L ‐lactide onto starch granules in an ionic liquid

A room temperature ionic liquid 1‐allyl‐3‐methylimidazolium chloride ([AMIM]Cl) was a promising direct solvent for starch and nonderivitizing solvent for starch‐effective dissolution, in which the ring‐opening graft polymerization (ROGP) of L‐lactide (L‐LA) onto starch chains was carried out homogeneously. The obtained starch grafted poly(L‐lactide) (starch‐g‐PLLA) was characterized by FTIR, 13C NMR, DSC, and WAXD, and the good adhesion between the two components was evidenced by SEM observations although the chains of grafted PLLA were not long. The grafting efficiency of PLLA reached 30% when the ROGP proceeded at 100°C for 10 h with L‐LA/starch 0.5 : 1 (wt/wt) and stannous octoate (Sn(Oct)2) as a catalyst, which was calculated according to a standard curve newly created by FTIR method. The homopolymerization of L‐LA and the disconnection of grafted PLLA from starch‐g‐PLLA were the main competition reactions.