Synergetic effects of PEG arm and ionic liquid moiety contained in the tri-arm star-shaped oligomer on the crystallization behaviors of poly(lactic acid)

A tri-arm star-shaped oligomer with PEG arm and imidazolium-based ionic liquid moiety (TSIL) was introduced in poly(lactic acid) (PLA) blends, and the synergetic effects of PEG arm and IL moiety contained in the TSIL on the crystallization behaviors of PLA were investigated by DSC and POM. The results determined by DSC show that TSIL inhibits the crystallization of PLA when the mass content of TSIL in blend is as low as 1 mass%, while the crystallization process is accelerated greatly with increasing mass content of TSIL. As revealed by POM observations, the spherulitic morphology remains unchanged in TSIL/PLA blends and the nucleation and growth of spherulites are altered due to the different effects of PEG arm and IL moiety. The nucleation process is suppressed by IL moiety, while the growth rate of spherulites is improved because of the plasticizing effect of PEG arm. The synergistic effects of PEG arm and IL moiety contained in the TSIL also contribute to the acceleration of kinetics in non-isothermal crystallization process.