Effect of 1,2,3-triazolium-functionalized PEG-b-PCL block copolymer on crystallization behavior of poly(L‑lactic acid) as nucleation agent and mobility promoter

The effect of 1,2,3-triazolium-functionalized PCL-b-PEG block copolymer (PCL-b-PEG(IL)) on crystallization behavior and kinetics of PLA was systematically studied by DSC, POM and XRD. A small amount of micelle of aggregated PCL-b-PEG(IL) containing ionic clusters and a large number of disaggregated PCL-b-PEG(IL) can significantly improve the chain segment mobility of PLA. The glass transition temperature and cold crystallization temperature of PLA gradually decreased with the increase in PCL-b-PEG(IL) or PCL-b-PEG content. Compared with PCL-b-PEG, PCL-b-PEG(IL) decreases the Tg of PLA more obviously because of the strong plasticizing effect of PCL-b-PEG(IL). More importantly, the isothermal crystallization kinetics results manifested that the synergistic effect of heterogeneous nucleation agent of ionic clusters of PCL-b-PEG(IL) and chain mobility promoter of PEG chain segment can enhance the crystallization ability of PLA at all crystallization temperature. The 5 mass% PCL-b-PEG(IL) can induce high amount of stable ??-form crystal of PLA after annealing treatment.