Effect of POSS-NH2-grafted different plasticizers on the crystallization properties of SC-Poly (l-lactic acid)

Poly (l-lactic acid) (PLLA) and polycarbonate (PCL) grafted Monoamino-Polyhedral oligomeric silsesquioxane (POSS-NH2) (POSS-PLLA and POSS-PCL) by ring-opening polymerization of L-lactide (L-LA) and caprolactone (epsilon-CL) from POSS-NH2 were obtained in this work. The fourier transform infrared spectrometer (FTIR) results show that the stretching vibration peaks of -C(O)-NH- of POSS-PLLA and POSS-PCL appears at 1650 cm(-1) and 1645 cm(-1). The crystal diffraction peaks of POSS-PLLA at 22 degrees, 16.7 degrees and 19 degrees are same as the peak positions of PLLA; POSS-PCL at 21.7 degrees 23.7 degrees are same as the peak positions of PCL by X-Ray diffraction (XRD). Both FTIR and XRD results indicate that the grafted products are synthesized successfully. Then, the different contents of POSS-PLLA, POSS-PCL and purchased POSS-polyethylene glycol (POSS-PEG) were blended with PLLA/Poly (d-lactic acid) (PDLA) (with the mass ratio of 1:1) to prepare ternary blends with different contents of polymer grafted POSS. The effects of POSS-PLLA, POSS-PCL and POSS-PEG on the crystallization behavior of PLLA/PDLA were investigated. The results show that compared with POSS-PCL and POSS-PLLA, POSS-PEG enhances the crystallization ability of PLLA/PDLA, and promotes the formation of stereocomplex (SC); on the contrary, POSS-PCL and POSS-PLLA inhibit the formation of SC.