Crystallization-Driven Surface Segregation and Surface Structures in Poly(L-lactide)-block-Poly(ethylene glycol) Copolymer Thick Films
作者：Jingjing Yang, Yongri Liang*, and Charles C. Han*
關(guān)鍵字：surface segregation, crystallization, block copolymer thin film
論文來(lái)源：期刊
具體來(lái)源：Langmuir, 2014, 30(1), 394-401
發(fā)表時(shí)間：2014年
In this work, we used poly(L-lactide)-blockpoly(ethylene glycol) (PLLA-b-PEG) copolymer thick films to investigate the effect of crystallization on surface segregation, surface crystal orientation, and morphology by attenuated total reflection Fourier transform infrared spectroscopy (ATRFTIR), reflection optical microscopy (ROM), and twodimensional grazing incident wide-angle X-ray scattering (2D GIWAXS) methods. ATR-FTIR results indicated that the surface fraction of PLLA block increased from 0.48 to 0.79 when Tc,PLLA increased from 70 to 110 °C. Polarized ATRFTIR and 2D GIWAXS results indicated that PLLA crystal lamellae preferentially oriented parallel to the film surface with increasing Tc,PLLA. The surface crystallinity of PLLA was almost independent of Tc,PLLA, while the surface crystallinity of PEG decreased with increasing Tc,PLLA. On the basis of surface crystal orientation and crystallization kinetics, we suggested that the excess of PLLA component at the surface was mainly dominated by a coupling effect of crystallization behavior and surface segregation.