Synthesis of Inorganic Silica Grafted Three-arm PLLA and Their Behaviors for PLA Matrix

作     者：Da-Wei Shi Xiang-Ling Lai Yuan-Ping Jiang Cong Yan Zheng-Ying Liu Wei Yang Ming-Bo Yang Da-Wei Shi;Xiang-Ling Lai;Yuan-Ping Jiang;Cong Yan;Zheng-Ying Liu;Wei Yang;Ming-Bo Yang

作者机构：State Key Laboratory of Polymer Materials Engineering College of Polymer Science and Engineering Sichuan University 

出 版 物：《Chinese Journal of Polymer Science》 (高分子科学（英文版）)

年 卷 期：2019年第37卷第3期

页      面：216-226页

核心收录：

学科分类：07[理学] 0703[理学-化学] 

基　　金：financial support of the National Natural Science Foundation of China(Nos.51721091 21674069 and 21174092) 

主　　题：Poly(lactic acid) Nanocomposites Surface grafting Topology Crystallization 

摘      要：The low melt strength and poor crystallization behavior severely limit the processing and application of poly(lactic acid)(PLA) as biodegradable film materials. In this work, three-arm poly(L-lactic acid)(3A-PLLA) grafted silica nanoparticles with two kinds of topology structures were introduced into PLA matrix to improve the biodegradation performance. Different methods were used to characterize the structure of the grafted 3A-PLLA chains, the grafting density, and the thermal decomposition behavior of the nanoparticles. By varying the mass ratios of raw materials and altering the order of dropping solution in the reaction, high grafting densitytangled 3A-PLLA grafted SiO_2 was synthesized as 3A-PLLA grafting to SiO_2(GTS), while low grafting density-stretched 3A-PLLA grafted SiO_2 was obtained as SiO_2 grafting to 3A-PLLA(GTA). Topology of nanoparticles as well as the filler-matrix interaction is critically important to structure bio-nanocomposites with desirable properties. Thus, the GTS and GTA nanoparticles were introduced into PLA matrix to assess the effect. The SEM images showed the uniform dispersion of the modified nanoparticles, while the shear rheology results revealed that GTA nanoparticles made a more significant contribution on the melt-strengthening and relaxation time-extension of PLA. Moreover, it is suggested that GTA nanoparticles were more effective to act as a nucleating agent for PLA, which was proved by differential scanning calorimetry(DSC) and polarized optical microscopy(POM) researches. All of the improvements mentioned above of GTA nanocomposites can be ascribed to stronger entanglements between 3A-PLLA stretched by nano-SiO_2 and PLA matrix.