溶剂蒸汽诱导非晶左旋聚乳酸薄膜结晶的原位光谱研究

In-situ Spectra Studies on Structure Evolution of PLLA Induced by Solvent Vapor

利用时间分辨的傅里叶变换红外光谱(FT-IR),结合自制实验附件,对室温溶剂诱导左旋聚乳酸(PLLA)薄膜结晶过程中的结构变化进行原位光谱研究,从分子水平上揭示PLLA从无序到有序的结构演变。结果表明:多种溶剂诱导PLLA结晶均形成α′晶型。温度升高时,结晶速率加快,结晶活化能为Ea≈146.1×103 J.(mol.K)-1。除甲苯外,多数溶剂诱导均能诱导PLLA结晶,但其诱导结晶能力不同,其中丙酮可以最有效地加速PLLA结晶。计算所得PLLA的红外结晶度大小顺序为氯仿>丙酮>四氢呋喃>乙酸乙酯>乙醇>甲苯。结晶度较大者对应溶剂的溶度参数与PLLA的溶度参数相近。

Time-resolved measurement of FT-IR has been performed to trace in-situ the structure evolution of PLLA induced by solvent vapor with the self-made experimental accessory at room temperature, revealing the structural changes of PLLA from amor- phous to semi-crystallization on the molecular level. The results showed that PLLA formed ar morphology induced by various solventsr vapor. With the temperature increa- ses, crystallization rate was accelerated, and the activation energy Ea for PLLA crystal- lization wa146.1×10^3J·（moJ·K）^-1. And most of the solvents induced the crystalliza- tion of PLLA film except toluene, while acetone is the most effective solvent to acceler- ate the crystallization among the solvents used. However, the order of crystallinity is chloroform〉acetone〉THF〉ethyl acetate〉alcohol〉toluene. The closer solubility pa- rameter between solvent and PLLA, the higher crystallinity.