聚乙二醇末端基對聚乳酸多晶相的結晶動力學的影響

Abstract

本研究主要探討不同末端基的聚乙二醇(PEG)對聚乳酸(PLLA)/PEG系統之相容性及結晶動力學的影響。聚乳酸在結晶時，會在較高的結晶溫度下形成排列較緊密的α晶體結構；在較低的結晶溫度下，形成排列相對較鬆散的α’晶體結構；而在這之間的溫度下，則形成兩相共存的晶體結構。我們將PEG摻入PLLA中，改變玻璃轉移溫度及平衡熔點，利用POM、DSC、XRD觀察其結晶動力學的模式與熱力學參數間的關係，尤其著重在兩相共存區的影響，最後我們也發現這共存區的結構是由兩相透過動力學模式互相競爭而形成。

另外，我們也摻入了PEG-2NH2、PEG-2OH、PEG-2CH3三種不同末端基的PEG，對PLLA/PEG系統進行觀察。不同末端基的PEG與PLLA具有不同的相互作用力，除了改變玻璃轉移溫度及平衡熔點外，也改變了結晶時晶片的摺疊鏈端表面自由能，因此間接影響到PLLA/PEG系統的結晶動力學。

This study focused on the misbility and crystallization kinerics which effected by different end groups of polyethylene glycol (PEG) to poly lactic acid (PLLA) / PEG system. PLLA has ordered α structure which is close at higher crystallization temperature, and relatively loosely in α ' structure at low crystallization temperature. PLLA in PEG incorporation we will change the thermodynamics of the glass transition temperature and equilibrium melting point, using POM, DSC, XRD to observe the relationship between crystallization kinetics model and thermodynamic parameters, especially emphasis on the bouble structure coexistence phase. We also found that the structure is a crystallization kinetic model of two competing growth. In addition, PLLA were also blended with PEG-2NH2, PEG-2OH, PEG-2CH3, three different end groups of PEG to observe the PLLA / PEG system. Different end groups of PEG and PLLA have different misbility, in addition to changing the glass transition temperature and equilibrium melting point, but also changes the crystallization of the surface free energy of chain folding, thus indirectly affecting the crystallization kinetics of PLLA / PEG system.