The Structure Formation Of Polylactide Ion Gel And Its Modulation

Polylactic acid(PLA), also known as poly lactide, is biodegradable polymer materials of polyester family and it is composed of lactic acid molecules by polycondensation. PLA can be made from renewable resources such as corn, potatoes, PLA has a good mechanical performance and can be processed into consumer goods easily, it has became more and more popular in real life. Polylactic acid ion gel is a space mesh structure through interaction by molecular-stress between the complex connection, the gap of mesh structure is full of ionic liquid. Ionic liquid is involatile, it endowed polylactic acid ion gel a good electrochemical performance, at the same time, PLA make ion gel with the biocompatibility, PLA ionic gel combine both electrical and mechanical strength, biological properties, in the field of biological materials and electrochemical intelligent materials have broad application prospects.There are three main topics in this article, respectively expound the formation mechanism of crystal morphology about polylactide ion gel, the physical modification methods of improving polylactide ion gel modulus, and the preparation of polylactide ion gel porous membrane by phase separation, we have a further research in the principle, method and application providing a experimental reference for academic research and production application.(1) In general PLA is not easy to form a band spherulite, however, after blending with ionic liquids it can form band spherulite, by observing the crystal morphology of polylactide ion gel we put forward the factors affecting the formation of ring spherulite, namely disentanglement, the viscosity of amorphous layer and chain entanglement are reduced by ionic liquid, it is advantageous to the wafer turn to form a band spherulite in the mixture. In addition, the formation of band spherulite in the mixture depends on crystallization temperatures and the concentration of ionic liquid, and it is closely related to the change of unbalanced stress about the wafer reverse.(2) Usually ionic conductivity is inversely proportional to the modulus of the gel, when conductivity is high mechanical strength of the gel is often very weak, the general requirements need gel with high conductivity and strong modulus in the application of electrochemical components. Adding nucleating agent to polylactide ion gel can effectively improve the gel modulus and conductivity, the polylactide acid in ionic liquid can form isolated spherical structure, resulting in low modulus of the gel. After adding nucleating agent can significantly improve the nucleation density of PLA crystallization, and constitute a network structure, make the gel modulus increased three orders of magnitude. The size of the conductivity has nothing to do with the addition of nucleating agent, only related to the number of ion migration. We provide a simple and feasible method to increase the modulus of ion gel by studying PLA crystallization.(3) Polylactic acid(PLA) in porous material is often as a phase of be removed, however, its natural biodegradable ability make its porous materials have a significant role in our daily life, therefore developed the polylactic acid nano pore membrane material is still a challenge. We can obtain Polylactide ion gel membrane which crystallized under different temperature by high temperature compression molding, then remove ionic liquids, get polylactic acid(PLA) porous membrane with different structure and size, the research found that content of ionic liquids and the change of the phase separation strength can effectively control the hole’s isolation and connectivity, low temperature is advantageous to the formation pore, high concentration is conducive to form large and connecting holes, but the crystallization temperature too low or the content of ionic liquid too little is not good for double continuous porous membrane formation of polylactic acid. We can get the perfect porous membrane when crystallization temperature is 4℃ and the ionic liquid content is 70wt%, at this time the retention of proteins is higher than anyother can reach more than 96%.