Preparation Of Photo-thermal Graded Response Shape Memory Liquid Crystal Polyurethane

Thermal shape memory polyurethane(TSMPs)has attracted more and more attention because of a broad adjustable transition temperature,large deformation,active and convenient shape change in response to external condition.However,common TSMPs cannot realize the remote control in the application of block system.Since light is an environment-friendly,remotely controllable and instantly operatable stimulus,photoresponsive polymers attract more and more attention.Therefore,the research was carried out in this study to better combine the thermal shape memory properties and photoresponsive polymers characteristics.Thus,materials with more functionalities are developed.Firstly,the structures and properties of the Polycaprolactone liquid crystal polyurethane shape memory material(PASMPU)were investigated.The results indicated that PASMPU have micro phase separation and separation structure,good thermal qualitative and excellent liquid crystallinity.Meanwhile the crystallizability of hard segment increases with the increase of Azoba content.Uv Absorption spectrophotometric and thermal analysis are used to study the conflict properties of shape memory performance,the results showed PASMPU solution can achieve the light response,but the PASMPU film cannot achieve this proposites.The light response of PASMPU need further improved.Secondly,the structures and properties of the N-Methyldiethanolamine liquid crystal polyurethane shape memory material(PMSMPU)were investigated.The results indicated that the crystallization ability of PMSMPU are enhanced with the increases of Azoba content.The thermal analysis showed the PMSMPU have a good thermal stability.DMA results showed that the PMSMPU has good triple shape memory performance.Uv test results showed that PMSMPU has good light responsive,PMSMPU film under UV light can achieve rotating and bending in a very short period of time,then under the action of heat it can be recoveried quickly.The response rates above 95%.Finally,PSMPU is served as the substrate material shape memory polyurethane liquid crystal conposites were prepared by incorporating Azo11 into PSMPU with solution blending method.On the analysis,the results showed that the compound has PSMPU and Azo11 two-phase states of aggregation structure,with the increasing of Azo11 content,PSMPU gradually from the brittle fracture to ductile fracture.Meanwhile,the crystallization ability of soft segment is enhanced with the increase of Azo11 content.DMA test showed that PSMPU-Azo11 composites perform triple shape memory properties,and the Azo liquid crystal at high temperature can promote polyurethane stretching,at low temperature can promote its fixed shape.Uv test results showed that the composites membrane has good light response under the action of ultraviolet light.