Preparation And Characterization Of PMMA Based Thermal-stimuli Multi-responsive Solid Materials

The temperature responsive polymer is a kind of materials that under external temperature stimulation changed its physical structure and chemical properties.And among them the water-soluble polymer is a kind of temperature response polymers that researched more.In the stimuli process of this kind of materials,the phase transition with large volume shrinkage occurs,which has been widely used in the fields of drug release and genetic engineering,but it is difficult to be apply to the solid state devices.The volume shrinkage of solid materials in the response process is small,but the free volume needed to create the response here is a big challenge of polymer network,adding a low glass transition temperature?T_g?component in the polymer could offer a high free volume to the polymer.Firstly,a new type of temperature responsive solid materials?TRSMs?was obtained by adding certain solvents into the process of MMA's bulk polymerization.In order to explore which kind of solvents that meet the requirements of preparation of the TRSMs,this paper based on the solubility parameter???of the PMMA and selected part of the solvents with?in a certain range of 19³0 MPa¹/2/2 to conduct experiments.When diethyl carbonat,vinyl acetate,1,4-dioxane were copolymerized into MMA prepolymer system and allowed to coalesce to form solid materials which were transparent at room temperature.When diethylene glycol was copolymerized into,the solid material was non-transparent even at high temperature.When isopropyl alcohol?IPA?,butyl alcohol?nBA?,isobutyl alcohol?IBA?,cyclohexanol?CYH?,hexanol?HA?,octanol?CA?,diethylene glycol monohexyl ether?DEGHE?,2-Ethyl Hexyl Di Glycol?EHDG?was dispersed into performed polymer of MMA,a new type of solid materials was found.With the increase of temperature,the phase transition from opaque to transparent was appeared.Among these solvents only IPA,nBA,IBA,CYH,HA,CA,DEGHE,EHDG meet the requirements of preparation of TRSMs,these solvents had stronger hydrogen bonds,the difference between them and PMMA is 1 to 5 MPa^1/2.The consumption of the solvents to preparation TRSMs was investigated,it was found that only in the range of proper amount can get the responsive property of solid materials obviously,and the solvent whose compatibility to PMMA was better needed larger quantity of solvent to get the response of the materials.The results shows that the better the compatibility of the system,the lower the boiling point of the solvent,the stronger the hydrogen bond,the less amount of solvent,the lower the phase transition temperature of the system.In addition,the TRSMs also had the properties of shape memory response and self-repairing.Secondly,we prepared multi-responsive solid materials by doping ionic liquid—1-butyl-3-methylimidazolium trifluoromethanesulfonate into solid materials.Under thermal stimulus,it had multiple responses,such as light and electrochemistry.With the increase of the content of ionic liquid in a certain range,the phase transition temperature of the system decreases,the conductivity increases,but the conductivity change rate decreases gradually.Finally,the PMMA/IPA system was further studied,it was found that the cycle stability of PMMA/IPA was limited,so the material is not conducive to long-term repeated use and preservation.We think that it may be due to the volatilization of the low boiling point solvent.In order to look for materials with long service life,we use high boiling point solvent DEGHE and EHDG instead of IPA to improve the stability of the materials and found them did effectively improve the stability of the materials.