Preparation Of Multi-responsive Intelligent Hydrogel And Its Application In Separation

Multi-responsive intelligent hydrogel materials have been put extensive attention on by the researchers,and they can convert external environmental stimuli(such as temperature,pH,light,magnetic field,electric field and stress etc.)to the trigger signals,which lead up to their physical or chemical changes.Due to the rapid development of national economy,great progresses have been made on the environment responsive intelligent hydrogel materials.In this paper,we design and construct a series of multi-responsive three dimensional composite hydrogels and also do some analysis and characterizations on their performances.The responsive intelligent materials show a potential economic application values in oil/water separation or organic dyes adsorption.The main research contents and conclusions are as follows:(1)The poly(DMAEMA-co-MAA)hydrogel is obtained,which is based on a free radical polymerization with dimethyl amino ethyl methacrylate(DMAEMA)and methylacrylic acid(MAA)as monomers.We explore the reaction mechanism,the equilibrium swelling ratio,contact angle and mechanical property of the gel and the structure,wettability,microstructure of composite gel mesh in our studies.The temperature and pH multi-sensibility of compound gel are proved.Oil-water separation experiment are carried out in a gel separation device with stainless steel mesh as bases and silicone oil/water mixture(30,v/v %)as samples.And our tests show that the separation efficiency is as high as 98%.The meshes maintain the high separation efficiency and repetition utilization after 15 uses when T < 55 oC or pH < 13.(2)The poly(MAA/mPD/GO)hydrogel,poly(CMC/MAA/GO)hydrogel and poly(CMC/MAA/mPD)hydrogel are prapared by a self-assembly method via one-step process with methyl acrylic acid,m-phenylene diamine(mPD),carboxymethyl chitosan(CMC)and graphene oxide(GO)as raw material,respectively.Ultraviolet and fluorescence analyses show that poly(MAA/mPD/GO)hydrogel and poly(CMC/MAA/mPD)hydrogel emit fluorescence at certain intensity in 365 nm UV light because of the MAA/mPD complex copolymer.And the structure,composition,microstructure and mechanical properties of the composite hydrogels have also been characterized by SEM,FT-IR,XPS,TGA and rheological test.(3)Based on above experiments,poly(CMC/MAA/mPD/GO)hydrogel is prepared through self-assembly method with hydrothermal reaction.In addition to the above characterizations,comparisons are made among the three hydrogel about thermal stability and mechanical properties measured by TGA and stress-strain test,respectively.The experimental results show that the poly(CMC/MAA/mPD/GO)hydrogel exhibits optimum thermal stability and 3 Mpa yield stress.At the same time,it shows photoluminescence and pH sensitivity.Simulates adsorption tests are taken out with methylene blue as convenience sample,and the methylene blue solution becomes clarified after reaching adsorption equilibrium.Preparing the same concentration of methylene blue,methyl orange,cresol red,malachite green,methyl violet and Victoria blue solution for adsorption test,we find that poly(CMC/MAA/mPD/GO)hydrogel has the best performance and good cycle stability for methylene dye molecules adsorption at the same conditions.