Studies On Thermochromic Smart Hydrogels Base On DMAEMA

In this paper, the novel passive and active thermochromic hydrogels, which can be used as fireproof materials, were made utilizing the property of N,N-dimethylaminoethyl mecrylate(DMAEMA) and PDMAEMA aqueous solution with a lower critical solution temperature(LCST).The copolymer gels of DMAEMA and AA (DMAEMA-co-AA gels) were first synthesized in aqueous medium by radical copolymerization in the presence of K2S2O8 as the initiator, MBAA as cross-linker. Then the thermochromic passive gels were made by using DMAEMA-co-AA xerogels as the container of DMAEMA aqueous solution. A kind of semi interpenetrating network (IPN) hydrogel-poly(DMAEMA-sipn-AA) was also studied as a container to get another kind of thermochromic gel.By using 721-spectrophotometer, Abbe refractometer, DSC and DMA etc., the properties of both DMAEMA-co-AA and DMAEMA-sipn-AA gels such as swelling ratio by water, volume changes with temperature, pH inside the gels, swelling ratio by DMAEMA aqueous solution, ion-sensitivity, dynamic mechanical property and so on were investigated. The optimum conditions of manufacturing such gels were found. It was also found that both the two kinds of container-gels have a good volume stability. Of the two the DMAEMA-sipn-AA gels have a better dynamic mechanical property and a higher responsive temperature, but the DMAEMA-co-AA gels have a better transparence and no ion-sensitivity. Otherwise it was found that the LCST of passive gels can be adjusted by varying the concentration of DMAEMA aqueous solution. All these properties make passive thermochromic hydrogels more suitable as a kind of fireproof materials.A further study on preparation and properties of active thermochromic gels made by DMAEMA were also carried out.