Preparation And Properties Study Of The Temperature-sensitive Composite Materials Based On N-isopropylacrylamide-acrylate Copolymer

Temperature-sensitive polymer is a kind of attractive intelligent materials.The polymer exhibits good solubility in aqueous solutions at low temperatures but separate from solution when the temperature is raised above the lower critical solution temperature(LCST).As a result of this characteristic,the temperature-sensitive polymer has an excellent application prospect in the field of shading material, temperature control,interior decoration,membrane seperatation and drug delivery.Poly N-isopropylacrylamide(PNIPA) is one of the most studied themperature-sensitive polymers.In this paper,A series of linear copolymers poly(NIPA-co-methyl methacrylate),poly(NIPA-co-ethyl methacrylate),poly(NIPA-co-butyl methacrylate),poly(NIPA-co-ethyl acrylate) and poly(NIPA-co- butyl acrylate)with different mol ratio and average molecular weight were synthesized by solution free radical polymerization in solution.The structures of these copolymers were characterized by ~1H NMR,FT-IR and DSC-TG analysis.The results showed that different ratio of comonomer influence the temperature sensitive properties significantly,in which the range of LCST can be regulated from 18 to 32℃based on the mol ratio of comonomer.The aqueous solution of copolymers change from transparent to opaque when the temperature is above LCST.This change was reversible and exhibited celerity,marked sensitivity and good reproducibility.The reversible changes can be completed within 2～3 minutes and recycle more than 1000 times.Cellulose derivatives were used to composite with the aqueous solution of the copolymer for making thermo-sensitive adhesive liquid.The LCST of the composite material increased about 1℃than the aqueous solution.The reversible change of transparent to opaque still exhibited celerity and can recycle more than 1000 times.Polyvinyl alcohol was also used to composite with the aqueous solution of the copolymer for making thermo-sensitive composite hydrogel.The transmittance of hydrogel with polyvinyl alcohol as the matrix is more than 90%and the LCST of thermo-sensitive composite hydrogel can be regulated from 19 to 33℃.The reversible change of transparent to opaque can be completed in 3～6 minutes and recycle more than 3000 times.The composite hrdrogel exhibits excellent thermo-sensitive properties and is expected to become a good intelligent light-control material that can be applied in the field of smart window for sunshade and heat insulation.