聚(N-异丙基丙烯酰胺)/聚丙烯酰胺无机/有机互穿网络水凝胶的制备及表征

通过紫外引发聚合方法制备了无机交联的聚(N-异丙基丙烯酰胺)(PNIPAAm)/有机交联的聚丙烯酰胺(PAAm)互穿网络(IPN)水凝胶.利用FTIR和SEM分别表征了凝胶的化学结构和内部形态;测定了凝胶在高温(50℃)时的退溶胀性能;利用DMA和DSC分别研究了凝胶的储能模量随温度的变化及热相转变行为.研究表明,该IPN凝胶具有温度敏感性;与未互穿的无机交联PNIPAAm凝胶相比,IPN凝胶具有多孔的网络结构和超快的响应速率,如10min内失去90%的水;其储能模量增加了3～4倍,相转变行为变弱,而最低临界溶解温度(LCST)提高了1.4℃.

PREPARATION AND CHARACTERIZATION OF INORGANIC/ORGANIC CROSSLINKING POLY(N-ISOPROPYLACRYLAMIDE)/POLY(ACRYLAMIDE) INTERPENETRATING NETWORK HYDROGELS

Interpenetrating network(IPN)hydrogels composing of poly(N-isopropylacrylamide)(PNIPAAm)using inorganic clay(Laponite XLS)as physically cross-linking agent and polyacrylamide(PAAm)chemically cross-linked by N,N'-methylenebis(acrylamide)(MBAAm),were prepared by ultraviolet irradiation polymerization.The structure of resultant IPN hydrogels was successfully characterized by Fourier transform infrared(FTIR)spectroscopy and scanning electron microscopy(SEM);the water retention at 50℃ was measured gravimetrically;dependence of storage modulus on temperature and phase transition behavior were investigated by dynamic mechanical analysis(DMA)and differential scanning calorimetry(DSC),respectively.The results show that this kind of IPN hydrogels are temperature-sensitive,and,compared with inorganically crosslinking PNIPAAm hydrogels,these IPN hydrogels exhibit enhanced storage modulus and ultrafast response rate,such as losing water of 90% within 10 min because of the porous structure which provides the water-releasing channel;by incorporation of PAAm network,the phase transition of PNIPAAm hydrogels is weakened,but the lower critical solution temperature(LCST)is increased.