溶致液晶作模板水凝胶的制备及其表征

以表面活性剂Brij 58溶致液晶(LLC)为模板, 采用光聚合的方法合成了结构规整的新型溶致液晶型聚丙烯酰胺(PAAm)水凝胶, 并对其结构、形貌和性能进行了研究. 扫描电镜结果表明活性剂Brij 58用量为10%～40%时, 可形成结构规整、孔径均一的LLC型水凝胶, 其孔径为1～2 µm, 约为普通水凝胶的1/40. 当Brij 58浓度大于50%时, 体系发生相分离, 此时合成的水凝胶含水量及孔隙率下降. 傅立叶变换红外光谱(FTIR)显示, LLC型水凝胶中羰基和氨基的红外吸收向低波数方向移动, 表明其中形成了大量的分子间氢键. 同时, LLC型PAAm水凝胶还保持了普通水凝胶的pH敏感性, 相同条件下, 其溶胀比大于普通水凝胶.

Preparation and Characterization of Hydrogels with Lyotropic Liquid Crystallite as Template

Polyacrylamide (PAAm) hydrogels were synthesized by acrylamide polymerization in lyotropic liquid crystal (LLC) phase formed by surfactant Brij 58 solution. The morphology, structure and swelling property of the hydrogels were characterized. SEM images showed that photopolymerization of acrylamide monomers in organized assemblies with concentration between 10% and 40% formed highly ordered hydrogels. The pore size of the LLC hydrogels was 1～2 µm, which was about one fortieth of that of the traditional hydrogel. Phase reversal and phase separation occurred when concentration of Brij 58 was higher than 50%. Porosity of the hydrogels decreased with the increase of Brij 58 concentration. Characteristic peaks of FTIR spectra corresponding to carbonyl and amino groups shifted to lower wavenumber, indicating that more inter-molecular hydrogen bonds in LLC PAAm hydrogels. The LLC hydrogel kept the characteristic feature of sensitivity to pH as traditional hydrogel and a higher swelling ratio could be achieved.