酶解木质素接枝聚丙烯酸多孔水凝胶的制备及表征

以N,N’-亚甲基双丙烯酰胺为交联剂对丙烯酸进行预聚,以Fe2SO4/H2O2体系引发酶解木质素(EHL)形成自由基,过硫酸铵为引发剂,将酶解木质素自由基与聚丙烯酸(PAA)进行接枝共聚制备酶解木质素接枝聚丙烯酸多孔水凝胶(EHL-g-PAA)。采用红外光谱(FTIR)、环境扫描电子显微镜(SEM)和热重分析(TG)进行表征,研究EHL和PAA质量比、pH值、温度对EHL-g-PAA溶胀性能的影响。结果表明:酶解木质素与聚丙烯酸接枝成功,形成了具有新型网络结构的EHL-g-PAA,EHL-g-PAA具有不规则分层次多孔结构。当EHL和PAA质量比为0.4∶1时,EHL-g-PAA的平衡吸水倍率最大。在室温下,EHL-g-PAA在蒸馏水中的平衡吸水倍率可达410.99,吸附达到平衡的时间延长到12 h,且EHL-g-PAA对水分的释放率达到93.88%。EHL-g-PAA具有良好的pH敏感性,在酸性以及碱性溶液中吸水能力降低,在中性条件下吸水能力最高。在低温条件下,EHL-g-PAA的网络舒张,吸水能力增加;在高温条件下,EHL-g-PAA的网络收缩,吸水能力降低。在高温低温交替的环境下,与PAA相比,EHL-g-PAA显示了良好的循环能力和较好的稳定性。 

Preparation and characterization of enzymatic hydrolysis lignin-based hydrogel

In order to prepare a new type of high absorption resin with porous structure, enzymatic hydrolysis lignin-based composite hydrogel ( EHL-g-PAA ) was prepared by grafting using enzymatic hydrolysis lignin and acrylic acid. Free radicals of enzymatic hydrolysis lignin were formed by the system of Fe2 SO4/H2 O2;acrylic was performed with ammonium persulfate ( APS) as initiator and N,N’-methylene double acrylamide ( EMB) as crosslinking agent;EHL-g-PAA was prepared using the free radicals of enzymatic hydrolysis lignin and acrylic prepolymer. EHL-g-PAA was characterized by FTIR, SEM and TG, and the effects of mass ratio of enzymatic hydrolysis lignin and acrylic acid, pH value and temperature on the swelling properties of EHL-g-PAA were investigated. The results showed that the enzymatic hydrolysis of lignin had been successfully polymerized, and formed a new network structure of the enzymatic hydrolysis lignin-based hydrogel. Composite hydrogel had irregular hierarchical porous structure. When the mass ratio of EHL and AA was 0. 4:1 , the water equilibrium absorption ability of EHL-g-PAA reached the maximum. Under room temperature of 20 ℃, water equilibrium absorption ability of EHL-g-PAA was 410. 99 in distilled water, the adsorption equilibrium time extended 12 hrs, and its release rate to water was 93. 88%. EHL-g-PAA showed good pH sensitivity. The ability to absorb water was lower in acid and alkaline solutions, and it reached the highest in neutral condition. Under low temperature conditions, the network diastole and water absorbing capacity of EHL-g-PAA increased; while under high temperature conditions, the network shrinkage and water absorption capacity of EHL-g-PAA decreased. Compared with PAA, EHL-g-PAA had better circulation ability and stability.