【作者】 林建桃；

【导师】 徐世美； 王吉德；

【作者基本信息】 新疆大学 ， 应用化学， 2009， 硕士

【摘要】 高吸水性凝胶是一种新型的亲水性的三维网络聚合物。由于化学交联的脆性,导致凝胶吸水后强度差,限制其在生物化学,人工软骨和其他方面的应用。如何在保持一定含水量的同时提高凝胶的强度,成为化学工作者在凝胶领域研究的重点。本文以无机粘土作为交联剂,采用自由基引发合成双交联剂聚丙烯酰胺,在不同无机交联剂Laponite和有机交联剂MBAM含量的情况下测试其在拉伸和压缩应力-应变曲线。同时考察无机粘土的交联性能和交联效率。并在碱性条件水解后测其压缩强度,吸液性能及其吸液动力学。通过研究表明,水解以后聚丙烯酰胺水凝胶在Laponite含量为10.7%,有机交联剂MBAM含量为0.02%时,压缩强度为8.26 KPa,吸水率为459.8 g/g,,吸盐66.7 g/g。水解双交联剂聚丙烯酰胺吸液速率较快,且扩散过程多表现为non-Fickian扩散。为进一步研究粘土的交联作用,同时为提高凝胶的综合性能,我们引入不同单体的双网络结构来提高凝胶的强度和吸液性能。采用以粘土为交联剂的PAAm网络作为第一网络,而在第二网络用MBAM做交联剂合成PAA双网络结构水凝胶。通过研究表明,在无机粘土含量为5%,有机含量为0.05%,凝胶在含水量为99.58%,压缩强度为21.5 KPa,在蒸馏水中的吸液倍率为1219 g/g,在0.9 wt%NaCl的吸液倍率为124 g/g。而吸水达到平衡时间比双交联剂聚丙烯酰胺所用时间要少。采用不同的合成方法,我们构建了以分别以粘土和MBAM为交联剂的PAAm-PAMPS双网络凝胶,与PAAm-PAA双网络凝胶相比,第一网络较为紧密。在粘土含量为13.8%,而MBAM含量为1.8%下所得的凝胶表现出较高的机械强度,在含水量为99.3%时的压缩强度为87.58 KPa,最大吸水量为195.2 g/g。更多还原

【Abstract】 Hydrogels are a new kind of three-dimensional hydrophilic crosslinked polymers. The low fracture toughness of chemically crosslinked hydrogels restricts their application in biomedicine, organ engineering and other fields. Many efforts have been made to increase the mechanical strength of hydrogels by the introduction of inorganic nanoclay into organic polymer networks and double network.At first, polyacrylamide nanocomposite hydrogels with two crosslinkers, Laponite and MBAM, was prepared by free radical initiation. Different crosslinkers contents were investigated in terms of tensile and compressive strength. In addition, the PAAm hydrogels were hydrolyzed and the swelling capacity, mechanical strength and the swelling dynamics were studied. The results indicated that a compressive stress of 8.26 KPa was obtained with 10.7% Laponite and 0.02% MBAM. In addition, the swelling capacity was 459.8 g/g in distilled water and 66.7 g/g in 0.9% NaCl. The swelling of the hydrolyzed PAAm hydrogel was faster and the diffusion behaviors obeyed non-fickian type. To investigate the crosslinking effect of Laponite further and enhance the comprehensive performance, the double network composed of different monomers was introduced. A novel double network nanocomposite hydrogel consisting of the first network of PAAm using laponite as a crosslinker and the second network of PAA using MBAM as a crosslinker was synthesized by two-step solution polymerization. The resulting PAAm-PAA double network nanocomposite hydrogels showed an excellent swelling capacity of 1219 g/g in deionized water, 124 g/g in 0.9 wt% NaCl solution while 21.5 KPa high compressive stress in a high water content of 99.58% was achieved when 5 wt% laponite and 0.05 wt% MBAM were used during the polymerization respectively. But the time to reach swelling equilibrium is shorter than hydrogel with two crosslinkers.Based on PAAm-PAA double network nanocomposite hydrogels, PAAm-PAMPS hydrogels were prepared by different methods by which the first network of PAAm was denser in contrast to the one in PAAm-PAA. The results showed the hydrogel had a high compressive stress of 87.58 KPa in high water content of 99.3% while the swelling capacity in deionized water is 195.2 g/g when the contents of laponite and MBAM were 13.8% and 1.8%, respectively..更多还原