【作者】 董晶；

【导师】 陈莉；

【作者基本信息】 天津工业大学 ， 材料学， 2004， 硕士

【摘要】 本论文从合成N-异丙基丙烯酰胺（NIPA）与葡聚糖的共聚及互穿（IPN）水凝胶出发，研究环境刺激下凝胶的溶胀、吸附行为，并进一步探索其在生物分离中的应用。 本文采用甲基丙烯酸环氧丙酯（GMA）对葡聚糖（Dextran 40000）进行化学改性，合成出了具有反应活性的葡聚糖衍生物（GMA-Dex）；使用过硫酸铵和N，N，N’，N’-四甲基乙二胺作为氧化还原引发剂引发GMA-Dex与NIPA聚合，合成出了质量比r（r=GMA-Dex/（GMA-Dex+NIPA））分别为0.2、0.4、0.5、0.6和0.8的新型共聚水凝胶（P（NIPA-co-GMA-Dex））。利用红外光谱（IR）分析和核磁共振（¹H-NMR）等方法对GMA-Dex及P（NIPA-co-GMA-Dex）凝胶的结构和组成进行了表征，并分别考察了不同r值对凝胶的较低临界溶解温度（LCST）、溶胀性、退溶胀/再溶胀动力学等性能的影响。结果发现，P（NIPA-co-GMA-Dex）凝胶具有温度敏感性，pH值敏感性和离子强度敏感性。同时，P（NIPA-co-GMA-Dex）水凝胶对温度的响应还具有很好的可逆性。室温（20℃）时，P（NIPA-co-GMA-Dex）凝胶具有较高的溶胀率，而且r越大，凝胶的溶胀率越小。P（NIPA-co-GMA-Dex）凝胶的LCST均大于PNIPA凝胶的LCST（32℃），并且随r的增大而增大。退溶胀动力学的研究结果表明在50℃时，凝胶剧烈收缩，并且其r越大，凝胶退溶胀越慢，水保留率越高。再溶胀过程中，凝胶的再溶胀速率随着r的增大而增大，但均低于PNIPA凝胶再溶胀速率。此外，通过变化氯化钠的浓度来改变溶液的离子强度，研究了离子强度对P（NIPA-co-GMA-Dex）凝胶溶胀率的影响。发现所有凝胶都具有相似的变化趋势，当离子强度低于0.5mol L^-1时，凝胶具有较高的溶胀率；而当离子强度逐渐增大至2mol L^-1时，凝胶溶胀率则显著变小，其中r=0.8凝胶的溶胀率仅为其在水中溶胀率的1/10。 本文成功合成了GMA-Dex与PNIPA的互穿/半互穿凝胶，并对凝胶的溶胀性能进行了研究，发现PNIPA/GMA-Dex半IPN和IPN凝胶同样具有对温度敏感的特性。改变NIPA和GMA-Dex的配比对凝胶的溶胀率、退溶胀率和再溶胀率都有很大的影响。一般的GMA-Dex的质量百分比c越大，凝胶的溶胀率越小，LCST越高，退溶胀、再溶胀速率越慢。 通过凝胶的单轴压缩实验对P（N IPA一co一GMA一Dex）凝胶的力学性能进行了研究。发现P（N IPA一co一GMA一Dex）凝胶具有较好的力学性能，其剪切模量和有效交联密度均随着r的增加而增大。 本文对P困IPA一co一GMA一Dex)凝胶在生物分离中的应用进行了初步的研究。结果表明P困IPA一co一GMA一Dex)凝胶与十二烷基硫酸钠（SDS）、芦丁和丙氨酸之间的相互作用具有明显的对温度的依赖性，当温度高于凝胶的LCST时，凝胶与SDS、芦丁和丙氨酸之间的相互作用显著增强，对它们的吸附量也会相应增加，这种特性有望在生物大分子的纯化、分离等领域得到实际应用。通过考察P伽IPA一co一GMA一Dex)凝胶对多糖和蛋白质的浓缩分离行为发现，P伽IPA一co一GMA一Dex)凝胶对多糖和蛋白质的分离效率在LCsT附近发生突跃，显示出较好的浓缩分离能力。更多还原

【Abstract】 The synthesis and properties of poly (NIPA-co-GMA-Dex) hydrogels and PNIPA/GMA-Dex IPN/semi IPN hydrogels, including the swelling and absorbing behaviors in response to environmental stimuli were studied. The applications of poly (NIPA-co-GMA-Dex) hydrogels in bioseparation were also investigated.Glycidyl methacrylate (GMA) derivatized dextran (GMA-Dex) was synthesized by coupling GMA to dextran in the presence of 4-(N,N-dimethylamino) pyridine using DMSO as an aprotic solvent. Through copolymerization of this active monomer with N-isopropylacrylamide (NIPA) in aqueous solution, a series of novel hydrogels (poly (NIPA-co-GMA-Dex)) with different weight ratio r(r=GMA-Dex/(GMA-Dex+NIPA)) were prepared using radical polymerization method. Both GMA-Dex monomer and poly (NIPA-co-GMA-Dex) gels were characterized using FTIR spectra and 1H-NMR, and the influence of r on the swelling ratio (SR), deswelling/reswelling kinetics has been studied. It is found that poly (NIPA-co-GMA-Dex) gels are temperature-, pH- and ionic strength-sensitive. Their SR(20℃C) decreased and the lower critical solution temperature(LCST) increased with increase of r, and the LCSTs of poly (NIPA-co-GMA-Dex) gels are all higher than that of PNIPA gel(32℃). The smaller the r is, the faster the gels deswell; but the reswelling speed increased with increase of r. The results also indicated that the SR of poly (NIPA-co-GMA-Dex) gels was affected by ionic strength of solution. When ionic strength<0.5mol L-1, the SR remained high; when ionic strength was increased to 2mol L-1 gradually, the gels shrinked significantly.PNIPA/GMA-Dex IPN/semi-IPN gels were also synthesized successfully. The influence of c (weight concentration of GMA) on SR, deswelling/reswelling kinetics has been studied. It has found that PNIPA/GMA-Dex IPN/semi-IPN gels are also temperature-sensitive. The SR and deswell/reswell speeds are affected greatly by the component of the hydrogel.The mechanical properties of poly (NIPA-co-GMA-Dex) hydrogels were investigated using uni-axis compressive experiments in this study. We found that poly (NIPA-co-GMA-Dex) hydrogel show much better mechanical properties than PNIPA hydrogel, which is too soft to measure. The shear modulus and the effective cross-linking density increased with the increase of r.The applications of poly (NIPA-co-GMA-Dex) hydrogels in bioseparation have been investigated. The results indicated that the interactions between poly (NIPA-co-GMA-Dex) hydrogels and sodium dodecylsulfate (SDS) or Rutin or DL-a -Alanine show obvious dependence on the temperature. At higher temperature(>LCST), poly (NIPA-co-GMA-Dex) hydrogels deswelled and were susceptible to absorb larger amount of SDS or Rutin or DL- a -Alanine, some of them could be desorbed at lower temperature(<LCST). The extent of adsorption was found to depend on the temperature and the concentration of SDS or Rutin or DL- a -Alanine solution. This characterization can be expected to apply to the purification and separation of biomacromolecules. In addition, the gel-extraction separation of Dextran 40 and Bovine serum albunin (BSA) were also studied. The experimental results showed that poly (NIPA-co-GMA-Dex) hydrogels had excellent separation property for the Dextran and BSA. The separation efficiency happened abruptly around the LCST.更多还原