【作者】 黄小娟；

【导师】 王吉德； 徐世美；

【作者基本信息】 新疆大学 ， 无机化学， 2008， 硕士

【摘要】 聚合物/粘土纳米复合材料因具有优异的力学性能及较低廉的生产成本,已成为近二十年来功能材料领域中基础研究和应用开发的热点。其中聚合物/膨润土复合水凝胶的研究备受关注,它利用膨润土的天然活性和价廉的特性,将其引入有机三维网络中制备复合水凝胶,可提高凝胶的吸水倍率和吸水速度、改善耐盐性能、凝胶强度及热稳定性。本文采用阳离子聚电解质取代传统的表面活性剂为插层剂,对钠基膨润土进行插层改性,制备聚阳离子/钠基膨润土纳米复合物。X射线粉末衍射(XRD)和透射电子显微镜(TEM)结果表明:阳离子聚电解质插入到膨润土的片层间,层间距扩大,片层结构被破坏,得到了剥离型的聚阳离子/钠基膨润土纳米复合物。不同分子量的聚阳离子对插层效果有很大的影响,可以通过控制聚阳离子分子量的大小,得到插层型或者剥离型的复合结构。将合成的聚合物/钠基膨润土纳米复合物与淀粉接枝丙烯酸网络互穿得到具有特殊半互穿结构的淀粉接枝丙烯酸/聚二甲基二烯丙基氯化铵/钠基膨润土两性半互穿纳米复合水凝胶。考察了合成条件对纳米复合水凝胶吸液性能的影响。结果表明:凝胶在去离子水中的最大吸水倍率为858g/g;在pH值为4~13较宽广的范围内,可保持较高的吸液倍率,在pH值13的溶液中,其吸液倍率为72 g/g;在浓度为0.1 mol/L的NaCl溶液中,吸液倍率可达81 g/g,呈现出一定的耐盐性;此外,在99%以上的含水量的条件下,纳米复合水凝胶的凝胶强度达到了28 kPa。为了提高水凝胶的吸液速度,以聚乙二醇(PEG)为生孔剂,通过生孔剂法制备了淀粉接枝丙烯酸/聚二甲基二烯丙基氯化铵/钠基膨润土多孔两性半互穿复合水凝胶。考察了PEG的分子量的、不同PEG的加入量及合成条件对凝胶孔的数目及孔径大小的影响。同时考察了多孔水凝胶的吸液动力学。由于孔状结构的存在,多孔水凝胶的吸水速度有了极大的提高,其达到饱和吸水量仅需10 min。以小分子单体甲醛和尿素通过单体插层缩聚法对膨润土进行插层处理,取得了良好的插层效果,之后将其与聚丙烯酸凝胶网络互穿制备了聚丙烯酸/脲醛树脂/钠基膨润土半互穿纳米复合水凝胶,并考察了膨润土的含量对凝胶吸液性能的影响。当膨润土的加入量为5 wt.%时,凝胶吸去离子水量为983 g/g。性能测试表明:在pH值为4~13较宽广的范围内,凝胶可保持较高的吸液倍率,在pH=13时,其吸液倍率为126 g/g;当NaCl的浓度为0.1 mol/L时,吸液倍率为113 g/g,呈现一定的耐盐性。更多还原

【Abstract】 In the last two decades, polymer/clay nanocomposites have been extensively investigated as advanced composite materials because these nanocomposites exhibit markedly improved mechanical property and reduce the cost of the manufacture. Among all the polymer/clay nanocomposites, the nanocomposite hydrogels based on bentonite have been more widely investigated. The properties of the hydrogels, e.g. salt-resistance, swelling capacity, absorbency rate, mechanical strength and thermal stability can be significantly enhanced by incorporation of bentonite into the polymer network, due to the natural activity and the low cost of the bentonite.Na-bentonite was modified by cationic polyelectrolyte though solution intercalation. The XRD pattern and TEM image indicated that the cationic polyelectrolyte was intercalated into the interlayer space of the Na-bentonite, the interlayer distance was enlarged, no basal reflection was observed in the XRD pattern and an exfoliated nanocomposite was obtained. The molecular weight of the cationic polyelectrolyte has a significant effect on the interlayer space of the nanocomposites. An exfoliated or intercalated structure can be obtained by controlling the molecular weight of the cationic polyelectrolyte.In order to improve the hydrogel strength and salt resistance, we prepared a novel amphoteric nanocomposite hydrogel with semi-interpenetrating polymer network (semi-IPN) which is composed of starch-g-acrylic acid (AA) and Na-BENT modified with linear polycations poly(dimethyldiallylammonium chloride )(PDMDAAC). The influences of the synthesis conditions on the swelling capacity of amphoteric superabsorbent composites were investigated in details. The results showed that the nanocomposite hydrogel has the swelling capacity of 858 g/g in deionized water. The hydrogel kept a high swelling in a wide pH range range of 4 to 13, and good salt tolerance. Swelling capacity was 72 g/g at the pH 13 and 81 g/g in 0.1 mol/L NaCl solution. Besides, the compressive strength of the hydrogel reached 28 kPa even under a more than 99% of water content.Amphoteric semi-IPN nanocomposite hydrogels with define porous structure composites of starch-g-acrylic acid/PDMDAAC/Na-bentonite were prepared in the presence of poly(ethylene glycol) (PEG) as the pore-forming agent. The influences of the PEG molecular weight, the amount of the PEG and the synthesis condition on porous structure are investigated. The PEG-modified hydrogels are characterized by swelling rate and swelling kinetics. The porous hydrogels reached its equilibrium swelling within 10 min.The urea and formaldehyde were used to modify Na-BENT by intercalative condensation, as the results of XRD and TEM showed an exfoliated nanocomposite FU/BENT was obtained. Then semi-IPN nanocomposite hydrogels prepared by interpenetrating with poly(acrylic acid) (PAA). The influences of the amount of Na-BENT on the swelling behavior of nanocomposite hydrogels were studied in details. When the amount of Na-BENT was 5 wt.%, the hydrogel has the swelling capacity of 983 g/g in deionized water. The nanocomposite hydrogel kept a high swelling in a wide pH range of 4 to 13 and good salt tolerance. Swelling capacity kept 126 g/g at the pH 131 g/g and in 0.1 mol/L saline solutions, respectively.更多还原