P（NIPAM-co-AA）水凝胶基无机/有机纳米复合材料的制备及其性能研究

【作者】 姜宇；

【导师】 刘守信；

【作者基本信息】 陕西师范大学 ， 物理化学， 2008， 硕士

【摘要】 聚合物基有机/无机纳米复合材料的组装以及相关的纳米技术在制备新型纳米复合材料中越来越受到研究者的关注。这是由于纳米无机物与聚合物基体之间的协同作用使得聚合物基复合材料把无机物的光、电、热等特性与高分子材料的韧性、易加工性、电绝缘性等性能巧g/k地结合起来,使材料既具有无机材料的优点（如刚性、高模量、尺寸稳定性、高热稳定性和特殊的光电磁性能等）又具有高分子材料的优点（如弹性、延展性、韧性、电绝缘性、易加工性等）。而且由于无机粒子在高分子基体中是以纳米粒子的形式均匀分布的,所以这种纳米复合材料在力学、热学、电学、光学、非线性光学等领域具有一定的应用。复合材料的性能在很大程度上取决于分散相尺寸和两相之间的界面作用,为了增强复合材料中各组分之间的相互作用,将一个或多个组分以纳米尺寸或分子水平均匀分散在另一组分的基体中,得到所谓的复合材料。复合材料的性质比相应的常规材料有了较大的改善,甚至表现出全新的性质。在制备有机/无机复合材料的诸多方法中,原位聚合法是目前较为可行的一种。原位聚合法可在温和条件下进行,可使两相分散均匀。该技术的实质是利用聚合物单体在外力作用下,如氧化、电、热、光、辐射、引发等,原位产生聚合或共聚,使得某一种或多种物质均匀分散在聚合物基体中,形成纳米复合材料。原位聚合技术的优点是:（1）制备工艺简单;（2）可制备较多体系的复合材料;（3）第二相或增强相表面洁净,分散均匀,相种类多,体积分数高;（4）可以制备金属或者陶瓷为第二相或增强相的聚合物基复合材料。基于以上研究背景基础上,本文采用溶胶-凝胶法制备了纳米TiO₂,研究了以PNIPAM、P（NIPAM-co-AA）为聚合物基体,先后以纳米TiO₂、无机粘土Clay为无机增强相,在引发剂作用下采用原位聚合法合成了几种聚合物基无机/有机纳米复合材料,主要研究内容包括以下三个方面:（1）以钛酸四丁酯为前驱物,冰醋酸为整合剂,盐酸作催化剂,乙醇作溶剂,采用溶胶-凝胶法制备了纳米TiO₂粉体,对TiO₂胶凝过程以及溶胶-凝胶转变机理进行了研究,初步探讨了影响溶胶-凝胶的实验因素。并且使用硅烷偶联剂对纳米TiO₂进行表面改性,使纳米TiO₂与偶联剂上的硅羟基缩聚形成Si-O-Ti键,从而将纳米TiO₂以化学健的形式引入至TiO₂/PNIPAM复合反应中。扫描电镜与透射电镜结果表明纳米TiO₂粒径均一、分散性良好;红外光谱显示硅烷偶联剂已经成功接枝到纳米TiO₂表面上;能谱分析结果证明了元素组成符合TiO₂的成分组成:XRD图谱显示了纳米TiO₂在不同温度下具有明显的晶型转变。（2）以PNIPAM为聚合物基体,表面经硅烷偶联剂改性后的纳米7i02为无机组分,在引发剂过硫酸氨（APS）引发作用下采用原位聚合法制备了不同纳米7i02含量的7i02/聚N-异丙基丙烯酰胺复合水凝胶。采用红外光谱、扫描电镜、紫外光谱、热重分析、动态粘弹谱仪（DMA）等表征了复合水凝胶的微观结构和形貌,测试了复合凝胶材料对紫外线的吸收、热稳定性、机械强度及其韧性。紫外吸收结果表明,纳米TiO₂粒子的引入,使得复合凝胶材料对紫外线吸收效果显著;热重分析测试显示了凝胶的热稳定性得到提高;DMA测试说明了复合凝胶的机械强度及其韧性得到明显改善。（3）以P（NIPAM-co-AA）为聚合物基体,无机粘土Clay为增强相,合成了一系列具有高吸水性和优异机械强度等性能的P（NIPAM-co-AA）/Clay复合水凝胶。利用粘土片层间阳离子的水化作用,使粘土的晶层结构在水中发生分离,其水分散体系与聚合物乳液均匀混合,晶层和聚合物乳液的粒子相互穿插,产生强烈的静电作用,从而形成纳米复合凝胶。其中,粘土取代传统有机交联剂BIS而扮演了无机组分和交联剂的双重角色,采用DMA、SEM、TG/DSC、IR和XRD等手段对复合凝胶进行了表征和测试。XRD曲线和IR光谱表明了粘土片层已被共聚物链段插层和剥离,形成了“三明治”插层结构,粘土片均匀分散在共聚物基质中;电镜照片显示了共聚物基质孔道更加密集,且孔道分散均匀;溶胀测试结果表明,随着粘土的加入,复合凝胶的溶胀度并没有受到很大影响,与传统共聚凝胶相比,甚至略有增加;机械性能测试结果说明,复合凝胶具有优异的机械强度和韧性,其模量随着粘土含量的增加而逐渐增大;同样,复合凝胶的热稳定性大大增强,TG/DSC曲线都表明了复合凝胶的热分解温度和熔点随着粘土含量的增加都有不同程度的提高,这归因于粘土与共聚物链段之间的作用并最终形成的插层结构。更多还原

【Abstract】 Assembly of inorganic-organic nanocomposites and relative nanotechnology have taken great advantage in the synthesis of novel nanocomposites and therefore aroused increasing attention among researchers.Due to the synergism of the polymer matrix and nanoinorganics,polymer based composites combined the advantages of the inorganic materials（rigidity,high module,good dimension stability,high thermal stability,unique optical property,electronic and magnetic properties） and the organic polymers（flexibility,ductility,electrical insulation,toughness and processability）,which are different from the single material and conventional composite materials. Moreover,these polymer based organic/inorganic nanocomposites have potential application in mechanical,thermal,electronic,optical,and nanolinear optical fields because the inorganic particles are well dispersed in polymer matrix in nanometer scale.The properties of composite were extremely determined by the dispersed particle size and the interracial action among the components in the nanocomposites,in order to increase the interfacial action among the components in the nanocomposites,the dispersion phase dimension was desired for nanometer level or molecule level. The properties of nanocomposites were improved greatly for the fine dispersion structure and strong interfacial interaction,even they owned some new special properties.In-situ polymerization is probablely a feasible method to prepare the inorganic-organic nanocomposite for its convenient condition and two phases could disperse homogeneously in composite system.The substance of the mentioned technic is polymerization or copolymerization happened during the monomers via external stimulation such as oxygenation,electricity,heat,ray, radiation and initiation.The superiorities of the in-situ polymerization are as follows:the first advantage is that the technic of preparation is simple,the second one is that this technic can be used to prepare the nanocomposites of the multi-system components,the third one is its variety types, uniform dispersion,lustration surface and high volume content of the second phase or enhanced phase in composite system,besides the forenamed merits,it is also can be applied for preparing the nanocomposite based on polymer matrix by using metal or ceramic as enhanced phase.Based upon above studies,in this thesis,we have prepared several kinds of polymer/inorganic nanocomposites,which are composed of PNIPAM,P（NIPAM-co-AA） as polymer matrix and nano TiO₂,Clay as enhanced phase via in-situ polymerization respectively.The thesis mainly includes following three parts:（1） Nano TiO₂ powder was prepared via sol-gel route,using TBT as precursor,HAc as chelated reagent,HCI as catalyzer,ethanol as solvent,also the mechanism of sol-gel route and the influenced preparation factors were discussed.The silane coupler was used to modify the surface of nano TiO₂, and the modified nano TiO₂ can be bond to the polymer by Si-O-Ti bond with the help of Si-OH of silane coupler.The SEM and TEM micrographs showed that the size of the nano TiO₂ particles dispersed uniformly and their distribution of particle size was really narrow.The IR spectrum revealed the Si-O-Ti bond between nano TiO₂ and silane coupler was formed.EDX results exhibited that the product was what we desired.XRD curves indicated the crystalloid of TiO₂ was affected mainly by the calcine temperature.（2） The composite hydrogels of poly（N-isopropylacrylamide）（PNIPAM） with nano-TiO₂ were prepared with PNIPAM as polymer matrix and nano TiO₂ as enhanced phase by the coupling copolymerization between PNIPAM and the pre-treated nano-TiO₂ particles with a silane coupling agent.The N,N’ -methylene bisacrylamide was used as crosslinking agent.The morphology,optical and mechanical properties of the composite hydrogels were studied by SEM,UV-VIS,FT-IR,and Dynamic Mechanical Analysis（DMA） method,respectively.The UV results showed that the composite hydrogels had a good absorption of UV,and TG curves revealed the thermal stability of nanocomposite increased largely,more over,their mechanical strength and toughness were improved markedly through DMA tests.（3） A series of P（NIPAM-co-AA）/Clay nanocomposite hydrogels（abbreviated as NAC） with high swelling ratio and excellent mechanical strength were prepared with PfNIPAM-co-AA) as polymer matrix,inorganic clay as enhanced phase via in-situ polymerization,and their characterization were tested by DMA,SEM,TG/DSC,IR and XRD.During the preparation process, the clay dispersed uniformly in water via the hydration of the cation between the layers,the separated layers penetrated further with polymer matrix,then the nanocomposite hydrogels were formed.In unique NAC gels network,the inorganic clay acted as a multifunctional crosslinker in place of an organic cross-linker（BIS） used in OR gels.The NAC gels exhibited excellent swelling ratio and it had no detectable change as altering the clay concentration,while the swelling ratio of NAC decreased slightly when the clay concentration was up to 25 wt%,which was consistent with the conclusion of SEM micrographs.XRD curves and IR spectrums showed that the clay was exfoliated and intercalated by copolymers,and the sandwich structure was formed.Furthermore, DMA results revealed the composite hydrogel had an excellent mechanical strength in a wide range of clay concentration,while the hydrogel moduli was improved with increasing clay concentration.更多还原