氧化石墨烯基纳米复合水凝胶的制备及其性能研究
发布时间：2018-10-22 11:05
【摘要】：高分子水凝胶是一类具有三维网络结构的水溶胀型功能高分子材料,其网络结构的主链或侧链连有诸如羟基、酰胺基、羧基、磺酸基等亲水基团,能够吸附相当于自身质量几十到几百倍甚至上千倍的水或水溶液。并且在一定压力条件下,仍具有良好的吸水、保水性能。而在实际的使用过程中,由于水体的金属离子、p H值等外界因素使得高分子水凝胶网络塌陷而造成材料失去吸水保水能力,成为制约其实际应用的瓶颈因素。研究证明,向高分子水凝胶引入纳米填充体是提高其吸水性和耐盐性的一种有效手段。氧化石墨烯(GO)是一种单原子层厚度的二维纳米材料,它具有石墨烯的稳定结构和良好的力学性能,同时由于其含有大量的亲水性含氧官能团,在水中具有极好的分散性,为GO与其它亲水性物质在水相中进行反应、掺杂等制备纳米复合材料提供了可能。基于此,本论文以GO或化学改性的GO为纳米填充体,通过原位聚合或共聚等方法制备一系列GO基纳米复合水凝胶,研究GO对纳米复合水凝胶物化性能以及吸水、耐盐等溶胀性能的影响。在此基础上,研究其在纯水、盐溶液环境下,纳米复合水凝胶网络中的GO片层对聚合物网络溶胀、塌陷产生的影响,以期构建纳米复合水凝胶结构-性能关系。主要研究内容和结果包括:(1)以GO为填充体,丙烯酸、丙烯酰胺为聚合单体,N,N-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,分别制备了聚丙烯酸-氧化石墨烯(PAA-GO)和聚丙烯酰胺-氧化石墨烯纳米复合水凝胶(PAM-GO)。GO纳米片在聚合物中分散均匀,纳米复合水凝胶呈现出无定形结构。结果发现,添加极小量的GO(0.073 wt%)就可以大大的提高了水凝胶的吸水能力,主要归因于亲水的GO纳米片可有效的改善水凝胶的网络结构,从而能够吸收更多的水分;引发剂和交联剂的加入量对纳米复合水凝胶网络结构的影响则与纯有机水凝胶相似:随着引发剂加入量的增加,纳米复合水凝胶的吸水能力先增加后减小,而交联剂的加入量与纳米复合水凝胶的吸水能力成反比。在耐盐性方面,GO纳米片在纳米复合水凝胶网络结构中起到“非离子”性填充体的作用,从而有效地防止了网络结构的坍塌,提高了纳米复合水凝胶的耐盐性。通过有机溶液中溶胀行为的研究发现,GO纳米片的引入也能够改善PAA-GO、PAM-GO纳米复合水凝胶在有机溶剂/水体系中的结构坍塌和变形。一方面,GO表面的亲水官能团与聚合物链上的官能团结合,提高了整个聚合物网络的强度,另一方面,GO的二维纳米结构能够起到“house-of-cards”的作用,有效地阻止了自由水分子从网络中被“挤出”。(2)以GO为填充体,N,N-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,丙烯酸、丙烯酰胺共聚制备了聚(丙烯酸-co-丙烯酰胺)/氧化石墨烯(PAAM-GO)纳米复合水凝胶,呈现层状三维网状结构。在凝胶的形成过程中引发剂含量、单体比例、交联剂含量及GO浓度对于制备得到的PAAM-GO纳米复合水凝胶的吸附性能均有很大的影响。在引发剂含量为64 mg、交联剂含量为12.8 mg、单体(丙烯酸:丙烯酰胺)摩尔比例为0.5、GO浓度为0.5 mg m L-1时制备得到的PAAM-GO纳米复合水凝胶对于水的吸附量最大为197 g g-1。在聚合体系中加入GO可以使水凝胶形成更加稳定的三维网络结构,在外界溶液条件发生变化时有效防止水凝胶网络结构的坍塌,进而提高了纳米复合水凝胶的综合吸附性能。(3)利用重氮化反应对GO表面进行改性,以其为填充体,N,N-亚甲基双丙烯酰胺为交联剂,过硫酸铵为引发剂,丙烯酸为聚合单体制备了聚丙烯酸-改性GO纳米复合水凝胶。改性GO与PAA具有良好的兼容性,改性GO的加入有效地提高了纳米复合水凝胶的综合吸附性能。(4)通过原位聚合方法,在大气氛围下,通过掺杂十八烷基胺改性的氧化石墨烯(GO/ODA),合成了具有耐盐性的聚丙烯酰胺/聚乙二醇-十八烷基胺改性GO互穿网络水凝胶(PAM/PEG-GO/ODA)。掺杂GO/ODA可显著提高PAM/PEG-GO/ODA的耐盐性和吸水性能。其中,在Ca Cl2水溶液中吸水倍率可提高60%以上。当GO/ODA添加量为5 wt%时,其耐盐性提高一倍,达到61g g-1。PAM/PEG-GO/ODA具有亲水疏油性质,对油品中的水具有优异的选择性,除水率达到99%以上。(5)制备了聚乙烯醇/聚乙烯吡咯烷酮-GO互穿网络水凝胶(PVA/PVP-GO),通过冷冻干燥法制造出丰富贯穿孔结构。GO含量对PVA/PVP-GO的孔道结构有较大影响,在GO浓度较低时PVA/PVP-GO呈现出许多较大的孔道,但随着GO浓度的增大复合凝胶的孔道结构明显减小呈现出贯穿的峰窝状结构。相比于聚乙烯醇/聚乙烯吡咯烷酮(PVA/PVP)水凝胶而言,与GO复合的PVA/PVP水凝胶在相同条件下具有更优异的吸水性能,GO的加入有效地改善了PVA/PVP结构的坍塌和变形,这说明在PVA/PVP水凝胶体系中加入GO可以明显提高PVA/PVP水凝胶的耐盐性。利用其大孔结构和表面亲水疏油性质,PVA/PVP-GO可用来过滤柴油中的水,含水率由0.094 g g-1下降到37.95 ppm,除水率达到99.95%,PVA/PVP-GO对油品中的水具有优异的选择性。
[Abstract]:High molecular hydrogel is a kind of water-swellable functional polymer material with three-dimensional network structure, capable of adsorbing water or an aqueous solution equivalent to tens to hundreds or even thousands of times of its own mass. and has good water absorption and water retention performance under certain pressure conditions. In the actual use process, because of the metal ion, p H value and other external factors of the water body, the polymer hydrogel network collapses to cause the material to lose water-absorbing and water-retaining ability, and becomes the bottle-neck factor restricting its practical application. It has been proved that the introduction of nano-fillers into polymer hydrogels is an effective method to improve water absorption and salt tolerance. the graphene oxide (GO) is a two-dimensional nano material with a single atomic layer thickness, It is possible to prepare nano-composites by reacting GO with other hydrophilic substances in aqueous phase. Based on this, GO or chemically modified GO was used as a nano-filler, and a series of GO-based nanocomposite hydrogels were prepared by in-situ polymerization or copolymerization, and the effects of GO on physical and chemical properties of nano-composite hydrogel and swelling properties of water absorption and salt resistance were studied. On the basis of this, the effect of GO layer on swelling and collapse of polymer network was studied under pure water and salt solution environment, with a view to constructing nano composite hydrogel structure-performance relationship. The main research contents and results are as follows: (1) GO as filler, acrylic acid, polymerization monomer as polymerization monomer, N, N-methylene bispecific as cross-linking agent, over-polymerization as initiator, Polyacrylic acid-graphene oxide (PAA-GO) and poly (ethylene oxide-graphene) nano composite hydrogel (PAM-GO) were prepared respectively. The GO nano-sheets were dispersed uniformly in the polymer, and the nano composite hydrogel exhibited an amorphous structure. As a result, it was found that adding a very small amount of GO (0.073 wt%) can greatly improve the water-gel ability of hydrogel, mainly due to hydrophilic GO nano-sheet can effectively improve the network structure of hydrogel, so that more water can be absorbed; the influence of initiator and cross-linking agent on the network structure of nano composite hydrogel is similar to that of pure organic hydrogel, and the addition amount of the cross-linking agent is inversely proportional to the swelling capacity of the nano composite hydrogel. In the aspect of salt tolerance, GO nano-sheets play a role in the network structure of nano-composite hydrogel "Non-ionic" and the salt tolerance of the nano composite hydrogel is improved. The research of swelling behavior in organic solution shows that the introduction of GO nano-sheet can also improve the structure and deformation of PAA-GO, PAM-GO nano composite hydrogel in organic solvent/ water system. On the one hand, the hydrophilic functional group on the GO surface is combined with the functional group on the polymer chain, so that the strength of the whole polymer network is improved; and on the other hand, the two-dimensional nano structure of the GO can play the role of 鈥渉ouse-of-cards鈥，
本文编号：2286975
[Abstract]:High molecular hydrogel is a kind of water-swellable functional polymer material with three-dimensional network structure, capable of adsorbing water or an aqueous solution equivalent to tens to hundreds or even thousands of times of its own mass. and has good water absorption and water retention performance under certain pressure conditions. In the actual use process, because of the metal ion, p H value and other external factors of the water body, the polymer hydrogel network collapses to cause the material to lose water-absorbing and water-retaining ability, and becomes the bottle-neck factor restricting its practical application. It has been proved that the introduction of nano-fillers into polymer hydrogels is an effective method to improve water absorption and salt tolerance. the graphene oxide (GO) is a two-dimensional nano material with a single atomic layer thickness, It is possible to prepare nano-composites by reacting GO with other hydrophilic substances in aqueous phase. Based on this, GO or chemically modified GO was used as a nano-filler, and a series of GO-based nanocomposite hydrogels were prepared by in-situ polymerization or copolymerization, and the effects of GO on physical and chemical properties of nano-composite hydrogel and swelling properties of water absorption and salt resistance were studied. On the basis of this, the effect of GO layer on swelling and collapse of polymer network was studied under pure water and salt solution environment, with a view to constructing nano composite hydrogel structure-performance relationship. The main research contents and results are as follows: (1) GO as filler, acrylic acid, polymerization monomer as polymerization monomer, N, N-methylene bispecific as cross-linking agent, over-polymerization as initiator, Polyacrylic acid-graphene oxide (PAA-GO) and poly (ethylene oxide-graphene) nano composite hydrogel (PAM-GO) were prepared respectively. The GO nano-sheets were dispersed uniformly in the polymer, and the nano composite hydrogel exhibited an amorphous structure. As a result, it was found that adding a very small amount of GO (0.073 wt%) can greatly improve the water-gel ability of hydrogel, mainly due to hydrophilic GO nano-sheet can effectively improve the network structure of hydrogel, so that more water can be absorbed; the influence of initiator and cross-linking agent on the network structure of nano composite hydrogel is similar to that of pure organic hydrogel, and the addition amount of the cross-linking agent is inversely proportional to the swelling capacity of the nano composite hydrogel. In the aspect of salt tolerance, GO nano-sheets play a role in the network structure of nano-composite hydrogel "Non-ionic" and the salt tolerance of the nano composite hydrogel is improved. The research of swelling behavior in organic solution shows that the introduction of GO nano-sheet can also improve the structure and deformation of PAA-GO, PAM-GO nano composite hydrogel in organic solvent/ water system. On the one hand, the hydrophilic functional group on the GO surface is combined with the functional group on the polymer chain, so that the strength of the whole polymer network is improved; and on the other hand, the two-dimensional nano structure of the GO can play the role of 鈥渉ouse-of-cards鈥，
本文编号：2286975
本文链接：https://www.wllwen.com/shoufeilunwen/gckjbs/2286975.html
