【作者】 许建雄；

【导师】 黎华明；

【作者基本信息】 湘潭大学 ， 高分子化学与物理， 2010， 硕士

【摘要】 碳纳米管(CNTs)由于其独特的性能和极大的比表面积,在分子印迹领域显示出广阔的应用前景。但目前,关于CNTs表面分子印迹聚合物的研究才刚起步,主要通过CNTs表面自由基共聚合接枝分子印迹聚合物(MIPs)。不过在聚合反应体系中,“溶液聚合”现象无法避免以及存在聚合物膜不均匀等缺点,严重影响了表面分子印迹聚合物的印迹效率。本论文分别采用原子转移自由基聚合(ATRP)和可逆加成-断裂链转移(RAFT)聚合反应,在多壁碳纳米管(MWNTs)表面接枝MIPs,以期得到具有优异印迹效率的印迹聚合物材料。具体内容如下:(1)MWNTs表面接枝茶碱分子印迹聚合物。利用酸氧化后MWNTs表面的羧基与2-溴代异丁酸乙二醇酯之间的反应,合成ATRP引发剂修饰的碳纳米管(MWNT-Br)。以MWNT-Br为大分子引发剂、丙烯酸羟乙酯(HEMA)为功能单体,双丙烯酸乙二醇酯(EGDMA)为交联剂,在模板分子茶碱存在下,通过ATRP反应在MWNTs上接枝茶碱分子印迹聚合物膜(MWNT-TMIPs)。采用透射电镜(TEM)对合成的MWNT-TMIPs进行表征,结果显示MWNTs表面接枝上了一层均匀的印迹聚合物膜,膜厚约为5 nm。采用静态吸附的方法对所合成的MWNT-T-MIPs印迹效率进行了评价,结果表明MWNT-TMIPs对茶碱分子具有较高的印迹吸附量和选择性吸附能力。吸附动力学研究表明,MWNT-TMIPs对茶碱分子具有快速的初始吸附速度,在60 min内基本达到吸附平衡,明显优于溶液聚合方法合成的MIPs。(2)MWNTs表面接枝Nα-叔丁氧基-L-色氨酸(n-Boc-Trp-OH)分子印迹聚合物。首先利用过量的乙二醇对羧基化的MWNTs进行修饰合成出表面含有羟基的MWNTs(MWNT-OH),再利用小分子RAFT试剂S,S’-双(2-甲基-2-丙酸基)三硫代碳酸酯与MWNT-OH反应,合成RAFT试剂修饰的MWNTs(MWNT-RAFT)。采用傅立叶红外光谱(FTIR)、热重分析(TGA)、X射线光电子能谱(XPS)对合成的MWNT-RAFT进行表征。结果表明,MWNTs表面RAFT试剂的接枝量为71μmol/g。以MWNT-RAFT为链转移剂、丙烯酰胺(AM)为功能单体、N,N-二亚甲基双丙烯酰胺(MBA)为交联剂、n-Boc-Trp-OH为模板分子,通过RAFT聚合在MWNTs表面接枝MIPs,并对聚合条件进行了初步探索。更多还原

【Abstract】 In recent years, carbon nanotubes (CNTs) have been the subject of intense interests due to their exceptional thermal stability, remarkable mechanical and electronic properties. These properties as well as extremely high surface-to-volume ratio of CNTs make them excellent support candidates in preparing molecularly imprinted polymers (MIPs). Grafting of MIPs film onto the surfaces of CNT support would endow MIPs with large surface area. The most common method for grafting MIPs on the surface of CNTs is surface-confined radical copolymerization. However, bulk polymerization can not be avoided and relatively low controllability of the reaction make the grafted MIPs have heterogeneous networks in some microdomain, these would be harmful to the recognition ability of the MIPs. In this paper, MIPs are successfully grown from the surface of muti-walled carbon nanotubes (MWNTs) via atom transfer radical polymerization (ATRP) and reversible addition-fragmentation transfer (RAFT) polymerization. The main contents are as follows:(1) Controlled fabrication of theophylline imprinted polymers on MWNTs via ATRP. Theophylline imprinted polymers are synthesized on the surface of multiwalled carbon nanotubes via ATRP using brominated multiwalled carbon nanotubes as an initiator. The nanotube-based initiator is prepared by directly reacting acyl chloride-modified MWNTs with 2-hydroxylethyl-2’-bromoisobutyrate. The grafting copolymerization of 2-hydroxyethyl-2-methyl-2-propenoate and ethylene glycol dimethacrylate in the presence of template theophylline lead to thin molecularly imprinted polymer films coating MWNTs. The thickness of molecularly imprinted polymer films prepared in this study is about 5 nm as determined by transmission electron microscopy. The adsorption properties, such as adsorption dynamics, special binding and selective recognition capacity, of the as-prepared molecularly imprinted polymer films are evaluated. The results demonstrate that the composite of MIPs and MWNTs not only possess a rapid dynamics but also exhibit a good selectivity toward theophylline, compare to caffeine.(2) Sythesis of Nα-(tert-butoxycarbonyl)-L-tryptophan imprinted polymers on the surface of MWNTs via RAFT polymerization. Nα-(tert-Butoxycarbonyl)-L-tryptophan imprinted polymers are synthesized on the surface of MWNTs via RAFT polymerization. The RAFT agent functionalized MWNTs are prepared by directly reacting hydroxyl-modified MWNTs with S,S’-bi(2-methyl-2-propcarboxyl) trithiocarbonate. The grafting copolymerization of acrylamide and N,N’- methylenebis(acrylamide) in the presence of Nα-(tert-butoxycarbonyl)-L-tryptophan lead to molecularly imprinted polymer coating MWNTs. Preliminary exploration of the grafting condition has been studied.更多还原