Controlled Fabrication Of Molecularly Imprinted Polymers On The Surface Of Multi-walled Carbon Nanotubes

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.