The polymer functionalized multiwalled carbon nanotubes have been prepared by controlled graft copolymerization of N-isopropylacrylamide and acrylic acid monomers from their mixture at fixed and variable feed composition. The presence of acrylic acid has enhanced the activity of N-isopropylacrylamide for graft copolymerization (52%) on multiwalled carbon nanotubes in comparison to graft copolymerization of N-isopropylacrylamide (38 %) in absence of acrylic acid. The atom transfer radical graft copolymerization of N-isopropylacrylamide and acrylic acid monomers has produced graft copolymers (Scheme 1) with high molecular weight (42x103 g mol-1) and low molecular weight dispersity (1.13) at fixed feed molarity (0.1M ) and composition. The copolymer grafted multiwalled carbon nanotubes have shown high dispersity in water in comparison to pristine multiwalled carbon nanotubes. The grafted poly(N-isopropylacrylamide-co-acrylic acid) were characterized by FT-IR for structural information (Figure 1) and variation in thermal stability is evaluated by thermogravimetric analysis. Poly(N-isopropylacrylamide-co-acrylic acid) grafted multiwalled carbon nanotubes were used to control the sensitivity and selectivity of glassy carbon electrode in cyclic voltammetric detection of dopamine in presence and absence of interfering ascorbic acid in phosphate buffer solution. The modified glassy carbon electrode has shown improved sensitivity and working range with a response time of 4 seconds in comparison to unmodified glassy carbon electrode. The presence of acrylic acid on multiwalled carbon nanotubes has improved the selectivity of electrode for dopamine. These studies have clearly indicated that multiwalled carbon nanotubes with controlled molecular weight and structures of poly (N-isopropylacrylamide-co-acrylic acid) could be useful in cyclovoltammetric detection of dopamine in presence of ascorbic ascorbic acid at different temperature and pH.

Controlled graft copolymerization on multiwalled carbon nanotubes from binary mixture of monomers

248th National Meeting (2014)

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