Bioengineering Functional Copolymers. IX. Synthesis and Characterization of Stimuli-Responsive Poly N-isopropylacrylamide-co-N-vinyl-2-pyrrolidone and Its Cu II Complexes

Authors : Zakir Mo RZAYEV, Betül Kırcı DENİZLİ, Haluk DENİZLİ

Pages : 99-115

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Publication Date : 2008-04-01

Article Type : Research Paper

Abstract :Radical copolymerization of N-isopropylacrylamide NIPA with N-vinyl-2-pyrrolidone VP were carried out with 2,2’azobisisobutyronitrile AIBN as an intiator in N,N’-dimethylformamide solution at 65oC under nitrogen atmosphere.Cu II –copolymer macrocomplexes were prepared by incorporation of copolymers with copper sulfate in aqueoussolution at 40oC. Structure and composition of the obtained copolymers, and the formation of coordinated Cu II complexes between amide VP unit and Cu II ions were studied by FTIR spectroscopy, DSC and TGA-DTG methods,as well as by the electrical conductivity measurements. Compositon of the copolymers synthesized in a wide rangeof monomer feed ratios were determined by FTIR and1H 13C NMR–DEPT-135 spectroscopy. The monomer reactivityratios were determined by Fineman-Ross, Kelen-Tüdös and non-linear regression methods. It was observed thatstudied monomer pair has some tendency to alternation in the chosen monomer feed ratios due to formation ofintermolecular interaction through H-bonding and N→O=C coordination. The copolymers predominantly showamorphous structure while their Cu II –macrocomplexes exhibit crystalline phase. The conductive properties of thesynthesized Cu II –poly VP-co-NIPA complexes was also discussed.The synthesized poly NIPA-co-VP s showtemperature sensitiveness Ts and higher glass-transition temperature Tg and thermal stability, polyelectrolyte andstimuli-responsive temperature- and pH-sensitive behavior, and can be attributed to the class of bioengineeringfunctional copolymers useful for application in various gene- and bioengineering processes, drug delivery systems,and biomacromolecule conjugations
Keywords : Functional copolymers, stimuli responsive, poly NIPA, N vinyl 2 pyrrolidone, Cu II complexes