Investigation of thermal and electrical behaviors of functionalized multi walled carbon nanotubes-polymer composites

Investigation of Thermal and Electrical Behaviors of Functionalized Multi Walled Carbon Nanotubes-Polymer Composites In this study, polymer grafting to multiwalled carbon nanotube (MWNT) was achieved by grafting from method. For this aim, the multiwalled carbon nanotube was reacted by oxidizing acids such as HNO3/H2SO4, and -COOH group was introduced to MWCNT. Then, the MWNT-COOH converted to an acylchloride derivative with SOCl2 was reacted by ethylene glycol. The ring open polymerization (ROP) was achieved by using ε-caprolacton in presence of Sn(Oct)2 as catalyst and the MWNT-COOH prepared in this study, and later it was created a core for initiator of atom transfer radical polymerization by making end acylation with α-bromopropyonyl bromide in presence of sodium carbonate as catalyst. The MWCNT-PCL-b-PSt-b-PGMA triblock copolymer was produced as result of polymerization of first styrene and later glycidyl methacrylate via product prepared using CuBr/2,2´-bipyridyne as catalyst and a macroinitiator for ATRP. The nanocompozits were prepared from triblock copolymers with content % 1, % 3, % 5 and % 7 MWNT-COOH. In the other part of this study, theirs copolymers in the different ratios of glycidyl methacrylate and styrene were prepared by free radical polymerization method using azobisizobutyronitryle (AIBN) as initiator. The MWNT-COOH was converted form a acid ended nanotup to an amine ended strucuture ((MWCNT-Si-NH2). The amine ended nanotup was modified by poly(glycidyl methacrylate -co-styrene). The nanocompozits were prepared from copolymers with different compositions by using ratios of % 3, % 5, % 8 and % 12 MWNT-Si-NH2. A copolymer containing bisphenol-A propoxilat diglycidyl ether and piperazine was synthesized. Nanocompozits were prepared from synthesized copolymers with a mixture of MWNT-COOH and MWNT-Si-NH2 containing totaly % 2, % 5,% 10, %,15 and % 20 by weight. In the other part of this investigation, a shiff-base was produced from reaction of p-toluidyne and benzaldehyde. Furthermore, monomer was synthesized from its reaction with acryloyl chloride in the presence of triethylamine, and monomer was polymerized by free radical polymerization method. It was converted to its metal complex by using Ni(CH3COO)2.4H2O. Nanocompozits containing the MWNT-Si-NH2 in ratios of % 2, % 8 and % 15 (by weight) using prepared polymeric complex were produced. All the structures synthesized were caharacterized by FT-IR, and also soluble substances were characterized by 1H-NMR and 13C-NMR techniques. Thermal behaviors of polymers and nanocompozits were measured by DSC and TGA, the results revealing were comparized with each others. The values of average molecular weights and polydispersity were measured by GPC. The SEM images were used to investigation morphologies of polymer and nanocomposities. Ratio of nichel metal in the complex produced was estimated by analysis of SEM-EDX of polymer-nichel complex with schiff bases. Magnetization measurements and magnetic suscebtibilities of polymer-nichel complex with schiff bases were recorded. The electrical properties of polymer and nanocompozits were investigated depending on frequency and temperature. The values of dielectric constant, dielectric loss factor, conductivity and suscebtance were plotted, and the results were compared to each others Keywords: MWNT, "Grafting from", ATRP, nanocomposite, dielectric properties, conductivity, SEM, thermal analysis.