Synthesis of an ABC Type Triblock Copolymer on MWCNT Surface: Structural, Thermal, Electrical and SEM Characterization

Abstract

Abstract : Multi-walled carbon nanotubes (MWNTs) attached to ethylene glycol (MWNT-OH) were grafted with ring-opening polymerization of e-caprolactone (MWNT-pCL). Initiating sites for atom transfer radical polymerization (ATRP) were formed by end acylation of MWNT-pCLwith α-bromopropionyl bromide. After styrene was polymerized by ATRP on the surface of the macroinitiator (MWNT-pCL-Br) in presence of CuBr/2,2′-bipyridine as catalyst at 110 o C, the triblock copolymer (MWNT-pCL-b-PS-b-pGMA) was prepared by the aid of the same technique using glycidyl methacrylate as monomer, at the same catalyst and temperature conditions, by using the diblock copolymer (MWNT-pCL-b-PS) as macroinitiator. The 1 HNMR studies show that structure in terms of mer number per molecule of the ABC type triblock copolymer is MWNT-p(CL) 6 - b -P(S) 36 - b -p(GMA) 1080 . The determination of chemical structure of the triblock copolymer was carried out using Fourier transform infrared (FT-IR), proton nuclear magnetic resonance ( 1 H NMR) and scanning electron microscopy (SEM). Thermal properties were investigated by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The Tg value estimated from the temperature dependence of the dielectric constant, the dielectric loss factor, and the ac conductivity for the triblock copolymer, is in agreement with the DSC value. The results of the dielectric constant and ac conductivity of the triblock copolymer were also discussed.