Block sequence dependent self-assembly and optoelectronic behavior of thermo- and pH-sensitive Polythiophene-graft-[Poly(diethylene glycol methyl ether methacrylate)-block-Poly(dimethyl amino ethyl methacrylate)] copolymers

Abstract

To overcome the difficulty of using multistep process we report an one pot synthesis of polythiophene (PT)-graft block copolymers with thermo-sensitive poly(diethyleneglycol methyl ether methacrylate)(PDEGMEM) and pH-sensitive poly(dimethyl amino ethyl methacrylate)(PDMAEMA) using ATRP technique. The polymers PT-g-(PDEGMEM10-b-PDMAEMA3) (P1), PT-g-(PDMAEMA10-b-PDEGMEM3) (P2) and PT-g-(PDMAEMA6-ran-PDEGMEM8) (P3) are characterized by 1H NMR and SEC techniques. HRTEM study shows that P1 and P3 exhibit micellar morphology but P2 shows vesicular morphology, all sizes increase with increasing pH and temperature. UV–vis absorption spectra show pH, temperature and sequence dependent absorbance peak, and dc-conductivity (P2 > P3 > P1) indicates semi-conducting nature. Current-Voltage (I-V) property shows pH dependent memory and OMEIC property following above order. At pH3, on irradiation with white light the photocurrent gains of P2, P3 and P1 are 7.9, 6.6 and 3.5, respectively. Thus PT-graft block copolymers exhibit tunable self-assembly, optoelectronic, transport and photocurrent properties depending on proximity and preponderance of block sequence from PT backbone and also for their pH and thermo-responsivity.