Synthesis and self-assembly of water-soluble polythiophene-graft-poly(ethylene oxide) copolymers

Abstract

In this study, we synthesized amphiphilic poly(3-hexylthiophene)-graft-poly(ethylene oxide) (P3HT-g-PEO) rod-coil conjugated random copolymers through oxidative polymerization with FeCl3 and facile click chemistry and characterized them using H-1 nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry (DSC), X-ray photoelectron spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. We then used atomic force microscopy, transmission electron microscopy, and dynamic light scattering to investigate the self-assembled structures formed from these amphiphilic random copolymers in solution and in the bulk state. In the bulk state, DSC analyses revealed that after PEO had been grafted onto P3HT, the crystallization temperature of PEO decreased from +20 to -26 degrees C as a result of hard confinement of microphase separation in the copolymer system. In addition, we found that the amphiphilic conjugated random copolymers could form micelle structures in the DMF-water system.