Synthesis and optical investigation of amphiphilic diblock copolymers containing regioregular poly(3-hexylthiophene) via post-polymerization modification

• P3HT containing rod-coil diblock copolymers were synthesized and characterized.
• Sulfonation or quaternization of the coil block resulted in amphiphilic copolymers.
• Introduction of ionic coil blocks improved the surface wettability of P3HT.

This paper reports on the synthesis and properties of amphiphilic diblock copolymers composed of a regioregular poly(3-hexylthiophene) (P3HT) block and a block of poly(N,N-dimethylamino-2-ethyl methacrylate-random-2-hydroxyethyl methacrylate) (P(DMAEMA-r-HEMA)). Well-defined rod-coil P3HT-b-P(DMAEMA-r-HEMA)) diblock copolymers were synthesized via the combination of quasi-living Grignard metathesis (GRIM) polymerization, end group modification, atom transfer radical polymerization (ATRP), and post-polymerization modification of diblock copolymer precursors and exhibited an average molecular weight of around 11,000 g/mol with low polydispersities below 1.5. The P3HT-b-P(DMAEMA-r-HEMA)) diblock copolymers were easily converted to amphiphilic diblock copolymers due to esterification of HEMA hydroxyl groups and amine quaternization of DMAEMA units to yield anionic or cationic amphiphilic diblock copolymers, respectively. The structure and properties of the resulting diblock copolymers were characterized by proton nuclear magnetic resonance (1H NMR), gel permeation chromatography, Fourier transform infrared, UV–vis spectroscopy, and differential scanning calorimetry.

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