| Conjugated block copolymers offer opportunities for creating new tunable and responsive materials owing to their excellent optical and transport properties. Here, we synthesized a novel amphiphilic block copolymer composed of a widely used hydrophobic conjugated polymer, poly(3-hexylthiophene), and a hydrophilic polymer, poly(triethyl glycol allene) (P3HT-b-PTA), in one pot using nickel complex as a single catalyst via distinct polymerization mechanisms. Because of the hydrophilicity of the PTA segment and its polymer-solvent interaction and hydrophobic/hydrophilic balance of the polymer in water, the P3HT-b-PTA diblock copolymers exhibit excellent thermoresponsive properties in water, and the lower critical solution temperature (LCST) is dependent on polymer concentration and the block ratio. Moreover, conjugated polymers exhibit complicated optical properties dependent on their nano-meter scale morphology. Probably, the amphiphilic rod-coil block copolymer self-assembled into micellar supramolecular structures and the change in effective π-conjugated length of some conjugated P3HT strand of the block copolymer in the selective solvents, both P3HT-b-PTA and P3HT-b-PTA-b-P3HT block copolymers exhibit solvatochromism properties. The emission of the block copolymers can be facilely tuned through variation on solvents with the emission color spanned widely from red to blue. Very interestingly, white-light emission can be readily achieved from the P3HT-b-PTA-b-P3HT triblock copolymer in the mixture of THF and methanol with 1/3 volume ratio. Finally, owing to the interaction of the P3HT with the added protons, the diblock copolymers showed pH-responsive properties in CHCl3 with the emission color shuttled between orange and deep green upon the alternate additions of trifluoroacetic acid and trimethylamine. |
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