Facile Preparation Of Regioregular Poly(3-hexylthiophene) And Its Block Copolymers With π-Allylnickel Complex

Widespread attention and interest has been paid on conjugated polymers due to their potential for applications in optoelectronic and electrochemical devices, such as photovoltaic cells, chemosensors, and field-effect transistors. Poly(3-hexylthiophene) (P3HT) and its derivatives, which fall into this category of π-conjugated polymers above-mentioned,have been widely studied by virtue of their excellent properties and easy preparation.In this paper, we used π-allylnickel complexes which were simply prepared as external initiators for promoting the polymerization of 2-bromo-3-hexyl-5-megnusimthiophene to gain regioregular P3HT with an allyl terminus. This polymerization reaction was in a living/controlled chain growth manner. Using the Ni(II)-terminated P3HT as a catalyst, we obtained P3HT-b-poly(hexadecyloxylallene)(PHA) diblock copolymers and well-defined P3HT-b-PHA-b-P3HT triblock copolymers by mechanically distinct, sequential living polymerization in one pot. Meanwhile, such π-allylnickel(Ⅱ) complexes can also be applied to initiate the polymerization of some vinyl monomers, including styrene,1-chloro-4-vinylbenzene,1-methoxy-4-vinylbenzene and t-butyl acrylate, in a living/controlled chain growth manner. Furthermore, the active nickel species on the chain end of these vinyl polymers can catalyze the block copolymerization reaction of 2-bromo-3-hexyl-5-megnusimthiophene to afford a series of block copolymers which contain vinyl homopolymer and P3HT segments.These reactions are performed in living/controlled fashion. As required,we use size exclusion chromatography (SEC) to monitor the process of these reactions,1H NMR, MALDI-TOF,31P NMR and IR. and so on to make characterization of the polymers and copolymers. By controling the feed ratio of monomer to macroinitiator, all the block copolymers above-mentioned are isolated with controlled molecular weight and tunable compositions.