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Abstract
A polymerization technique that allows control of molecular weight has been successfully applied in the synthesis of poly(2-dimethyloctylsilyl)-phenylenevinylene (DMOS-PPV). The technique consists of addition of the monomer to a large excess of base in the presence of an anionic initiator. The anionic polymerization technique was also used to obtain block copolymers of MEH-PPV and DMOS-PPV for the first time. A series of triblock and star copolymers of DMOS-PPV with poly (MEH-PPV) were also synthesized using difunctional and trifunctional initiators. The synthesized homopolymers and copolymers had high molecular weights (>105), displayed very narrow molecular weight distributions (≤1.2), and were obtained by a single precipitation of the reaction mixture into methanol and water. No fractionation was necessary to achieve the low polydispersity values reported. Gel permeation chromatography (GPC) revealed that the homopolymers and copolymers obtained using phloroglucinol as the initiator contained three arms, which confirmed their star-shaped structures. The copolymers were further characterized by their absorption and emission spectra, and their compositions, which reflected the feedstock ratio, were determined by 1H-NMR. Additionally, the polymers contained <1% defects arising from head-to-head (H-H) coupling.
