Cyclopolymerization-derived block-copolymers of 4,4-bis(octyloxymethyl)-1,6-heptadiyne with 4,4-dipropargyl malonodinitrile for use in photovoltaics

Abstract

The synthesis of AB-type block copolymers of 4,4-bis(octyloxymethyl)-1,6-heptadiyne (M1) and dipropargyl malonodinitrile (M2) via metathesis-based cyclopolymerization using well-defined molybdenum- and ruthenium-based initiators is described. While backbiting reactions were observed in the case where polymerizations were triggered by [Ru(NCO)₂(IMesH₂)(CH-2-(2-PrO)–C₆H₄] (I2) and [Ru(NCO)₂(3-Br-Py)₂(IMesH₂)(CHPh)] (I3), (IMesH₂ = 1,3-dimesitylimidazolin-2-ylidene, 3-Br-Py = 3-bromopyridine), the use of RuCl₂(Py)₂(IMesH₂)(CHPh) (I1) in THF allowed for the synthesis of poly(M1) without any backbiting, though with a broad PDI. Block copolymers, i.e. poly(M1)-b-poly(M2), could be prepared in a living manner without any backbiting by the use of the Mo-based Schrock-type initiator Mo(N-2,6-i-Pr₂C₆H₃)(CHCMe₂Ph)(OCH(CH₃)₂)₂ (I4) and THF as solvent. Poly(M1)-b-poly(M2) was characterized by UV and fluorescence spectroscopy and used for the construction of a photovoltaic device.