The preparation and characterization of phosphorus-terminated poly-1,3-butadiene: new telechelic ionomers

Polybutadienyllithium systems, with high 1,4-microstructure, low polydispersity and M ¯_n in the range (2-10) × 10³, have been produced in hydrocarbon solvents by using n-butyllithium or 3-dimethylamino-propyllithium as initiator. Termination of these 'living' polymers with chlorophosphine, ClPR₂ (R = Ph, Et or Cy), occurs to give oxidatively unstable phosphine derivatives Y-(C₄H₆)_n-PR₂, in up to 93% efficiency. Oxidation products include the related phosphine oxides. Quaternization of the phosphinated polymers in situ with iodomethane gives a quantitative conversion into the cationomeric polymers Y'-(C₄H₆)_n-PR₂Me⁺I^-, including the novel dicationic telechelic systems with Y' = I⁺NMe₃(CH₂)₃, which show thermoplastic elastomeric properties. The products have been characterized by gel permeation chromatography, end-group analysis and ¹H, ¹³C and ³¹P nuclear magnetic resonance spectroscopy. Model quaternary phosphonium derivatives, trans- and cis-t-BuCH₂CHCHCH₂PR₂Me⁺I^- and t-BuCH₂CH(CHCH₂)PR₂Me⁺I^-, are reported and help establish the terminal geometry of the quaternary phosphonium-capped polybutadienes: the addition of phosphorus to the terminal butadienyl follows the order cis-1,4>trans-1,4>1,2 with the amount of 1,2-termination being smallest when R is the bulky cyclohexyl group. © 1990.