SYNTHESIS AND PROPERTIES OF POLY(P-PHENYLENE OCTYLENE)

Acyclic diene metathesis (ADMET) polymerization was used as a new synt hetic route to a class of processable, hydrophobic, and crystalline po lymers which contain only aromatic and aliphatic hydrocarbon units in their backbone. Poly(p-phenylene octylene) (PPPO), as a first example, was prepared by the ADMET polymerization of 1,4-bis(pent-4-ene)benzen e, followed by the catalytic reduction of the resulting unsaturated po lymer. The weight-average molecular weights of the polymers obtained w ith this method were in the range of 13 000-25 000. Poly(p-phenylene o ctylene) was found to be highly soluble in common solvents and to have a melting temperature of around 90 degrees C, which enabled melt proc essing into fibers and films without decomposition. Wide-angle X-ray d iffraction and annealing experiments on PPPO revealed two different cr ystal modifications. The polymer, as precipitated from the reaction mi xture, predominantly forms the kinetically preferred modification alph a, while the annealing of pristine PPPO almost exclusively leads to th e thermodynamically more stable modification beta.