ma990825x_si_001.pdf (20 kB)
Synthesis of Substituted Poly(p-phenylenevinylene) Copolymers by the Heck Method for Luminescence Studies
journal contribution
posted on 1999-09-24, 00:00 authored by Susan T. Pasco, Paul M. Lahti, Frank E. KaraszHeck carbon−carbon bond-forming polymerization was used to make segmented copolymers
based on poly[1,8-octanedioxy-1,4-phenylene-1,2-ethenylene-1,4-phenylene-1,2-ethenylene-1,4-phenylene].
The Heck methodology yielded copolymers with molecular weights, polydispersities, and optical properties
that are comparable to or better than those previously obtained for the same or very closely related
polymers obtained by Wittig methodology. However, it proved important to have methoxy groups
incorporated into the chromophore of the copolymers to get high yields of material with good degrees of
polymerization. The obtained yields and purities for the Heck-derived polymers are better, in part due to
the direct formation of desirable trans olefin linkages in the polyphenylenevinylene type chromophore
units. Differential scanning calorimetric measurements show that placement of isopropyl groups on the
central ring of the chromophoric fragment does not alter the polymer glass transition temperature relative
to an unsubstituted copolymer but that placement of n-hexyl groups lowers the glass transition
substantially. The decrease in Tg is attributable to copolymer self-plasticization by the n-hexyl groups.