Synthesis and optical properties of a copolymer of tetrafluoro- and dialkoxy-substituted poly (p-phenylenevinylene) with a high percentage of fluorinated units

A copolymer of 2,3,5,6-tetrafluoro-1,4-phenylenevinylene and 2,5-dioctyloxy-1,4-phenylenevineylene [co(TFPV-DOPV)], containing more than 60% of tetrafluorophenylenevinylene monomeric units, was synthesized by the Stille cross-coupling reaction. Its linear and nonlinear optical properties were investigated. Linear absorption and photoluminescence measurements performed on thin films and solution indicate interchain migration upon excitation. The Z-scan technique was used to evaluate the third-order nonlinear susceptibility at lambda = 1064 nm. A very high refractive nonlinearity (n(2) = (-10 +/- 2) x 10(-12) cm(2) (.) W-1) was measured with a value one order of magnitude larger than that of the corresponding dialkoxy-substituted homopolymer.