Structure and properties of p-phenylenevinylene-p-xylylene copolymers prepared by vapor-deposition polymerization

Abstract

Films based on the p phenylenevinylene-p xylylene precursor are prepared via vapor deposition polymerization during the pyrolysis of α, α' dichloro p xylene on a copper grid in vacuum at substrate tem peratures -196, 25, and 50°C. Subsequent annealing of the precursor at 250°C yields the final material: the copolymer of p phenylenevinylene and p xylylene. The structure, surface morphology, and optical properties of the copolymer are studied at different substrate temperatures and copper amounts in the pyrolysis zone. It is found that p phenylenevinylene units mostly occur in trans configurations. The thermal treatment of the precursor is accompanied by an increase in the mean square surface roughness and a decrease in roughness coefficient α from 0.84 ± 0.05 to 0.79 ± 0.05. As the content of copper in the pyrolysis zone increases, the concentration of p xylylene fragments in the copolymer tends to increase; the band gap increases from -2.5 to 3.1 eV. Depending on synthesis conditions, the copolymer is characterized by a shift of the fluorescence spectrum maximum that achieves 150 nm in the visible spectral region.

Functionalization of Poly(para‐xylylene)s—Opportunities and Challenges as Coating Material

“…The pyrolysis of α,α′‐dichloroxylene and a subsequent annealing step also gave PPV‐PPX copolymers. [ 78,79 ] Here the composition of PPX to PPV units was controlled through reaction temperatures and by using a copper substrate that causes an increase in PPX fragments. Trihalogenated p ‐xylenes were also successfully used for the PPX synthesis.…”