Synchrotron radiation ablation of polymers having double bonds in their main chains

Polyacetylene (PA), poly(cis- and trans-1,4-butadiene)s (cis- and trans-PBs), and poly(p-phenylene vinylene) (PPV) were ablated by synchrotron radiation (SR), aiming to deposit thin, uniform films of each on a substrate. When PA was irradiated by SR, gaseous phenyl compounds were produced, and a thin amorphous film was deposited on the substrate, exhibiting no characteristics of PA. In the cases of PPV and trans-PB, the source materials were reproduced in the form of thin film on the substrate by SR ablation. When alkali halides, e.g. NaCl and KBr, were used as deposition substrates, PPV was deposited, in an ordered way, on their cleavage surfaces. However, the deposited film of trans-PB by SR ablation was non-crystalline, because it was produced as a copolymer by 1,4- and 1,2-addition polymerizations of ablated butadiene-based fragments. In comparison, thin films of these polymers were also prepared by thermally evaporating them in a vacuum. When trans-PB and PPV were thermally evaporated, thin films with chemically and structurally identical features to the source polymers were produced, respectively. In contrast, a deposited film from cis-PB by SR ablation consisted of carbon compounds, showing no sign of hydrocarbon compounds in it, while trans-PB was produced from cis-PB by thermal vapor deposition.