Positron annihilation study of polyphenylene dendrimers

The free volume of a series of rigid polyphenylene dendrimers was studied by positron lifetime spectroscopy and the experimental data were compared with results from molecular dynamics calculations. Contrary to dendrimers containing flexible repeat units rigid polyphenylene dendrimers proved to contain large stable "inner" voids of a distinct size between their dendritic branches. The size of the "inner" cavities increases with the size of the dendrimer. Due to these voids, polyphenylene dendrimers are potentially attractive with respect to the selective incorporation of guest molecules. (C) 2003 Published by Elsevier Science Ltd.