High temperature pyrolysis studies of poly(phenylene vinylene)s PPVs with lateral substituents poly(ε-caprolactone) (PPV–PCL)
or poly(ε-caprolactone) and alternating Br (PPV–PCL–Br) or polystyrene (PPV–PSt) clearly showed that thermal stability of
both the substituent and PPV were affected by the thermal stability of the other. In all the polymers under investigation,
decomposition started by the degradation of the substituent. The thermal stability of the PPV backbone increased in the order
PPV–PCL–Br < PPV–PCL < PPV–PSt. When the thermal stability of the substituent was significantly lower than that of the PPV
backbone, as in the case of PPV–PCL and PPV–PCL–Br, then the radicals generated at early stages of pyrolysis coupled before
the temperature reached to the values necessary for complete decomposition. This inturn yielded a thermally more stable crosslinked
structure. The increase in thermal stability was greater upon coupling of the radicals generated on the PPV backbone.