Soluble cyclopentadienylated polymers

Abstract

AbstractCopolymers from styrene and a mixture of p‐ and m‐chloromethylstyrene were reacted with sodium cyclopentadienide in THF and precipitated in methanol at temperatures lower than −20°C to obtain soluble cyclopentadienylated polymers. Due to extensive gelation, the content of cyclopentadienyl groups could not be increased to more than 4 mol‐% except with extremely low molecular weight polymers. An improved method, in which the copolymer was cyclopentadienylated in the presence of metallic sodium, gave soluble polymers with up to 29 mol‐% cyclopentadienyl groups. Pendant cyclopentadienyl groups undergo Diels‐Alder/retro‐Diels‐Alder addition to give thermoreversible cross‐linked polymers. The amount of gel fraction of a 4 mol‐% cyclopentadienylated polymer as a function of the heating time was examined in the temperature range of 40–80°C. The DSC curve of a 29 mol‐% cyclopentadienylated polymer showed an exothermic peak due to the Diels‐Alder reaction and an endothermic peak starting around 390°C, a temperature higher than that found for the degradation of polystyrene.