Cyclic polycarbonate oligomers from spirobiindane bisphenols

Abstract

Cyclic polycarbonate mixtures containing units derived from spirobiindane bisphenols, preferably 6,6'-dihydroxy-3,3,3',3'-tetramethylspirobiindane, are prepared from the corresponding bischloroformates or mixtures thereof with bisphenols. They may be homopolymeric or copolymeric; cyclic oligomer mixtures are preferred. Such oligomers may be converted to linear polycarbonates having high glass transition temperatures.

Dependencies are inferred from the claim text.