Importance

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Abstract

This invention concerns ortho ester polymers having repeating mer units represented by the general formulas: ##STR1## The polymers are formed by a condensation reaction between ketene acetals having a functionality of two or more and hydroxyl containing compounds having a functionality of two or more. Unlike most conventional condensation reactions, the reaction between a ketene acetal and an alcohol proceeds without the evolution of small molecule by-products which must be removed by distillation in order to achieve high molecular weight. Hence, this new process produces high molecular weight poly (ortho esters) in short reaction times, at essentially room temperature and at atmospheric pressure. Furthermore, linear thermoplastic materials are produced when both the ketene acetal and alcohol have functionalities of two; and because no volatile materials are produced, void free, thermoset materials are produced when either or both the alcohol and ketene acetal have functionalities greater than two and crosslinking occurs. The polymers are bioerodible and are useful in the fabrication of devices and coatings for delivering beneficial agents.

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First Claim