Novel polyiminocarbonates having molecular weights exceeding 70,000 daltons. Novel solution polymerization and interfacial polymerization processes for the preparation of polyiminocarbonates in which cyanate compounds are reacted with diphenol compounds in the presence of a strong base catalyst.
Novel amino acid-derived polycarbonates and amino acid-derived diphenol compound starting materials from which the polycarbonates are polymerized. Polymer blends of the amino acid-derived polycarbonates with polyiminocarbonates prepared from identical amino acid-derived diphenol starting materials.
Novel polyiminocarbonates having molecular weights exceeding 70,000 daltons. Novel solution polymerization and interfacial polymerization processes for the preparation of polyiminocarbonates in which cyanate compounds are reacted with diphenol compounds in the presence of a strong base catalyst.
Bioerodible polyarylates derived from biocompatible dicarboxylic acids and natural amino acid-derived diphenol starting materials. Molded articles and controlled drug delivery systems prepared from the polyarylates are also disclosed.
Improvements are disclosed for biphasic polymerization processes in which an aqueous solution of a first monomer that is hydrolytically unstable below a pH of about six or above a pH of about eight is admixed with a water-immiscible organic solvent and there is added to the admixture a catalyst selected from tertiary amine, quaternary amine and phosphonium catalysts, an acid-forming co-monomer for the first monomer, an acid scavenger, after which the resulting polymer is recovered, wherein the improvement includes providing the aqueous solution at a pH between about si and about eight, and adding to the admixture the acid-forming co-monomer and the acid scavenger at relative rates effective to maintain the pH of the admixture between about six and about eight. The catalyst may be added in a molar ratio to the first monomer effective to provide a predetermined weight-average or number-average molecular weight for the resulting polymer. Biphasic polymerization processes for monomers that are not pH sensitive are also disclosed.
A process for selectively modifying pendent functionalities of a polymer containing the pendent functionalities and hydrolytically unstable backbone functionalities is provided. The process includes: (a) providing the polymer in a solvent system (preferably an ether-containing solvent system) adapted to maintain the polymer in a dissolved or partially dissolved state, wherein the pendent functionalities of the polymer are more accessible than the hydrolytically unstable backbone functionalities; and (b) adding at least one additive to the solvent system to selectively modify at least one of the pendent functionalities. The process is especially well suited for specifically acid hydrolyzing pendent esters of PDTE.
