Polybenzoxazole via aromatic nucleophilic displacement

US5270432A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Paul M. Hergenrother · Yorktown, US
• John W. Connell · Newport News, US
• Joseph G. Smith, Jr. · Smithfield, US

Key dates

• Filing date: Apr 10, 1992
• Grant date: Dec 14, 1993
• Expiry date: Apr 10, 2012

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G73/22
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Polybenzoxazoles (PBO) are prepared by the aromatic nucleophilic displacement reaction of novel di(hydroxyphenyl)benzoxazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations are carried out in polar aprotic solvents, such as N-methylpyrrolidine or N,N-dimethylacetamide, using alkali metal bases, such as potassium carbonate, at elevated temperatures under nitrogen. The novel di(hydroxyphenyl)benzoxazole monomers are synthesized by reacting phenyl-4-hydroxybenzoate with aromatic bis(o-aminophenol)s in the melt. High molecular weight PBO of new chemical structures are prepared that exhibit a favorable combination of physical and mechanical properties. The use of the novel di(hydroxyphenyl)benzoxazoles permits a more economical and easier way to prepare PBO than previous routes.