Closed cell foams including poly-4-hydroxybutyrate and copolymers thereof

US11292885B1 · kind B1 · utility

Assignee

• Tepha, Inc. · US

Inventors

• Dennis W. Connelly · Arlington, US
• Fabio Felix · Foxborough, US
• David P. Martin · Arlington, US
• Jon I. Montcrieff · Mansfield, US
• Said Rizk · Windham, US
• Simon F. Williams · Sherborn, US

Key dates

• Filing date: Jun 11, 2020
• Grant date: Apr 5, 2022
• Expiry date: Jun 11, 2040

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08L2205/02
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

Methods to produce substantially closed cell foams with densities less than 0.75 g/cm3, and more preferably less than 0.5 g/cm3, without substantial loss of the polymer's weight average molecular weight, have been developed. The closed cells foams have an open cell content of generally less than 50%, and more preferably an open cell content of less than 20%, and the cells have a maximum diameter of less than 5 mm. The foam may include poly-4-hydroxybutyrate or a copolymer thereof. Preferably, the foam is derived by heating a foam polymer formula to a temperature above the melt temperature of the polymer to form a melt polymer system, adding a blowing agent to produce a foamable melt, extruding the foamable melt through a die to a lower pressure to cause foaming, cooling of the foam, and solidification of the foam. These foam structures can be used for fabrication of medical products.