Monsanto Company

Fred E Strauser

Mark D Paster

A John Solodar

Devdatt L Kurdikar

Jawed Asrar

Polyhydroxyalkanoate (PHA) polyester is extracted from biomass by dissolving the PHA in a non-halogenated solvent which comprises a PHA-poor solvent that dissolves less than 1% of the PHA at temperatures less than the solvent boiling point, or a mixture of a PHA-poor solvent and a PHA-good solvent. Following extraction of PHA under pressure at a temperature above about 80.degree. C., typically above the boiling point of the PHA-poor solvent, PHA polymer is precipitated by cooling the PHA-enriched solvent mixture. Suitable PHA-poor solvents can include linear and branched R.sub.1 --OH alcohols and R.sub.2 --COOR.sub.3 esters where R.sub.1 =C.sub.1 -C.sub.4, R.sub.2 =H, C.sub.1,C.sub.2, or C.sub.3, and R.sub.3 =C.sub.1 -C.sub.5.

High temperature PHA extraction using PHA-poor solvents

Polyhydroxyalkanoate (PHA) polyester is extracted from biomass by dissolving the PHA in a non-halogenated solvent which comprises a PHA-good solvent or a mixture thereof. Suitable PHA-good solvents can be selected from the disclosed alcohols, esters, amides and ketones. The PHA can be recovered, for example, by cooling, by solvent evaporation, or by addition of a PHA-poor solvent, wherein the PHA-poor solvent preferably dissolves less than about 1% (w/v) of the PHA at a temperature below the solvent boiling point. Preferred PHA types for use in the invention are poly (hydroxybutyrate-co-hydroxyvalerate), poly(3-hydroxybutyrate-co-4-hydroxybutyrate), and polymers/copolymers of hydroxyterminated polyhydroxybutyrate.

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St. Charles, MO, United States of America

Fred E Strauser