Low-temperature processable aliphatic polyester

1. A low-temperature processable aliphatic polyester comprising 3-hydroxybutyrate monomers and 4-hydroxybutyrate monomers as polyhydroxyalkanoate copolymer molecules,

wherein a content of the 4-hydroxybutyrate monomers is 76 to 98 mol %.

2. The low-temperature processable aliphatic polyester according to claim 1 ,

wherein a weight average molecular weight of the copolymer molecules is 200 to 800 kDa.

3. The low-temperature processable aliphatic polyester according to claim 1 ,

wherein the content of the 4-hydroxybutyrate monomers is 85 to 95 mol %.

4. The low-temperature processable aliphatic polyester according to claim 1 ,

having a melting point (Tm) of 30° C. to 100° C. and a decomposition temperature (Td) of 200° C. to 400° C.

5. The low-temperature processable aliphatic polyester according to claim 1 ,

having an acid value of 0.5 to 4.

6. The low-temperature processable aliphatic polyester according to claim 1 ,

having a color difference of b* of 1 to 15.

7. The low-temperature processable aliphatic polyester according to claim 1 ,

having a melt flow index (MFI) of 3 to 10.

8. The low-temperature processable aliphatic polyester according to claim 1 ,

having an elongation of 1000% to 2500%.

9. The low-temperature processable aliphatic polyester according to claim 1 ,

having a tensile strength of 1 MPa to 20 MPa.

10. The low-temperature processable aliphatic polyester according to claim 1 ,

having a refractive index (nD 25 ) of 1.3 to 1.7.

11. A method for preparing a low-temperature processable aliphatic polyester comprising 3-hydroxybutyrate monomers and 4-hydroxybutyrate monomers as polyhydroxyalkanoate copolymer molecules, wherein a content of the 4-hydroxybutyrate monomers is 76 to 98 mol %,

the method comprising the step of: culturing an organism in the presence of one or more carbon raw materials under conditions under which (a) the one or more carbon raw materials are converted to 3-hydroxybutyryl-CoA and 4-hydroxybutyryl-CoA and (b) the 3-hydroxybutyryl-CoA and the 4-hydroxybutyryl-CoA are polymerized to form the polyhydroxyalkanoate copolymer molecules, thereby forming the polyhydroxyalkanoate copolymer molecules.

12. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the organism has been genetically engineered to comprise enzymatic activities of a polyhydroxyalkanoate synthase, an acetyl-CoA acetyltransferase, an acetoacetyl-CoA reductase, a succinate semialdehyde dehydrogenase, a succinic semialdehyde reductase, and a CoA transferase by stable incorporation of genes encoding the polyhydroxyalkanoate synthase, the acetyl-CoA acetyltransferase, the acetoacetyl-CoA reductase, the succinate semialdehyde dehydrogenase, the succinic semialdehyde reductase, and the CoA transferase into the organism by introduction of one or more stable plasmids comprising the genes and/or by integration of the genes into the genome of the organism, and to not comprise enzymatic activities of either an NAD+-dependent succinate-semialdehyde dehydrogenase or an NADP+-dependent succinate-semialdehyde dehydrogenase or both.

13. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the one or more carbon raw materials, taken together, have a biobased content of ≥50%.

14. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the organism has further been genetically engineered (a) to comprise enzymatic activities of (i) an alpha-ketoglutarate decarboxylase or 2-oxoglutarate decarboxylase and (ii) an L-1,2-propanediol oxidoreductase, and (b) to not comprise enzymatic activities of one or more of (i) a thioesterase II, (ii) a multifunctional acyl-CoA thioesterase I and protease I and lysophospholipase L, (iii) an acyl-CoA thioesterase, and (iv) an aldehyde dehydrogenase.

15. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the one or more carbon raw materials comprise a carbon source selected from the group consisting of glucose, levoglucosan, sucrose, lactose, fructose, xylose, maltose, arabinose, and mixtures thereof.

16. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the one or more carbon raw materials comprise one or more of molasses, starch, a fatty acid, a vegetable oil, a lignocellulosic material, ethanol, acetic acid, glycerol, a biomass-derived synthesis gas, and methane originating from a landfill gas.

17. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

wherein the one or more carbon raw materials do not comprise γ-butyrolactone, 1,4-butanediol, 4-hydroxybutyrate, 3-hydroxybutyrate, α-ketoglutarate, oxaloacetate, malate, fumarate, citrate, succinate, or 3-hydroxybutyrate.

18. The method for preparing the low-temperature processable aliphatic polyester according to claim 11 ,

further comprising isolating the polyhydroxyalkanoate copolymer molecules from the organism, such that the polyhydroxyalkanoate copolymer composition is substantially free of the organism.

19. A low-temperature processable aliphatic polyester prepared by the method according to claim 11 .

20. The low-temperature processable aliphatic polyester according to claim 19 ,

wherein the content of the 4-hydroxybutyrate monomers using the fermentation of a strain is 76 to 98 mol %.

21. An article comprising the low-temperature processable aliphatic polyester according to claim 1 ,

wherein the article is a biodegradable wax, a medical device, a low-temperature hot melt, a non-woven cloth, a bioplastic, a drug carrier, a medical wrap, a medical fiber, a medical filament, a medical stent, or an orthopedic prosthesis.