Polyhydroxyalkanoate block copolymer and method for preparing the same
A polyhydroxyalkanoate block copolymer includes a first segment containing a first monomeric unit represented by formula (I); and a second segment containing the first monomeric unit represented by formula (I), a second monomeric unit represented by formula (II), and a third monomeric unit represented by formula (III), The first segment and the second segment are arranged in blocks. A method for preparing the polyhydroxyalkanoate block copolymer is also disclosed.
1 . A polyhydroxyalkanoate block copolymer, comprising:
a first segment containing a first monomeric unit represented by formula (I); and
a second segment containing the first monomeric unit represented by formula (I), a second monomeric unit represented by formula (II), and a third monomeric unit represented by formula (III),
wherein the first segment and the second segment are arranged in blocks.
2 . The polyhydroxyalkanoate block copolymer as claimed in claim 1 , wherein the first monomeric unit, the second monomeric unit, and the third monomeric unit are randomly arranged in the second segment.
3 . The polyhydroxyalkanoate block copolymer as claimed in claim 1 , wherein based on the total amount of the first segment and the second segment as 100 mol %, the second monomeric unit is present in an amount ranging from 15 mol % to 50 mol %, the third monomeric unit is present in an amount ranging from 0.3 mol % to 6.0 mol %, and a balance being an amount of the first monomeric unit.
4 . A method for preparing a polyhydroxyalkanoate block copolymer, comprising the steps of:
(a) cultivating Cupriavidus necator H16 in a liquid medium containing gluconic acid, followed by conducting a first fermentation process to obtain a fermented culture,
wherein the gluconic acid is completely consumed by Cupriavidus necator H16, so that a first segment containing a first monomeric unit represented by formula (I) is generated in Cupriavidus necator H16, and the fermented culture is substantially free of the gluconic acid; and
(b) adding levulinic acid to the fermented culture, followed by conducting a second fermentation process, so that the levulinic acid is consumed by Cupriavidus necator H16, followed by generation of a polyhydroxyalkanoate block copolymer including the first segment and a second segment in Cupriavidus necator H16,
wherein the first segment and the second segment are arranged in blocks, and the second segment contains the first monomeric unit represented by formula (I), a second monomeric unit represented by formula (II), and a third monomeric unit represented by formula (III),
5 . The method as claimed in claim 4 , wherein in step (a), the liquid medium contains 0.2% w/v to 0.4% w/v of the gluconic acid.
6 . The method as claimed in claim 4 , wherein in step (b), the fermented culture contains 0.05% w/v to 0.2% w/v of the levulinic acid.
7 . The method as claimed in claim 4 , wherein in step (a), the liquid medium is a mineral salt liquid medium which includes water, Na 2 HPO 4 ·2H 2 O, KH 2 PO 4 , (NH 4 ) 2 SO 4 and MgSO 4 ·7H 2 O.