Long Chain Polyhydroxyacid

Another new family of biodegradable polyesters containing a hydroxyacid repetitive unit is that of the long chain polyhydroxyacid or polyhydroxyfattyacid. 

These products, even though from a chemistry point of view can be considered of the PHA family (Section 10.2.1.2), due to their physico-chemical properties and polymer synthesis, have been classified separately. 

Thanks to genetic science, engineered yeasts strain, such as Candida tropicalis, can lead to the production of co-hydroxyfattyacid or a,(0-dicarboxylic acid containing 12-22 carbon atoms from renewable resources (i.e., natural oils) via fermentation processes. These fermentation processes avoid the poor yields and extensive purification required by chemical conversion [29]. 

Unlike PHA, where microbial activity gives rise to the final polymers, the fermentation process used for co-hydroxyfattyacid leads to monomers which can be copolymerised with a wide range of other monomers to manufacture polymers with different final properties. 

The polymer synthesis of long chain polyhydroxyacids can be performed either in bulk via condensation reactions or by the ring-opening polymerisation of lactones/ macrolactones obtained by co-hydroxyfattyacid cyclisation [30]. 

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