PROCESS FOR CONTROLLED DEGRADATION OF POLYHYDROXYALKANOATES AND PRODUCTS OBTAINABLE THEREFROM

摘要

The present invention relates to a process for producing polyhydroxyalkanoate oligomers and/or polymers of reduced molecular weight, which comprises reacting at least one polyhydroxyalkanoate (PHA) with at least one carbonate salt at a temperature of from 50°C to 300°C, preferably from 120°C to 200°C. The above reaction allows a controlled degradation of the PHA chains which yields oligomers and/or polymers having a controlled molecular weight, which can be modulated in view of the specific application for which the oligomers and/or polymers are intended. Moreover, during the reaction carbon dioxide evolves which produces a foamed material which can be easily processed on an industrial scale. Additionally, the above oligomers and/or polymers, having an end-group bearing a double bond C=C, particularly a crotonate end-group for PHB, can be subjected to subsequent modifications to obtain a wide variety of functional end-groups, for instance carboxyl, carboxylate, hydroxyl, dihydroxyl, oxirane ring, halogen atom. Moreover, the low molecular weight PHAs may be used in the area of controlled delivery systems in agro-chemistry, in the cosmetic industry, in medicine in the form of nano- or microspheres, in household products and in coating systems.