| abstract |
Process for preparing a polyhydroxyalkanoate (PHA) polymer by ring-opening polymerization of a lactone such as -butyrolactone, preferably racemic, in which the polymerization is carried out in the presence of an initiator of formula (II): R<SUP>2</SUP> R<SUP>2</SUP> N THF R<SUP>1</SUP> OMO R<SUP>1</SUP> OX R<SUP>3</SUP> in which: - R<SUP>3</SUP> represents a C<SUB>1</SUB> to C<SUB>15</SUB> alkyl group such as a methyl, ethyl, i-propyl, n-propyl, 15-n-butyl, i-butyl or tert-butyl group; a benzyl group; an R<SUB>2</SUB>,<SUB/>which may be identical or different, - R<SUB>1</SUB> each represent a group chosen from C<SUB>1</SUB> to C<SUB>15</SUB> alkyl groups, such as methyl or tert-butyl; cumyl; (Q,Q-dimethylbenzyl); adamantyl; trityl; and trialkylsilyl; - X represents O(R<SUB>4</SUB>), S(R<SUB>4</SUB>) or N(R<SUB>4</SUB>)(R<SUB>5</SUB>) where R<SUB>4</SUB> and R<SUB>5</SUB> each independently represent a C<SUB>1</SUB> to C<SUB>15</SUB> alkyl group such as a methyl or ethyl group; or a benzyl group, - M is a metal of group 3 of the Periodic Table of Elements, such as Y, La or Nd. Polymers which can be obtained by means of this process, compositions using them and use of these polymers and compositions. |