Heterogeneous catalytic ring opening polymerization of 2,2-dimethyltrimethylene carbonate with metal alkoxides as initiators in protic conditions

The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) by using new heterogeneous systems as initiators has been investigated. These systems a re obtained by grafting various Lewis acid metal alkoxides belonging to gro up IIb (Zn), IIIa (Al), IIIb (Y and Nd) as well as IVb (Ti and Zr) on porou s solids (silica, alumina and zinc oxide). Adding alcohol in excess to the reaction mixture induces a transfer reaction which allows to synthesise fun ctionalized polycarbonates. In most cases, the degree of polymerization is controlled by the [monomer]/[alcohol] ratio. It was found that the activity depends both on the metal and on the solid support. Y alkoxides offer the best activities while those belonging to group IVb are less efficient. The porous solid acts as a chemical ligand rather than only as a mechanical sup port of the active centres.