Formation of polyesters by thermally induced polymerization reactions of molecular solids

The development of solid-state polycondensation reactions, starting in 1857 , is reviewed. In many cases, the elimination of metal halides from halogen ated carboxylates leads to the formation of polyesters, among them polyglyc olide, polylactides, polybutyrates, polymandelide, and poly(hydroxymethyl b enzoates). In some cases, a reaction in the solid state is observed, wherea s in other cases temporary liquefaction occurs. The resulting polymers usua lly have a lower degree of polymerization than the products from solution- or melt-polymerization. In some cases, polymers with a distinct micromorpho logy ((high porosity with pores in the sub-mum range) are obtained and may be of interest for special applications, e.g. in medical technology.