Polyesters and Polyarylates

PGS is a bioresorbable elastomeric polymer and extensively evaluated for various biomedical applications such as soft and hard tissue engineering and controlled drug delivery [8]. In a similar way, a number of aliphatic polyester elastomers for various biomedical applications were prepared from diacid monomers such as citric acid and a-ketoglutaric acid with aliphatic diols and triols using thermal polycondensation reactions [9-12]. 

Transesterification between hydroxyl-esters, carboxy-esters, or two ester groups is one of the most important polyesterification technique used for preparing various aliphatic, aliphatic-aromatic or aromatic polyesters (also known as arylates). Titanium alkoxides are very efficient catalysts for transesterification polymerizations, however in some cases it can cause undesirable discoloration to the resulting polymer [15]. A representative example is the synthesis of a polyester based on dimethyl terephthalate using titanium isopropoxide [16] (Fig. 2.3). 

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T. Tokuda, 1. Furukawa, and M. Miyauchi, Substituted phenols as modifiers for aromatic polycarbonate and polycarbonates-polyester and polyarylates, European Patent Application EP 622,393 (1994). 

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