1.1. Polyesters Polyesters are the polymers that contain ester functional group in their main chain. The polyesters can be classified according to the composition of their main chain as aliphatic and semi-aromatic in addition to aromatic polyesters. Also can be thermoplastic or perhaps thermoses. All common polyesters are thermoplastics (Rosato, L. et al. 2004).According to the composition of their main chain; polyesters can be classified as shown in table 1. 1.1. 1. Aliphatic polyesters Aliphatic polyesters are the most widely biodegradable polymers that used in environmental and biomedical fields. In general, these polymers are synthesized via chemical polycondensation reactions using catalyst such as titanium oxides (Gross R.A et.al. 2010; Yang et al., 2012).A wide range of aliphatic polyesters can be designed by using various reactants and changing the synthesis conditions to meet specific requirements such as hydrophobicity, crystallinity, solubility, degradability, glass transition temperature, melting temperature and so on (Clarinval A-N., 2005). 1.1.2. Aliphatic polyesters synthesis Polyesters were historically the first family of synthetic condensation polymers and were investigated as part of Carothers’ pioneering …show more content…
et al., 2002) the key strategy to synthesize well-defined block copolymers. Anionic polymerization is characterized by having less termination and chain transfer reactions, carbanions (or, generally speaking, anionic sites) remain active after complete use of monomer, giving the possibility of block copolymer formation, within the simplest case, by introduction of your second monomer in the polymerization mixture giving potential for the preparation of linear block copolymers. For examples, AB diblock copolymers of styrene and isoprene or butadiene, with predictable composition and molecular weights in addition to narrow molecular weight have been synthesized by sequential addition of