Synthesis of poly ether ester block copolymers

Synthesis of poly(ether ester) block copolymers 

Monohydroxybutyl terephthalate, bishydroxybutyl terephthalate, and their mixture are formed. 

During the transesterification, oligomerization is possible. The oligomer content does not increase before BD is removed from the reaction medium. Transesterification, similar to PET and PBT homopolymer synthesis, is carried out in excess of glycol, and the conversion is most often 80-90%. Thus, the reactions are carried out in the low pressure melt polycondensation stage [143-147] and in the post-polycondensation process [112,148-151]. 

The cyclization reaction can be reduced by using salts, such as phosphates, terephthalates, citrates and carbonates. The addition of 0.00115 wt% sodium phosphate or 0.005 wt% potassium terephthalate shortens the polycondensation time and lowers the amount of THE formed [133]. 

It is well known that the reaction temperature for PEE and PBT synthesis is about 250-260 C, but after the reaction temperature reaches 260 C, the cyclization and degradation reactions become considerable. As the synthesis temperature increases, the degree of the polycondensation decreases and the acid group concentration increases [144]. The kinetic polyesterification model and the effect of various physico-chemical factors on the reaction of dicarboxylic acids with glycols are discussed in [134,136,156]. 

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Synthesis of Poly(ether-ester) Block Copolymer... 

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