Polymerization, interfacial polyester production

Using the much more reactive acid chloride monomer allows polyester production at much lower temperatures than when using the ester, or free acid. Even under ambient conditions it is so vigorous that interfacial polymerization of diluted solutions of the monomers in an appropriate, immiscible solvent pair may be needed to control the rate. However, the high cost of the acid chloride as compared to terephthalic acid or the ester makes this route commercially unattractive. Also with this monomer pair the kinetic treatment and molecular weight distributions will differ from the general cases outlined in Chapter 20. 

Polyesters were historically the first synthetic condensation polymers studied by Carothers in his pioneering work in the early 1930s. Commercial polyesters [30] were manufactured by polycondensation reactions, the methods commonly used being melt polymerization of diacid and diol, ester interchange of diester and diol, and interfacial polymerization (Schotten-Baumann reaction) of diacid chloride and diol. In a polycondensation reaction a by-product is generated which has to be removed as the reaction progresses. 

The polymerization step is chosen appropriate to the monomers used and products produced. Solution pol3nnerization, interfacial condensation, and ester interchange can be used to produce polyesters for example. References 27 and 29 should be consulted to locate specific reaction conditions and methods for a given polymer class. 

Carraher recently reviewed these s3mtheses, emphasizing polymerizations employing the interfacial condensation technique. For the synthesis of poly-phosphonate and polyphosphate esters and amides Carraher, Millich and others have reported that hydrolysis of the acid chloride typically limits the product yield and molecular weight.The synthesis of polyesters ... 

Germanium polyesters, 74, were reported by Carraher and Dammeier " in 1971. The materials were made by a classical interfacial polycondensation process where salts of the dicarboxylic acids are dissolved in water and the organic phase contains diorganogermanimn dihalides. The products are formed within seconds in 10-50% yield and have a MW of 2000-3000, which represents a number average degree of polymerization of 7-12 (Scheme 25). 

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