Hexamethylene diamine, poly condensation with

Table 17-6. Dependence of the Intrinsic Viscosity [ry] on the Partition Coefficients PC of Hexamethylene Diamine in the Interfacial Poly condensation with Sebacoyl Dichloride...

When ACPC was condensed with hexamethylene diamine in the presence of two other acid chlorides (seb-acoyl or adipoyl chloride), poly(amide)s 6.6 and 6.10 with various numbers of azo groups per repeating unit (between 0.14 and 1.0, depending on the ratio of the acid chlorides used) could be obtained [35,36]. Thus, block copolymers with a controlled segment length of the poly-(amide) blocks were attainable. 

Investigation of template poly condensation kinetics has only been studied within a very narrow scope. Polymerization of dimethyl tartrate with hexamethylene diamine was found to be enhanced by using as a template poly(vinyl pyrrolidone), poly(2-vinyl pyridine), or polysaccharides and poly(vinyl alcohol), poly(4-vinyl pyridine). In this case, the template can be treated as a catalyst. No information exists on the influence of the template on the order of reaction. The increase in molecular weight of the polymerization product by the template can be induced by a shift of equilibrium or by an increase in the reaction rate. A similar increase in the reaction rate was observed when poly(4-vi-nyl pyridine) was used in the synthesis of poly(terephtalamides) activated by triphenyl phosphite.The authors suggested that a high molecular weight template was involved in the increase of the local concentration of the substrate (terephthalic acid) by adsorption and activation via N-phosphonium salt of poly(4- vinyl pyridine). 

The necessary functional group equivalence required for the poly condensation is achieved by first producing the salt from molar equivalents of the diamine and dicarboxylic acid. For example, adipic acid and hexamethylene diamine form what is known as the AH salt. The purified salt is directly used in the melt polycondensation. The amidation equilibrium is so favorable that the polycondensation can take place in the presence of water, which is therefore used as a heat sink. A typical industrial synthesis is, for example, the polycondensation of the AH salt a 60%-80% sludge of the salt is precondensed with a little acetic acid as regulator (see also Section 28.2.3.2) at 275-280° C for 1-2 hr at 13-17 bar, that is, at the vapor pressure of the steam produced. After a yield of 80%-90% has been reached, further condensation takes place above the melting temperature of 264° C under vacuum. 

Since most (though not all) of the step polymerization processes involve poly condensation (repeated condensation) reactions, the terms step polymerization and condensation polymerization are often used synonymously. Consider, for example, the synthesis of a polyamide, i.e., a polymer with amide (-CONH-) as the characteristic linkage. If we start with, say, hexamethylene-diamine and adipic acid as reactants, the rst step in the formation of the polymer (nylon) is the following reaction producing a monoamide ... 

Polyamides derived from the condensation of cinnamic acid photodimers with aliphatic diamines such as poly(hexamethylene-a-truxillamide) (4.67) are highly photodegradable, photochromic materials. 

Naming of condensation polymers is done as follows. The polymer obtained from reaction (1.3.6) is called poly (ethylene terephthalate) because the repeat unit is the ester of ethylene glycol and terephthalic acid. Similarly, the polymer in Eq. (1.3.7b) is called poly(ft)-aminocaproic acid). The product in Eq. (1.3.7a) is called poly(hexamethylene adipamide), in which the hexamethylene part of the name is associated with the diamine reactant, and the adipamide part is associated with the amide unit in the backbone. 

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