Synthesis of New Thermally Stable Halopolyamides

Several new thermally stable halopolyamides were prepared by low temperature solution polycondensation from some new diacid chlorides and a number of diamines, namely p-phenylenediamine (I), m-phenylenediamine (II), benzidine (III), 4,4′-diamino-diphenylmethane (IV), 4,4′-diaminodiphenyl sulfone (V), ethylene-diamine (VI), hexamethylenediamine (VII), and 4,4′-diamino-dicyclohexylmethane (VIII). The diacid chlorides were derived from two series of some new dicarboxylic acids: (A) 2-halo-(chloro-, bromo-, and iodo-)-4-carboxyphenoxyacetic acid (K-XI); and (B) 2-halo-(chloro- and iodo-)hydroquinone-l,4-diacetic acid (XII and XIII). Dimethyl esters and diamide derivatives were prepared to confirm the structures of the diacid chlorides (Ka-XIIIa)i Nylon salts of the new dicarboxylic acids (DC-XIII) were also prepared. Some of the factors affecting the reduced viscosity of the polymers such as the effect of the concentration of initial components, temperature, and duration time were studied. In the case of the polymerization of 2-chloro-4-chlorocarbonylacetyl chloride (DCa) with diamines I and VII as representatives of aromatic and aliphatic diamines, maximum viscosity values were obtained by the use of 0.5 mol/L at −10°C for both diamines, whereas the optimum time was 30 min for diamine VII and 45 min for I. No effect on reduced viscosities was observed with time in the case of reactions carried out at room temperature. The optimum conditions were then applied in the case of the other diacid chlorides (XIa, XIIa, and XIIIa) in order to obtain the corresponding halopolyamides. Study of the thermal stability using DSC showed that the halopolyamides obtained from the more rigid dicarboxylic acids series A have higher T values than those of the less rigid series B which carry more ether units. Halopolyamides derived from aliphatic diamines are less thermally stable than those derived from aromatic diamines. Films could be obtained from halopolyamides via either the solution or melt phase.