Azopolymers, aromatic

In the last few years, the catalyzed oxidative coupling of primary aromatic diamines has been investigated extensively in our laboratories (1, 2, 3) and also by Kotlyarevskii (19, 20, 30). Results of these investigations are reviewed in this chapter as well as the properties of the class of aromatic azopolymers. 

In studying this novel oxidative polymerization we investigated the following points in particular (a) scope of the reaction, (b) side reactions, (c) catalysis, (d) molecular weights obtainable, (e) properties of aromatic azopolymers in bulk and fabricated form. 

Aromatic Azopolymers. Through the described catalyzed oxidative coupling of primary aromatic diamines a great variety of aromatic azopolymers has become easily accessible. Therefore, an investigation of their properties in bulk as well as fabricated form seemed warranted. 

Color. All aromatic azopolymers are colored owing to the strongly chromophoric azogroup. Even the azoblock copolymer derived from a phenyl oxide-isophthalamide backbone (discussed earlier) which has only one azogroup per repeat unit of a molecular weight of 3500 is bright yellow. Naturally, the shade of color of individual polymers depends on the structure of the repeat unit as expected, fully conjugated polymers... 

Fully aromatic azopolymers described show no melting or softening up to the temperature of thermal degradation. Therefore, films and fibers must be prepared from solution films cast are strong, tough and flexible. 

Fiber Properties. One of the polymers, the poly(isophthalamide) of 4,4 -diaminoazobenzene (IV), was selected for investigation of fiber properties of aromatic azopolymers. Table III shows standard tensile data of the "as spun as well as the hot-drawn (1.5X, 350°C.) fiber. As shown, this polymer has tensile properties fairly typical of an aromatic polyamide. 

In view of the good stability of aromatic azopolymers at elevated temperatures, it is not surprising to find a fair retention of tensile properties up to about 400°C. (Table IV). 

Polymerization of Primary Aromatic Diamines to Azopolymers by Oxidative Coupling... 

Side reactions in the oxidative coupling of primary aromatic diamines to azopolymers could severely limit the molecular weights of polymers obtainable and disrupt their ordered, linear structure. To investigate this point the following polymer... 

In the oxidative coupling of primary aromatic diamines to azopolymers cupric ion/nitrogen base complexes serve as homogeneous catalysts. Such complexes are best prepared in situ by oxygenating a cuprous species, preferably CuCl or Cu O/HCl, in the presence of the nitrogen base. Cupric salts investigated except for cupric acetate yielded inactive species. 

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