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Miscellaneous Block Copolymers

المؤلف:  A. Ravve

المصدر:  Principles of Polymer Chemistry

الجزء والصفحة:  642

2026-03-01

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Miscellaneous Block Copolymers

Polyamide-polyether block copolymers can be formed by a variety of techniques. One of them consists of initial preparation of amine-terminated polyethers. This can be done by reacting hydroxy terminated polyethers with acrylonitrile and then reducing the nitrile groups to amines [429]:

The products of the reduction condense with carboxylic acid-terminated polyamides to form block copolymers. Another one is to form the polyethers with terminal chloride groups [430]. Hydroxy-group terminated polyethers, for instance, can be converted to halogen-terminated polyethers. The products will react with ammonia and the amine-terminated polymer will react with carboxylic acid terminated polyamides [430]. A British patent describes preparations of block copolymers in two steps. In the first one, two different salts of hexamethylene diamine are formed; one with carboxylic acid-terminated polyoxyethylene and the other one with adipic acid (nylon 6,6 salt). In the second step, the two salts are reacted in the melt. Caprolactam can be used in place of the second salt [431]. Also, a Japanese paper describes formations of block copolymers by reacting polyoxyethylene in melt condensation reactions with caprolactam in the presence of dicarboxylic acids [432]. Polyamide-6 (nylon 6) can form block copolymers with rubber [419] and with poly (dimethyl siloxane) [420]. In the latter case, the polysiloxane forms first by “living” polymerization and is terminated by an acylated caprolactam. The caprolactam portion of the molecule is then polymerized with the aid of lithium caprolactamate:

This diblock copolymer can be melt annealed at ca. 250C. It exhibits superior mechanical properties to nylon 6 homopolymer [420].