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Abstract

The present invention is a method of making acrylonitrile copolymers having multi block structure comprising acrylic acid, acryl amids and acrylamidine hydrophilic groups in hydrophilic blocks and residual nitrile groups in hydrophobic blocks, by partial hydrolysis of polyacrylonitrile to a predetermined hydrolysis conversion at which the hydrolysis is self terminating by a process that improves quality and reduces product heterogeneity. It includes forming a first reaction mixture which includes polyacrylonitrile dissolved in an aqueous reactive solvent containing sodium thiocyanate; forming a second reaction mixture comprising a reaction catalyst of the general formula MY dissolved in an aqueous reactive solvent containing sodium thiocyanate; mixing the reaction mixtures of steps (a) and (b) above to form a master reaction mix; dividing the reaction mix into a plurality of physical reaction compartments so as to increase outer surface area relative to volume as compared to outer surface area of a single reaction compartment to enhance cooling efficiency and to reduce undesirable center core thermal effects; and, heating the divided master reaction mix to a predetermined reaction temperature range and maintaining the temperature range for a predetermined time sufficient for completion of a predetermined level of hydrolysis at which the resulting copolymer solution is substantially stable at ambient temperature. The invention also includes hydrogel products resulting from the method.

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First Claim