One-pot Synthesis of Polyamide 12,T-polyamide-6 Block Copolymers
Originally published in Journal of Polymer Science, Part A: Polymer Chemistry, Volume 49, Issue 10, 15 May 2011, Pages 2271-2280
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Polyamide 12,T-polyamide-6 (PA-12,T-PA-6) block copolymers were synthesized by anionic polymerization of caprolactam using a PA-12,T macrocoinitiator (McI). PA-12,T McI and its precursors are soluble in molten caprolactam allowing for both the McI step-growth polymerization and anionic polymerization to be performed in one-pot. It was found that the competing reaction rates of caprolactam ring-opening polymerization and McI transamidation are both deterred by a common ion effect using CaCl2 and soluble materials were obtained using >1 mol % CaCl2. Without CaCl2, the reaction mixture solidifies in less than 30 s and produces crosslinked materials. To understand this effect, PA-12,T McI reactions with caprolactam were performed with 1-10 mol % CaCl2, and polymer structures were characterized using 13C NMR and dilute solution viscometry. These data were then correlated with unique thermal properties and swelling behavior of the block copolymers. © 2011 Wiley Periodicals, Inc.