Novel synthesis of N‐substituted polyacrylamides: Derivatization of poly(acrylic acid) with amines using a triazine‐based condensing reagent

Poly(acrylic acid) (PAA) was derivatized through the reaction of its pendant carboxylic acid (CO2H) groups with a wide range of amine‐terminated molecules. These molecules contained alkyl, hydroxyl, sulfonic acid, or perfluoroalkyl groups. N‐substitution of PAA was carried out by the simple addition of 4‐(4,6‐dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium chloride (DMTMM), a triazine‐based condensing reagent, to a mixture of PAA and amine‐terminated molecules. From proton nuclear magnetic resonance and infrared spectroscopy, it was confirmed that these functional molecules were introduced into the PAA side chain via amide bonds. By the alteration of the synthetic conditions, functional side‐chain contents of greater than 95% were achieved for aqueous reactions with taurine, ethanol amine, and butyl amine. Side‐chain conversion was limited to ≤80% for reactions with perfluoroalkyl amines in methanol. Thus, DMTMM is an attractive replacement for carbodiimide condensing reagents such as 1,3‐dicyclohexylcarbodiimide and 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide.