Direct synthesis of syndiotactic-rich poly(N-isopropylacrylamide) via radical polymerization of hydrogen-bond-complexed monomer

Radical polymerization of N-isopropylacrylamide (NIPAAm) in toluene was investigated in the presence of hexamethylphosphoramide (HMPA). We succeeded in directly preparing syndiotactic-rich poly(NIPAAm), the syndiotacticity of which (r = 70%) is the highest among those of radically-prepared poly(NIPAAm)s so far reported, by lowering polymerization temperature to –60°C in the presence of a twofold amount of HMPA. The NMR analysis revealed that the induced syndiotactic-specificity was ascribed to 1:1 complex formation between NIPAAm and HMPA. Furthermore, thermodynamic analysis described that the induced syndiotactic-specificity was enthalpically achieved.

© 2005. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/