Substituent-induced delocalization effects on hydrogen-bonding interaction in poly( N-phenyl methacrylamide) derivatives

Abstract

Within small molecules, the hydrogen-bonding behaviors affected by delocalization have been studied thoroughly, but rare publication in macromolecules. Therefore, three poly( N-phenyl methacrylamide)s, poly( N-phenyl methacrylamide) (PNPAA), poly( N-4-methoxyphenyl methacrylamide) (PMPMA) and poly( N-4-bromophenyl methacrylamide) (PBPMA), with different inductive substitution at para position of benzene ring are prepared to investigate the substituent-induced delocalization effects on the hydrogen-bonding interaction behaviors. In this study, the variable-temperature FTIR spectrum is used as tool to study the self- and inter-association hydrogen-bonding interaction. FTIR analyses could provide evidences that there is relatively stronger inter-associative hydrogen bonding in poly( N-4-bromophenyl methacrylamide)/P4VP blends. High resolution 13C CP/MAS solid-state NMR analyses indicate that the spin-lattice relaxation time ( T 1 ρ H ) in all PBPMA blends are homogeneous on the scale at which spin-diffusion occurs within the time T 1 ρ H , also due to the enhancement by substituent inductive delocalization.