Synthesis and solubility of the poly(sulfobetaine)s and the corresponding cationic polymers: 1. Synthesis and characterization of sulfobetaines and the corresponding cationic monomers by nuclear magnetic resonance spectra

Sulfobetaines of two types and the corresponding cationic monomers were synthesized; the preparation of their polymers is described. The solubilities and moisture regain properties of the poly(sulfobetaine)s and cationic polymers were investigated in relation to their molecular structures. It was very difficult to distinguish in 1H nuclear magnetic resonance (n.m.r.) and 13C n.m.r. spectra the chemical shift of the methylene moiety (CH2) in the neighbourhood of the quaternary ammonium group. By comparison of the chemical shifts of the corresponding cationic monomers and sulfobetaines in both 1H and 13C n.m.r. spectra, the respective methylene groups were clearly distinguished from their chemical shifts in the 1H and 13C n.m.r. spectra; the conformations of sulfobetaines and the form of cationic monomers in aqueous solution were identified.