Properties of poly[<i>N</i>‐2‐(methyacryloyloxy)ethyl‐<i>N</i>,<i>N</i>‐dimethyl‐<i>N</i>‐3‐sulfopropylammonium betaine] in dilute solution

Abstract

Abstract Poly[ N ‐2‐(methacryloyloxy)ethyl‐ N,N ‐dimethyl‐ N ‐3‐sulfopropylammonium betaine] (1) which is an interesting polyzwitterion polymer by virtue of its “antipolyelectrolyte solution behaviour” has been prepared by free‐radical initiated polymerization in aqueous solution. Isothermal fractionation was conducted at 294 K employing formamide as solvent and acetone as precipitant. Twelve fractions covering a wide range of weight‐average molecular weight (215 000 ≤ M̄ w ≤ 2 070 000) were used to characterise the polymer by light scattering, membrane osmometry and viscosity measurements. The Mark‐Houwink equations, established for 1 in two good solvents, 2,2,2‐trifluoroethanol (TFE) and 1,0 M aqueous NaCl solution, show that the polymer has a random coil configuration and that TFE is a thermodynamically better solvent than 1,0 M aqueous NaCl solution. The random coil configuration of 1 in TFE was confirmed from the dependence of the polymer dimensions on molecular weight.