Homogenous modification of cellulose with acrylamide in NaOH/urea aqueous solutions

A series of cellulose polyelectrolytes, containing acylamino and carboxyl groups, were homogenously synthesized from cellulose with acrylamide in NaOH/urea aqueous solutions. The structure and solution properties of the polyelectrolytes were characterized with elemental analysis, FTIR, NMR, viscometer and zeta-potential measurement. The nitrogen content and total degree of substituent (DS) of the derivatives increased with increasing of the molar ratio of acrylamide to the anhydroglucose unit (AGU) and the cellulose concentration. The DS of carboxyl groups hardly changed because of the similar reaction and hydrolysis conditions, while the DS of acylamino groups increased with increasing of the total DS values of the products. The polyelectrolytes are soluble in water at a total DS as low as 0.36, and the zeta-potential values in pure water are in the range of −15 to −25 mV. The [η] values of the polyelectrolytes in NaCl aqueous solutions increased apparently with an increase of the pH value in the lower pH region, and reached the maximum value at the pH range from 5 to 6, and while hardly changed at the pH range from 7 to 12. This work provided a facile method for the synthesis of cellulose polyelectrolytes with two different functional groups.