Chemical factors affecting the wetting time of poly(acrylic acid) xerogel powder synthesized by precipitation polymerization technique

The cross-linked poly(acrylic acid) as a hydrophilic polymer network can imbibe several times its weight through the swelling process, which leads to the media’s viscosity enhancement as a thickener. Once this hydrogel originates from the xerogel structure obtained from the precipitation polymerization technique, it is preferred to be easy-to-disperse powder in the aqueous media, otherwise, the coagulation of powder formed in the swelling media requires long and vigorous stirring for dispersion. Therefore, chemical factors in the synthetic step affecting the wetting time of the powder are crucial variables that must be traced for the xerogel quality improvement. In this paper, various concentrations of hydrophobic/hydrophilic comonomers such as stearyl methacrylate, lauryl methacrylate, and acrylamide, as well as a variety of nonionic/anionic surfactants have been investigated to reduce the wetting time and improve the thickening properties of poly(acrylic acid)-based xerogel synthesized by precipitation polymerization technique. Among the co(ter)polymers prepared, the terpolymer of acrylic acid, lauryl methacrylate, and acrylamide, having the optimum viscosity, showed a wetting time of 9 min.