While the chemical reaction between poly(vinyl alcohol) and sodium tetraborate decahydrate to synthesize the hydrogel commonly referred to as Slime is both a popular undergraduate experiment and chemical demonstration, there is no general agreement in the chemical literature as to whether the increase in viscosity of this material is due to covalent or hydrogen bonding. As a result, the underlying chemistry remains unexplained. Previous work involving the reaction of this hydrogel with strong acids is consistent with covalently bonded crosslinks. Subsequent viscosity studies have led others to conclude that covalent bonding was not responsible for the formation of this hydrogel. Consequently, laboratory manuals and the chemical education literature continue to split over the proposed molecular structure of Slime. To reconcile these experimental results, a series of gels at increasing pH and borate concentrations have been prepared that allows the formal gel point of this system to be identified. The network solid that forms under these conditions clearly shows that covalent bonding is responsible for the formation of this hydrogel. Furthermore, the network solid that forms at these higher pH's and concentrations of borate confirms that the formulation known as Slime exists as a covalently bonded pre-gel viscous fluid. 

Gelation chemistry of poly(vinyl alcohol) and sodium tetraborate decahydrate

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.