Gelation of hydroxyethyl cellulose aqueous solution induced by addition of colloidal silica nanoparticles

In this study, a series of hydrogels based on the physical adsorption between hydroxyethyl cellulose (HEC) and colloidal silica nanoparticles (SNPs) were developed, and the effects of SNPs addition on the prepared gels were also investigated. The addition of SNPs into the HEC solution (1.0 wt%) induced gelation, and the gel strength was enhanced by increasing the SNPs concentration from 5 to 20 wt%, which was due to the formation of a denser gel network, as evidenced by SEM observations. Rheological tests suggested that the gelation temperature (T_g) was decreased with the increasing SNPs addition, and the gels exhibited slightly thermal hysteresis, with a temperature lag of 6-7 °C. However, when the SNPs concentration was above 21 wt%, a phase separation was observed. Furthermore, it was found that the addition of SNPs led to the intensified hydrogen bonds between the HEC molecules and the added SNPs, which may be the predominant factor governing the adsorption process. Overall, a facile method for hydrogel preparation was proposed in this study, and the gel properties were also systematically investigated. These results may provide useful information to the field of material science.