Investigation of electrostatic interactions in laponite-polyacrylic acid nanocomposites

Nanocomposites provides a unique opportunity to enhance thermal, mechanical, and waterproof resistance properties of polymer. The effectiveness of these enhancements typically depends on the optimal dispersion and interaction of nanofillers within the polymer matrix. The primary objective of this study is to provide direct chemical evidence for electrostatic interactions between Laponite nanofiller and polyacrylic acid. Samples were prepared by mixing Laponite dispersion and aqueous polyacrylic acid (PAA) that were adjusted to various pH conditions. We observed, an IR peak shift in the carbonyl peak of PAA and Si–O peak of Laponite to lower wave number in nanocomposite, with the maximum shift at pH 7. UV–Vis results also showed a hypsochromic shift in the carbonyl peak of PAA due to the interaction with Laponite. The extent of peak shift in IR, and UV–Vis region for the PAA-Laponite dispersion was found to be influenced by the molar mass of PAA used in the formulation of Laponite-PAA nanocomposite and pH of the medium. These results along with zeta potential measurements strongly suggest that electrostatic forces are in play between deprotonated PAA and the positively charged rim of Laponite in promoting electrostatic interactions between Laponite and PAA. The findings of the study can have a strong bearing on the design of next generation high performance coatings, sealants, and adhesives.