A novel nanocomposite hydrogel system for synergistic paper deacidification and reinforcement

Abstract

Acidification is one of the major factors exacerbating paper deterioration, rendering documents brittle and prone to crumbling—even under gentle handling. This process is widespread among paper-based artifacts and progresses rapidly, posing a serious threat to their long-term preservation. As such, the need for effective deacidification and reinforcement methods in the conservation and restoration of paper artifacts is becoming increasingly urgent. This study proposes an innovative dual-purpose nanocomposite system, GG-C-M, achieving both deacidification and reinforcement effects on paper artifacts. The system is composed of a hydrogel matrix loaded with deacidifying and structural reinforcement agents. We analyzed the physicochemical properties—including microscopic morphology, pH, alkali reserves, and tensile strength—of acidified, dry heat-aged, and UV-aged paper samples before and after treatment with GG-C-M. Our results show that GG-C-M effectively treats severely acidified paper (pH ≤ 5.0), restoring it to a mildly alkaline state as well as improving their mechanical properties. The treatment significantly improves those physiochemical properties, while also mitigating adverse macroscopic and microscopic side-effects such as edge curling, increased thickness, whitening, and particle residue—issues commonly observed after direct application of sodium carboxymethyl cellulose nano-Mg(OH)₂ (C-M) dispersion. The proposed nanocomposite system offers advantages such as biocompatibility, localized treatment, controllable swelling, strong adsorption, and easiness of application.