Aqueous self-assembly of wheat starch paste into low-responsive microgels for stabilizing mounted paper-based...

Wheat starch paste has been historically employed as the core adhesive for the mounting of Chinese paper-based artworks. However, it is inherently prone to aging-induced deformation, mainly due to the recrystallization of amylose. Herein, an aqueous self-assembly strategy was proposed to transform wheat starch paste into microgels, aiming to induce amylose recrystallization prior to application while preserving its adhesion. During periodic water exchange, the paste underwent a time-dependent structural evolution. Amylose first recrystallized via hydrogen bonding, followed by encapsulation of recrystallized amylose by amylopectin to form microgels, and subsequent densification with prolonged soaking. Consequently, the paste's viscosity, temperature responsiveness, and bonding strength gradually decreased, mainly due to reduced free hydroxyl groups from hydrogen bonding. Meanwhile, the paste was purified, and its pH rose as residual proteins and acidic impurities were removed. After evaluation, with longer soaking time of paste, the mounted paper showed weakened moisture responsiveness, decreased flexibility and chromatic aberration (ΔE), and stable pH after natural drying and accelerated aging, indicating improved dimensional stability and aging resistance. However, it is worth noting that excessively long soaking time may also increase the risk of insufficient bonding and brittle fracture in the mounted works, especially for scroll calligraphy and paintings.