Enhancing Pressure Sensitive Adhesive Performance Using Acetylated Carboxylated Cellulose Nanocrystals

Carboxylated cellulose nanocrystals (cCNCs) were acetylated to varying degrees of substitution to enhance their compatibility with the hydrophobic acrylic polymer matrix in pressure-sensitive adhesives (PSAs). The contact angle measurements showed the transition of the cCNCs from hydrophilic to hydrophobic properties. The least hydrophilic acetylated cCNCs, with a degree of substitution of 0.42, significantly enhanced PSA performance, improving tack, peel strength, and shear adhesion, compared to the base formulation and that with unmodified cCNCs. The findings emphasize the crucial role of nanoparticle dispersion, where lower interfacial tension leads to improved dispersion and enhanced latex particle coalescence during film drying, consequently yielding superior mechanical, thermal, and barrier properties of the nanocomposite PSAs. Overall, the ability to fine-tune the degree of substitution of the acetylated cCNCs points to their broader potential applications in coatings, hydrogels, and other advanced materials, allowing for adjustments in hydrophilicity to match specific application needs.