Enhanced Adhesive and Thermal Properties of Waterborne Acrylic Pressure-Sensitive Adhesives via Graphene Oxide/Polymeric Surfactant Synergy: Sequential Adsorption-Grafting-Encapsulation Mechanism

Abstract

A high solids (about 30 wt %) water-borne acrylic pressure-sensitive adhesive (PSA) was prepared by emulsion polymerization using graphene oxide (GO) as a particulate surfactant and a random poly(n-butyl acrylate-stat-acrylic acid) copolymer, P(n-BA-stat-AA), as an auxiliary polymeric surfactant, thereby avoiding the colloidal instability commonly observed with conventional low-molecular-weight surfactants. FT-IR, Raman, and XPS analyses confirmed a sequential "adsorption-grafting-encapsulation" mechanism. P(n-BA-stat-AA) first adsorbs onto GO via hydrogen bonding and electrostatic attraction, then may partially grafts through radical reactions, and is finally encapsulated by the growing polymer shell. This process partially restored the pi-pi stacking and incorporated GO as cross-linking nodes. The resulting latex has a narrow modal particle diameter of about 200 nm and remains stable for several months. Incorporating 4 wt % GO increased the 180 degrees peel strength to 19.11 N/25 mm, extended the shear holding time from 3 to 1388 min, and raised the shear-adhesion-failure temperature from 50.8 to 115.6 degrees C, demonstrating simultaneous improvements in adhesion, cohesion, and heat resistance. Thermogravimetric analysis revealed delayed backbone degradation and reduced mass-loss rates, confirming the thermal-shielding and diffusion-barrier effects of the layered filler. Overall, these findings establish a clear structure-property relationship: electrostatic repulsion from GO and steric hindrance from P(n-BA-stat-AA) together generate a nanoconfined hybrid network, imparting exceptional mechanical durability and thermal stability. This approach offers a promising pathway to high-performance water-based PSAs.