Combined Dynamic Network and Filler Interface Approach for Improved Adhesion and Toughness in Pressure-Sensitive Adhesives

Of importance for adhesive materials, particularly pressure-sensitive adhesive (PSA) systems, is the ability to increase bulk toughness without reduction of adhesion. Previous approaches for increasing PSA durability sacrifice permanent cross-linking or adhesive potential, limiting performance. In this work, covalent adaptable networks (CANs) derived from thiol-thioester exchange (TTE) are utilized as a basis for adhesive films. Tensile and single-lap shear tests were conducted for adhesive materials containing no filler, 15 wt % nanoparticles functionalized with thioester-containing acrylate, or 15 wt % nanoparticles functionalized with nonthioester-containing acrylate. Additionally, fatigue experiments were conducted on unfilled adhesives. Results indicate that TTE improves toughness, adhesion, and fatigue in unfilled materials. Filled adhesives with activated TTE showed a nearly fourfold increase in adhesion with slightly reduced toughness compared to uncatalyzed filled specimens. This work has implications in many industries, from biomedical to automotive, as toughness and fatigue resistance are important considerations for adhesive applications.