A simple strategy to modulate the adhesive properties of water-based acrylic pressure-sensitive adhesives: Interaction of carboxylic acids in polymeric surfactants with monovalent metals ions

Abstract

Amidst growing environmental concerns over solvent-based adhesives, water-based acrylic pressure-sensitive adhesives (PSAs) offer a sustainable alternative, yet optimizing their performance remains challenging. This study systematically investigated the role of pH regulation and monovalent metal ions in optimizing the adhesion properties of water-based acrylic PSAs employing polymeric surfactants. In contrast to the conventional approach, we added various alkaline solutions (NaOH, KOH, and NH₄OH) to the pH-dependent polymeric surfactant-dominated emulsion polymerization process to explore their multiple effects on the microstructure and mechanical properties of the adhesives. Through comprehensive small-angle X-ray scattering (SAXS) and rheological evaluations, it was demonstrated that the type of alkaline solutions has a significant effect on the peel and shear strength of PSAs, with NH₄OH neutralization yielding excellent peel strength at lower pH and NaOH or KOH enhancing shear strength and thermal stability at higher pH. These findings highlight the important interactions between carboxylic acid functional groups and monovalent metal ions and provide a fundamental approach for the custom development of environmentally friendly adhesives with optimized performance attributes. This study provides a simple strategy for modulating the adhesive properties of waterborne acrylic PSAs, providing a basis for realizing sustainable industrial adhesive applications. © 2024 Elsevier Ltd