Contact-induced molecular rearrangement of acrylic acid-incorporated pressure sensitive adhesives

Abstract

Although recent literatures have pointed out that viscoelastic dissipation is the main mechanism affecting the adhesion of pressure sensitive adhesives (PSAs), the controversial issue found previously has spurred us to be interested in the contribution of surface chemistry and physics. Herein, it was found that changes in the surface energy of PSAs caused a significant increase in the adhesion energy via rearrangement of the polymer chains, inducing reorientation of the polar group toward the metallic adherend. The adhesion energy increased with increasing contact time on the adherend, where the adhesion performance of acrylic acid-incorporated PSA increased by more than 300% after 24 h contact with stainless steel. The surface energy of the adhesives were calculated as a function of contact time via contact angle measurements and using the Fowkes theory in order to substantiate the changes in the surface properties influencing the adhesion. The surface chemistry of the PSAs was analyzed by Fourier-transform infrared analysis and time-of-flight secondary ion mass spectrometry, which suggest that the enhanced adhesion of acrylic acid-incorporated PSA is due to the contact time-dependent mechanism, in which induces the polymer chains rearranged and polar groups exposed at the interface.