Near-Interface Composition in Pressure Sensitive Adhesives at the Adhesive-Adherent Interface

Abstract

The adhesive-adherent interface of a model system for pressure sensitive adhesives (PSAs) is probed with neutron reflectivity to reveal its inner composition. The statistical copolymer poly(ethylhexyl-stat-d-methylmethacrylate) P(EHA-stat-dMMA), consisting of 80wt% ethylhexylacrylate (EHA) and 20wt% deuterated methylmethacrylate (dMMA), is used as model PSA. Its interface with silicon is investigated. The surface cleaning treatments applied to silicon strongly affect the inner near interface structure of the solution cast P(EHA-stat-dMMA). Two opposite behaviors are observed. On acid cleaned silicon the soft and sticky majority component EHA enriches at the interface to the substrate. In contrast, the glassy minority component dMMA forms an enrichment layer at the interface to the basic cleaned silicon surface. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.