title: Tailoring the near-surface composition profiles of pressure-sensitive adhesive films and the resulting mechanical properties.
abstract: We present a possibility of tailoring the near-surface composition profiles of pressure sensitive adhesive (PSA) films by an exposure to atmospheres of different relative humidities (RHs). The statistical copolymer P(EHA-stat-20MMA) with a majority of ethylhexylacrylate (EHA) and a minority of methylmethacrylate (MMA), being cast from a toluene based solution, is chosen as a model system. The near-surface composition profile is probed with X-ray reflectivity. All probed samples show an enrichment of PMMA at the sample surface; however, the near-surface PMMA content strongly increases with increasing RH. The influence of the RH on the composition profile is present down to a depth of 50 nm. Therefore the surface tensions being derived from contact angle measurements do not show any measurable humidity dependence. In contrast, in a mechanical tack test with a smooth punch surface, a strong influence is probed. This observation can be explained by considering the integrated PMMA content over an appropriate near-surface region and the resulting impact on the cavitation process.
authors: Technische Universität München, Physik-Department E13, Lehrstuhl für Funktionelle Materialien, James-Franck-Strasse 1, 85747 Garching, Germany.
authors: Alexander
authors: A
authors: Diethert
authors: Katharina
authors: K
authors: Ecker
authors: Yana
authors: Y
authors: Peykova
authors: Norbert
authors: N
authors: Willenbacher
authors: Peter
authors: P
authors: Müller-Buschbaum