Direct rheological measurement of serial photopolymerization and photodegradation processes of pressure-sensitive adhesives composed of O-acyloxime-based photolabile crosslinkers and butyl acrylate

The debonding of pressure sensitive adhesives (PSAs) induced by external stimuli attracts much attention. Recently, novel O-acyloxime based photolabile crosslinkers have been proposed and applied to PSAs that are degradable photochemically. Herein we report the results of in-situ rheological measurements for formulations composed of butyl acrylate (BA) and O-acyloxime-based photolabile crosslinkers under irradiation at 365 nm by using a photorheometer. Formulations consisted of BA, a crosslinker, and 2-isopropylthioxanthene-9-one showed the increase in storage and loss moduli, and absolute value of complex viscosity on irradiation in the absence and presence of a photoinitiator. In addition, we could observe peaks in the curves of parameter changes for a formulation containing ethyl acetate, showing serial photopolymerization and photodegradation processes in a single measurement. (C) 2016 Elsevier B.V. All rights reserved.