Pressure-Sensitive Adhesion System Using Acrylate Block Copolymers in Response to Photoirradiation and Postbaking as the Dual External Stimuli for On-Demand Dismantling

We have demonstrated the validity of a new type of pressure-sensitive adhesion system using block copolymers containing a poly(2-ethylhexyl acrylate) (P2EHA) segment as the low glass transition temperature polymer and a poly(tert-butyl acrylate) (PtBA) or poly(isobornyl acrylate) (PIBoA) segment as the reacting polymer in the presence of a photoacid generator (PAG). This adhesion system can be easily debonded because of a change in the polymer properties of the adhesives by acid-catalyzed deprotection uniquely occurring during the photoirradiation followed by postbaking. We investigated the transformation of PtBA and PIBoA into poly(acrylic acid) using IR spectroscopy and a thermogravimetric analysis in the presence of p-toluenesulfonic acid and the PAGs. The block copolymers with a well-defined molecular structure were then synthesized by atom transfer radical polymerization, and their adhesive properties were evaluated using the 180° peel test. The block copolymers showed superior adhesion property than a random copolymer and polymer blends, due to the microphase separation of the block copolymers. A drastic change in the adhesive strength of the block copolymers was observed in response to the dual external stimuli consisting of UV irradiation and the subsequent heating.