Design of a High-Performance Dismantlable Adhesion System Using Pressure-Sensitive Adhesive Copolymers of 2-Hydroxyethyl Acrylate Protected with tert-Butoxycarbonyl Group in the Presence of Cross-Linker and Lewis Acid

Abstract

A dismantlable adhesion system satisfies both a strong bonding strength during use and a quick debonding process on demand in response to an external stimulus as a trigger for dismantling. In this study, we synthesized acrylate copolymers consisting of 2-( tert -butoxycarbonyloxy)ethyl acrylate (BHEA), 2-ethylhexyl acrylate (2EHA), and 2-hydroxyethyl acrylate (HEA) as the repeating units and evaluated the properties as dismantlable adhesives. First, the thermal degradation behavior of the obtained polymers was investigated by thermogravimetric analysis and IR spectroscopy. The BHEA-containing polymers were thermally stable during heating at a temperature below 150 °C, but they rapidly degraded, i.e., the deprotection of the tert -butoxycarbonyl groups occurred during heating at 200 °C. The onset temperatures for the deprotection depended on the BHEA and HEA contents and their sequence structures because the hydroxy group in the side chain accelerated the deprotection via an autocatalytic reaction mechanism. Shear holding power and 180° peel tests were carried out with the pressure-sensitive adhesive tapes using the BHEA-containing copolymers as the adhesive materials. The copolymers consisting of the BHEA, 2EHA, and HEA units with 25.7, 35.0, and 39.3 mol %, respectively, exhibited the highest adhesion strength and the subsequent quick reduction of the adhesion strength by heating during the dismantling process. The addition of hexamethylene diisocyanate as the cross-linker and Zn(acac) 2 as the Lewis acid to the adhesive polymers was demonstrated to be valid for the design of high-performance dismantlable adhesion systems. A change in the rheological properties during the dismantling process was important for a quick response and selective interfacial failure between the substrate and the adhesive.

Control of thermal, mechanical, and optical properties of three‐component maleimide copolymers by steric bulkiness and hydrogen bonding

“…Recently, the acceleration of the propagation rate of vinyl monomers containing a hydroxy group was reported for several polymerization systems, in which intermolecular and intramolecular hydrogen bonding is important to extraordinary enhancement of monomer reactivity. [49][50][51] Being different from the results reported in the literature, no outstanding incorporation of HEA and BHA was confirmed in this study because of fast cross-propagations between EHMI and RS. When the copolymerization was carried out using various comonomer ratios in the feed, that is, [RS]/[EHMI]/[HBA] = 1/1/1, 1/1/2, and 1/0.5/2 in molar ratio for the preparation of the copolymers 4b, 4b 0 , and 4b 00 , respectively, the copolymer composition slightly varied (see Table 1).…”

“…The apparent copolymerization rate and the molecular weight of the copolymers showed similar tendency, but more detailed discussion for the relative reactivity in this system was difficult because we have no data under unified copolymerization conditions. Recently, the acceleration of the propagation rate of vinyl monomers containing a hydroxy group was reported for several polymerization systems, in which intermolecular and intramolecular hydrogen bonding is important to extraordinary enhancement of monomer reactivity . Being different from the results reported in the literature, no outstanding incorporation of HEA and BHA was confirmed in this study because of fast cross‐propagations between EHMI and RS.…”

Debondable adhesives and their use in recycling

“…At 200 °C, the protecting group decomposes, releasing isobutene and carbon dioxide, and causing a loss of polymer molecular weight and interfacial failure of the adhesive. 101 Another similar approach involves the deblocking and degradation of blocked isocyanate crosslinkers (Scheme 8b). 102,103 These polymers contain weak bonds from the reaction of an isocyanate with a hydrogen active compound such as an acetate, amine or alcohol.…”

“…Scheme 8 Mechanism of thermally induced "debonding-on-demand" by the use of (a) thermal degradation of a tert-butoxy-carbonyl, 101 (b) deblocking and degradation of blocked isocyanate crosslinkers. 102,103 Furthermore, there are several hydrogen bonding motifs which allow thermal debonding, in addition to the UV debondable UPy discussed earlier.…”

An Efficiently Reworkable Thermosetting Adhesive Based on Photoreversible [4+4] Cycloaddition Reaction of Epoxy‐Based Prepolymer with Four Anthracene End Groups

“…Adhesives, which act on the surface of the two substrates and adhere firmly them together, [ 1 ] are playing an important role in industrial production and many aspects of daily life. [ 2 ] A variety of thermoplastic and thermosetting polymers can be used to prepare adhesives, such as, acrylic esters, [ 1–11 ] epoxy resins, [ 12–15 ] polyurethanes, [ 16,17 ] thiol‐ene networks, [ 18,19 ] azo‐benzene derivatives, [ 20,21 ] etc. Usually, thermosetting adhesives provide excellent bonding strength and stability, due to their permanently cross‐linked polymer networks.…”