Highly stretchable and transparent hybrid double-network acrylic nanocomposite adhesive based on the synergy between stretchable silica nanoparticles and multifunctional dual crosslinkers

Abstract

Transparent polymer adhesives that are highly stretchable and optically clear are increasingly required owing to the development of stretchable electronic materials. Conventional acrylic polymer adhesives have low elastic moduli and exhibit poor recoveries following deformation that lead to permanent out-of-plane wrinkle defects. Consequently, acrylic adhesives that are elastic and flexible are sought after to improve stretchability and recoverability; however, the functional trade-off that exists between adhesion and elasticity must first be surmounted. In this study, we developed a hybrid double-network acrylic nanocomposite adhesive that is highly stretchable and optically transparent owing to the synergy between highly stretchable silica nanoparticles and multifunctional dual crosslinkers. Specifically, stretchable silica nanoparticles that behave stretchily and are prepared by attaching photoreactive flexible chains to the surfaces of rigid inorganic silica nanoparticles are added to an acrylic resin along with pentaerythritol triacrylate and poly(propylene glycol) diacrylate, as multifunctional dual crosslinkers, to form an elastic double-network structure through UV curing. The dual-crosslinked acrylic nanocomposite adhesive is highly elastic and flexible, and exhibits a high recovery rate of 83.8 %, a fast stress-relaxation ratio of 10.2 %, and an elongation of 461 %. Furthermore, the new acrylic nanocomposite adhesive exhibited a relative optical transmittance of 92.9 % and an adhesion strength of 18.4 N/25 mm, despite its high (5 wt%) nanoparticle concentration, highlighting its potential as a stretchable optoelectronic adhesive.