Polymeric nanocapsules containing methylcyclohexane for improving thermally induced debonding of thin adhesive films

Abstract

The thin adhesive film with tunable interfacial adhesion can be applied in a broad range of display applications, from optically clear films to flexible devices. We have fabricated adhesive films including evaporable polymeric nanocapsules which can form thermally induced bubble gaps at the interface. These nanocapsules consisted of a poly(methyl methacrylate) core and a polyethyleneimine shell, and were impregnated with methylcyclohexane as a vaporization material. The evaporated core materials facilitated the desorption of thin adhesive film through bubble formation on the adhesive interface after thermal treatment, resulting in improved detachment of the adhesive layer. The optimization of the bubble gaps was performed to adjust the adhesive strength by varying the duration and temperature of thermal treatment, as well as the quenching temperature. The evaporable adhesive film with nanocapsule concentration of 1.0 wt % resulted in high transmittance of 94.9%, with the best adhesive strength reduction of 57.6% obtained after thermal treatment. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46586.

Debondable adhesives and their use in recycling

“…Another approach for thermal debonding with additives, is the incorporation of expandable microparticles into commercial adhesive formulations. 7,[124][125][126][127][128][129][130][131][132] A wide range of chemical or physical foaming agents can be incorporated into polymeric shells, such that elevated temperatures triggers considerable expansion of the microcapsule. This generates internal stress with propagation of cracks through the adhesive, leading to a loss of modulus and consequently, cohesive failure, (Scheme 10).…”

“…In an alternative method, organic additives are utilised which evaporate or decompose on application of thermal stimulus, as shown in Scheme 11. 124,125,[133][134][135][136] The gas produced migrates to the interfaces, causing volume expansion of the polymer matrix, and in some cases foaming.…”

Review on Adhesives and Surface Treatments for Structural Applications: Recent Developments on Sustainability and Implementation for Metal and Composite Substrates

“…When heated up, the substances evaporate and release gas into the interface of the bonded parts. The resulting gas bubbles weaken the bond, causing a more straightforward disassembly process (see Figure 11 ) [ 196 ]. After heat treatment, the adhesive bond still possesses about 50% of its initial strength.…”

“…( a ) Synthesis concept of a polymeric nanocapsule containing internal vaporizing material, namely nanocapsules composed by hydrophobic methylcyclohexane (MCH)/poly(methyl methacrylate (PMMA) in the core and polyethyleneimine (PEI) in the shell. ( b ) Schematic representation of debonding mechanism through the formation of bubble gaps at the interface of a thin film adhesive, by heating the adhesive system [ 196 ]. Reprinted from Journal of Applied Polymer Science, Vol.…”

Tensile Strength of Adhesively Bonded and Hybrid (Bonded/Riveted) Dissimilar Single-Lap Joints

“…One of the most frequently utilized joining techniques in advanced structures (like aerospace and automotive) is structural adhesive bonding [1][2][3][4][5]. However, the strength of the adhesive joint can be affected by many parameters such as environmental conditions [6][7][8]. One of the best ways to overcome such problems is to combine adhesive bonding with other joining techniques, thus, another type of joining technique (e.g., riveted joints) can compensate for the disadvantage of adhesive joining such as lack of strength.…”