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

Abstract

The solid–liquid phase transition is always the key to the design and preparation of reworkable adhesives. However, an efficient photoinduced reworkable thermosetting adhesive at room temperature remains a challenge. Here, a photoinduced reworkable thermosetting adhesive of epoxy‐based prepolymer with four anthracene end groups are prepared. The highly active light‐induced [4+4] cycloaddition and depolymerization, as well as a large number anthracene groups endow this adhesive with high optical activity. Soft segments of polyether amines are used to adjust glass transition temperature of these cross‐linked networks which is significant for highly efficient solid–liquid phase transition of photoinduced reworkable adhesive at room temperature. As a reworkable adhesive, the obtained AER/D2000 exhibits desirable viscosity, lap shear strength up to 2.4 MPa for quartz glass substrate in the cross‐linked state, and ideal reworkable efficiency as high as 91.7%. Therefore, this research provides a strategy for a photoinduced reworkable adhesive, and as an alternative for heat‐induced reworkable adhesives.

Recoverable solvent-free small molecular supramolecular pseudoeutectic adhesives with a wide temperature range

“…Adhesives are widely used in all walks of life, such as electronics, [1][2][3][4][5] aerospace, [6][7][8][9][10] automotive industry, 11,12 medical industry [13][14][15][16][17][18][19] etc. From conventional resins [20][21][22][23] to new catechol-based adhesives, [24][25][26][27][28][29] polymeric structures are essential to achieve strong adhesion due to intra-chain covalent bonds and inter-chain entanglements. Nonetheless, it is usually arduous and time-consuming to remove polymeric adhesives that remain on the substrates after bonding.…”

Photo‐Controlled [4+4] Cycloaddition of Anthryl‐Polymer Systems: A Versatile Approach to Fabricate Functional Materials

“…The cross-linked anthracene-containing epoxy-based polymer network exhibits photo-reversible adhesive property with adhesion strength of 2.4 MPa and reworkable efficiency of 91.7%. [49] The cross-linking of the anthryl groups was carried out by irradiation at 365 nm (21.25 mW/cm 2 ) for 20 min and the decross-linking at 254 nm (0.8 mW/cm 2 ). Moreover, the crosslinked polyurethane network synthesized from polycaprolactone diol and 4,4'-methylenebis (cyclohexyl isocyanate) and fused with 1,4-butanediol and anthracene-containing diol showed enhanced bonding strength of up to 7.5 MPa (Figure 9, structure 6).…”

Debonding-on-demand adhesives based on photo-reversible cycloaddition reactions

“…In contrast, photoinduced processes that enable ''direct'' remote manipulation of the macroscopic properties of materials by irradiating light of specific wavelengths and intensities are useful for DoD adhesives under ambient conditions. 1 Typically, photo-reversible covalent bonding reactions include [2+2]-and [4+4]-type photochemical cycloadditions of thymine, 24 coumarin, [25][26][27] and anthracene, [28][29][30][31][32][33] trans-cis photoisomerization of azobenzene, 34 and photolysis of trithiocarbonates. [35][36][37][38] Dynamic covalent polymer networks incorporating these lightinduced reversible reactions have a wide range of applications, including self-healing polymers [39][40][41][46][47][48][49][50] and shape memory materials.…”

“…Typically, photo-reversible covalent bonding reactions include [2+2]- and [4+4]-type photochemical cycloadditions of thymine, 24 coumarin, 25–27 and anthracene, 28–33 trans – cis photoisomerization of azobenzene, 34 and photolysis of trithiocarbonates. 35–38 Dynamic covalent polymer networks incorporating these light-induced reversible reactions have a wide range of applications, including self-healing polymers 39–41,46–50 and shape memory materials.…”