TY - JOUR

T1 - Design of Reversible Adhesives by Using a Triple Function of Ionic Liquids

AU - Wanghofer, Florian

AU - Kriehuber, Matthias

AU - Reisinger, David

AU - Floh, Florian

AU - Wolfahrt, Markus

AU - Schlögl, Sandra

N1 - Publisher Copyright: © 2024 The Authors. Macromolecular Materials and Engineering published by Wiley-VCH GmbH.

PY - 2024/5/2

Y1 - 2024/5/2

N2 - Reversible adhesives are crucial for a circular economy of composites as they play a key role for rework, repair, and recycling of adhesively bonded components. Herein, electrically debondable adhesives are prepared by introducing ionic liquids in dynamic thiol–epoxy networks. The function of the ionic liquid in the networks is threefold as it accelerates the curing reaction between thiol and epoxy monomers, facilitates electrical debonding, and catalyzes thermoactivated transesterification reactions, required for rebonding at elevated temperature. A library of 1,3-dibutylimidazolium-based ionic liquids with varying anions is synthetized and it is found that 1,3-dibutyl-1H-imidazol-3-ium dicyanamide (DiButIm─N(CN)2) is superior in accelerating bond-exchange reactions between hydroxy and ester moieties at elevated temperature. Thus, a thiol–epoxy resin containing 20 wt% of DiButIm─N(CN)2 is used to impregnate glass fiber mats yielding adhesive connections for aluminum substrates with 10.2 MPa pull-off strength. The adhesive connections are successfully debonded at the metal–adhesive interface by applying 120 V. The samples are then rebonded via the thermoactivated change in the networks’ viscoelastic properties and ≈80% (8.1 MPa) of their original bond strength can be regained. By providing a simple strategy to synthetize reversible adhesives, this approach paves a way toward improved recyclability and repairability of adhesively bonded structures.

AB - Reversible adhesives are crucial for a circular economy of composites as they play a key role for rework, repair, and recycling of adhesively bonded components. Herein, electrically debondable adhesives are prepared by introducing ionic liquids in dynamic thiol–epoxy networks. The function of the ionic liquid in the networks is threefold as it accelerates the curing reaction between thiol and epoxy monomers, facilitates electrical debonding, and catalyzes thermoactivated transesterification reactions, required for rebonding at elevated temperature. A library of 1,3-dibutylimidazolium-based ionic liquids with varying anions is synthetized and it is found that 1,3-dibutyl-1H-imidazol-3-ium dicyanamide (DiButIm─N(CN)2) is superior in accelerating bond-exchange reactions between hydroxy and ester moieties at elevated temperature. Thus, a thiol–epoxy resin containing 20 wt% of DiButIm─N(CN)2 is used to impregnate glass fiber mats yielding adhesive connections for aluminum substrates with 10.2 MPa pull-off strength. The adhesive connections are successfully debonded at the metal–adhesive interface by applying 120 V. The samples are then rebonded via the thermoactivated change in the networks’ viscoelastic properties and ≈80% (8.1 MPa) of their original bond strength can be regained. By providing a simple strategy to synthetize reversible adhesives, this approach paves a way toward improved recyclability and repairability of adhesively bonded structures.

KW - dynamic polymer networks

KW - electrical debonding

KW - ionic liquids

KW - reversible adhesives

KW - vitrimers

UR - http://www.scopus.com/inward/record.url?scp=85191783321&partnerID=8YFLogxK

UR - https://pureadmin.unileoben.ac.at/portal/en/publications/design-of-reversible-adhesives-by-using-a-triple-function-of-ionic-liquids(a83ca346-617b-4d65-8ad0-bffb63220f62).html

U2 - 10.1002/mame.202400011

DO - 10.1002/mame.202400011

M3 - Article

AN - SCOPUS:85191783321

VL - 309.2024

JO - Macromolecular materials and engineering

JF - Macromolecular materials and engineering

SN - 1438-7492

IS - 9

M1 - 2400011

ER -