Composite polyurethane adhesives that debond-on-demand by hysteresis heating in an oscillating magnetic field

Abstract

Debond-on-demand adhesives are an emerging industrially important technology, allowing components and materials to be readily separated when required, facilitating recycling. Herein, a composite adhesive has been synthesized that can undergo hysteresis heating to debond-on-demand through direct exposure to an oscillating magnetic field. The adhesive is composed of a polyurethane continuous phase with commercial, unfunctionalized iron oxide particles as the filler (between 1 and 20 wt%). 2 mg of the composite containing 8 wt% iron oxide particles was able to bond various surfaces including glass, wood, aluminium and polyvinyl chloride and support a static load of 100 grams. The composites were fabricated by melt processing which resulted in a relatively inhomogeneous dispersion of particles. The values of the Young's modulus, the ultimate tensile strength, modulus of toughness of the adhesives were comparable to those exhibited by a commercial hot melt adhesive but relatively invariant over the series of composites examined. When subjected to hysteresis heating from an oscillating magnetic field, the rate of temperature increase was dependent on the loading level of Fe3O4. Debonding times decreased from approximately 5 minutes to less than 30 seconds exposure to the oscillating magnetic field as the Fe3O4 loading level increased from 1 to 20%. These results will help guide the design of new debond-on-demand polymers that can be addressed through exposure to an oscillating magnetic field.

Stimuli-responsive temporary adhesives: enabling debonding on demand through strategic molecular design

“…Stimuli that require direct access to the adhesive material to provoke debonding, such as UV light or chemical triggers, are not suitable for applications that bond impermeable or opaque substrates. 228 To overcome this obstacle, adhesives may be responsive to magnetic elds with ferromagnetic or conductive additives, such as iron-based powders, aluminum, Copyright 2020 American Chemical Society. 31,32,162 cobalt, or nickel.…”

“…38 Applying a magnetic eld elicits molecular motions, rotations, or vibrations, that transfers thermal energy to the adhesives, which can lead to debonding with the previously discussed mechanisms. 38,228,229 In one example from Greenland and coworkers, a composite adhesive with Fe 3 O 4 particles (8 wt%) bonded wood, aluminum, glass, and polyvinyl chloride (PVC) substrates with a tensile strength of 1.35 MPa. 228 Authors hypothesized that an oscillating magnetic eld (OMF) would heat the material due to hysteresis loss, which would lead to debonding by dismantling the intermolecular interaction network.…”

“…38,228,229 In one example from Greenland and coworkers, a composite adhesive with Fe 3 O 4 particles (8 wt%) bonded wood, aluminum, glass, and polyvinyl chloride (PVC) substrates with a tensile strength of 1.35 MPa. 228 Authors hypothesized that an oscillating magnetic eld (OMF) would heat the material due to hysteresis loss, which would lead to debonding by dismantling the intermolecular interaction network. An OMF was applied to this adhesive, leading to complete debonding from 30 seconds to ve minutes, depending on the wt% loading of the Fe 3 O 4 particles.…”

Trivalent Cations Detection of Magnetic-Sensitive Microcapsules by Controlled-Release Fluorescence Off-On Sensor

“…Superparamagnetic nanoparticles can effectively avoid aggregation and are evenly distributed because there is no magnetic hysteresis between them [ 37 ]; meanwhile, the thermomagnetic effect provides heating compared with the non-magnetic materials [ 38 ]. In previous studies, a high-frequency magnetic field (HFMF) was developed as a trigger to release the functional core materials from magnetic-based microcapsules [ 39 , 40 , 41 , 42 ]. To date, only a few attempts have been reported on the release mechanism when using heat to realize drug release by employing HFMF, which affects the thermodynamics of the microcapsule molecular chains.…”

Wide Area Reversible Adhesive for In‐Space Assembly

“…Many different heating methods could be used for ATSP's bonding. The induction heating is an attractive method as it can heat the parts rapidly, and specifically, it enables localized heating of inductively susceptible materials as previously demonstrated in thermoplastics loaded with inductively-susceptible fillers [18,19] ; thus, it can save energy usage in space.…”