Ultrafast Self-Healable Interfaces in Polyurethane Nanocomposites Designed Using Diels–Alder “Click” as an Efficient Microwave Absorber

Abstract

In the recent times, multifunctional materials have attracted immense interest. Self-healing polymers are in great demand in almost every coating application. With an increase in electromagnetic (EM) pollution, curbing the same has become an urgent necessity. Lightweight coatings and conducting polymeric materials are being highly researched upon in this regard, and combining these properties with self-healing systems would open new avenues in EM interference (EMI) shielding (specifically in the microwave frequency domain) applications. In the current study, a novel approach toward the development of microwave shielding materials capable of self-healing through microwave heating has been attempted. A covalently cross-linked material was developed using Diels–Alder (DA) chemistry, which shows self-healing properties when stimulated by heating. Herein, reduced graphene oxide grafted with magnetite nanoparticles (rGO/Fe 3 O 4 ) was covalently cross-linked to thermoplastic polyurethane using DA chemistry. The addition of multiwalled carbon nanotubes into these nanocomposites led to exceptional EM wave shielding and self-healing properties through a synergistic effect. The synergism led to exceptional EMI shielding of −36 dB, primarily through absorption in the microwave region of the EM spectrum. When used in the form of thin coatings of about 1 mm in thickness, the shielding value reached −28 dB, manifesting in more than 99% attenuation of EM waves through absorption. The material was also found to be capable of healing scratches or cuts through microwave irradiation.

Development of Self-Healable Organic/Inorganic Hybrid Materials Containing a Biobased Copolymer via Diels–Alder Chemistry and Their Application in Electromagnetic Interference Shielding

“…For example, conductivity is greatly required for electronic applications such as microelectronics packaging [33], medical devices [34], artificial skins [35], and electromagnetic interference (EMI) shielding [36]. So far, several research studies have been performed to develop DA based nanocomposites, wherein conductive fillers such as metallic nanoparticles [37], carbon nanotubes [38,39,40], and graphene [41,42,43] were incorporated into the material systems. In particular, graphene has attracted a great interest because this two-dimensional carbon allotrope possesses large aspect ratio as well as superior carrier mobility, and can thereby serve as a promising material in EMI shielding technology [43,44,45].…”

Fabrication of Self-Healable Magnetic Nanocomposites via Diels−Alder Click Chemistry

“…This signal change clearly indicated the formation of DA adducts via a DA reaction. For the PCLF-DA-5 sample, the peak at 756 cm −1 corresponding to furfuryl moiety also disappeared, which again confirmed the occurrence of DA reaction that change the original furan rings in pristine PCLF [30]. Schematic representation of the thermo-reversible DA network formed from furan/maleimide, MWCNT/furan, and MWCNT/maleimide combinations.…”

“…The incorporation of inorganic nanomaterials for the fabrication of hybrid materials would further offer multifunctional properties that create expanded opportunities for developing advanced applications. For example, self-healing nanohybrids based on DA reactions with the incorporation of MWCNTs (multiwalled carbon nanotubes), GOs (graphene oxide), or inorganic nanoparticles showed potential for practical use [26][27][28][29][30][31][32]. In particular, carbon nanotubes have received a great interest due to their superior electrical, thermal, and mechanical properties compared to those of traditional fiber materials [33,34].…”

Advances in intrinsic self-healing polyurethanes and related composites

“…A similar strategy was reported for Diels-Alder modied graphene-PU composites healable with infrared laser. 122 Ultrafast healing was obtained due to excellent thermal conduction of graphene opening a promising way for exible electronic devices repair. Lignin-modied graphene healable PU nanocomposites were prepared in a facile, aqueous-based and green method.…”