Abstract
Thermally self-healing graphene-nanoplate/polyurethane (GNP/PU) nanocomposites were prepared via a bulk in-situ Diels–Alder (DA) reaction. Graphene-nanoplate (GNP) was used as a reinforcement and crosslinking platform by a DA reaction with a furfuryl-based chain extender of polyurethane (PU). Results showed that a DA reaction occurred in GNP during the PU forming cure process. This procedure is simple and solvent free because of the absence of any independent surface modification process. Through the calculation of the interfacial tensions, the conditions of the bulk in-situ DA reaction were determined to ensure that GNP and the furfuryl group can react with each other at the interface during the curing process without a solvent. The prepared composites were characterized in terms of thermal, mechanical, and thermally self-healing properties via the DA reaction. In the PU capable of a DA reaction (DPU), characteristic peaks of DA and retro DA reactions were observed in the Fourier transform infrared (FT-IR) spectroscopy and endothermic peaks of retro DA reactions appeared in differential scanning calorimetry (DSC) thermograms. The DPU showed significantly enhanced physical properties and chemical resistance. The thermally self-healing capability was confirmed at 110 °C via the retro DA reactions. It is inferred that thermally self-healable crosslinked GNP/PU nanocomposites via DA reactions could be prepared in a simple bulk process through the molecular design of a chain extender for the in-situ reaction at the interface.
Highlights
Polymers in crosslinked structures offer considerable advantages such as improvements to heat and chemical resistance and mechanical strength
Much research has reported network polymers that are self-healable by stimuli and remendable based on the dynamic covalent bonds from Diels–Alder (DA) reaction adducts, disulfides, and imines under mild conditions [1,2,3]
Furfuryl compounds are generally used as a diene, and maleimide is used as a dienophile because it can be modified in various ways
Summary
Polymers in crosslinked structures offer considerable advantages such as improvements to heat and chemical resistance and mechanical strength. Haddon et al have recently reported that single-layer graphene can be used in DA and retro DA reactions as a dienophile or diene in combination with another reactant at various temperatures [11]. The commonly used interfacial tension relationships are those of Wu and Owen–Wendt given in Equations (1) and (2), respectively These formulas consider the dispersion and polar components of the surface tensions in accordance with the modified form of Fowke’s equations [20,21,22] as follows; γS−l. A concentrate of graphene-nanoplate (GNP) was obtained by dispersing GNP in a polyol for PU and the nanocomposites of PU and GNP were prepared via an in-situ DA reaction without any surface treatment of GNP. The interfacial tension between the materials was calculated so as to ensure that GNP was wet with the furfuryl compound and synthesized to enable the DA reaction with GNP without solvent. Thermally self-healing properties were noticed in the nanocomposites via retro DA reactions
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
