Healable and reprocessable silica/poly(oxime‐urethane) composite elastomer with high mechanical robustness and exceptional damage‐tolerant capacity

Abstract

A new generation of elastomer is expected to incorporate exceptional healing, reprocessing, damage-tolerant capacity and outstanding strength and toughness in view of a sustainable society. To search a suitable method to perfectly match the overall performance is yet a formidable challenge. Here, a thermaltriggered self-healing polyurethane composite elastomer was fabricated by crosslinking isocyanate terminated polyurethane with amidoxime-modified silica particles. The rigid fillers (silica particles) can effectively dissipate energy under an external force. The prepared particles and elastomer were detailly characterized by various instruments. The developed elastomer (POUs@2SiPs) had great tensile strength (39.47 MPa), decent elongation at break (1056.51%), excellent toughness (170.58 MJ m À3 ) and outstanding fracture energy (81.14 KJ m À2 ). Meanwhile, the well-designed healing capability enabled the material to regain its original mechanical performance and integrity after damage. In addition, the reprocessibility granted material reusability to extend the service lifespan. This work is supposed to provide a meaningful strategy for developing the elastomer, which can effectively balance those conflict properties of mechanical strength, damage-tolerant capacity and self-healing.

Covalent adaptive networks with repairable, reprocessable, reconfigurable, recyclable, and re-adhesive (5R) performance via dynamic isocyanate chemistry

“…141 Silica nanoparticles can be incorporated into a poly(oxime-urethane) elastomer to develop damage-tolerant self-healing composites. 142 The examples stated above demonstrate that the dissociation reaction of oxime-urethane moieties can be finely adjusted by changing the segment flexibility or introducing metal coordination. Also, the derived reparable polymers can be thermosets or elastomers with a repair temperature spanning from room temperature to >100 °C.…”

Dynamic covalent polymers enabled by reversible isocyanate chemistry

“…Then, urethanation with HDI led to polyamide CANs, in which reprocessing properties and shape memory effects were demonstrated. 132 OUB-based composites were engineered with different fillers to obtain the combination between dynamicity and mechanical robustness 133,134 or conductivity. 135 For instance, reactivated silica particles with surface oxime groups were used as crosslinkers for the construction of reprocessable PU composites and it was found that the homogeneous dispersion of silica fillers in the polymer matrix increased the material toughness due to the enhanced microphase separation.…”

“…135 For instance, reactivated silica particles with surface oxime groups were used as crosslinkers for the construction of reprocessable PU composites and it was found that the homogeneous dispersion of silica fillers in the polymer matrix increased the material toughness due to the enhanced microphase separation. 134 Implanting graphene as hard domains into POU CANs could reinforce the mechanical strength and gave stretchable self-healing conductors for applications such as flexible electronics and wearable sensors. 135 Besides these utilizations in crosslinked polymers, the decreased viscosity of polymers when OUBs are activated allows access to the melt processing of high molecular weight polymers, which are liable to degradation at high processing temperatures.…”

High‐performance healable plastics: Focusing topological structure design based on constitutional dynamic chemistry

“…In the development of healable polymeric systems, mechanical robustness (durability) and dynamic functions (reversibility, disassembly, and healability) are often contradictory requirements (Figure 1B). [61][62][63][64][65][66][67][68][69][70] Thus, it presents a formidable task to impart robust plastics with the capacity F I G U R E 1 (A) Tree diagram of types of plastics, where healable plastics have the potential to mitigate the issue of white pollution with minimal human intervention. (B) Challenges in the fabrication of healable plastics: inherent conflict between dynamics and mechanical robustness.…”

“…In the development of healable polymeric systems, mechanical robustness (durability) and dynamic functions (reversibility, disassembly, and healability) are often contradictory requirements (Figure 1B). 61–70 Thus, it presents a formidable task to impart robust plastics with the capacity to heal, which is derived from their frozen polymer networks crosslinked by permanent covalent bonds. In general, the exploitation of thermodynamically stable yet kinetically labile interactions to replace the common covalent bonds is a prerequisite to develop healable plastics.…”