Siwu Wu

An advanced elastomer with an unprecedented combination of excellent mechanical properties and high self-healing capability

Rubbers are widely applied in tires, seals, biomedical materials and aerospace applications because of their unique high elasticity. However, combining high self-healing capability and excellent mechanical performance in a rubber remains a formidable challenge. In this work, inspired by the energy dissipation mechanism and the recoverability of sacrificial bonds, the authors describe a dual-dynamic network design of a high-performance elastomer in which weaker multiple hydrogen bonds and stronger Zn–triazole coordination have been engineered into an unvulcanized cis-1,4-polyisoprene (IR) matrix. Accordingly, the elastomer obtains high tensile strength (21 MPa) and toughness (60 MJ m−3). The facilitated chain orientation in such a dual-dynamic network is finely substantiated by the molecular dynamics simulation results. Significantly, this dual-dynamic network design enables a fully cut elastomer to be healed at mild temperature. Under healing at 80 °C for 24 h, the healed elastomer regains excellent mechanical properties (tensile strength of 15.5 MPa and fracture energy of 42.8 MJ m−3). We envision that this design concept can not only develop a new network construction method in rubbers instead of vulcanization, but also provide inspiration for preparing advanced elastomers with the combination of excellent mechanical performance and high self-healing capability.

Elastic-resilience-induced dispersion of carbon nanotubes: a novel way of fabricating high performance elastomer

State-of-the-art processes cannot achieve rubber/multi-walled carbon nanotube (MWCNT) composites with satisfactory performance by using pristine MWCNTs and conventional processing equipment. In this work, high performance rubber/MWCNT composites featuring a combination of good mechanical properties, electrical and thermal conductivities and damping capacity over a wide temperature range are fabricated based on a well-developed master batch process. It is demonstrated that the MWCNTs are dispersed homogeneously due to the disentanglement induced by well-wetting and shearing, and the elastic-resilience-induced dispersion of the MWCNTs by rubber chains via the novel processing method. To further enhance the efficacy of elastic-resilience-induced dispersion for MWCNTs, a slightly pre-crosslinked network is constructed in the master batch. Consequently, we obtain rubber/MWCNT composites with unprecedented performance by amplifying the reinforcing effect of relatively low MWCNT loading. This work provides a novel insight into the fabrication of high performance functional elastomeric composites with pristine CNTs by taking advantage of the unique elastic resilience of rubber chains as the driving force for the disentanglement of CNTs.

Sustainable, recyclable and robust elastomers enabled by exchangeable interfacial cross-linking

Waste tire elastomers generate serious resource and environmental problems. Herein, a generic avenue was exploited by implementing exchangeable β-hydroxyl ester linkages between natural rubber and carbon black, which integrated covalent adaptable networks, mechanical robustness and reprocessability into a commercial rubber formulation by excluding the employment of toxic rubber additives.

Toughening Elastomers Using a Mussel-Inspired Multiphase Design

It is a challenge to simultaneously achieve high stretchability, high modulus, and recoverability of polymers. Inspired by the multiphase structure of mussel byssus cuticles, we circumvent this dilemma by introducing a deformable microphase-separated granule with rich coordination into a ductile rubber network. The granule can serve as an additional cross-link to improve the modulus, while the sacrificial, reversible coordination can dissociate and reconstruct continuously during stretching to dissipate energy. The elastomer with such a bioinspired multiphase structure exhibits over a 10-fold increase in toughness compared to the original sample. We envision that this work offers a novel yet facile biomimetic route toward high-performance elastomers.