Smart slippery liquid-infused porous surfaces (SLIPSs) have aroused remarkable attention owing to tremendous application foreground in biomedical instruments and industry. However, challenges still remain in fabricating durable SLIPSs. In this work, a fast and highly efficient self-repairing slippery surface (SPU-60M) was fabricated based on a polyurethane membrane and silicone oil. By introducing a great quantity of reversible disulfide bonds into the polymer backbone and hydrogen bonds in the polymer interchain, this SLIPS material could be quickly repaired in 15 min with 97.8% healing efficiency. Moreover, the self-healing efficiency could be maintained at 42.75% after the 10th cutting–healing cycle. Notably, SPU-60M showed excellent self-repairing ability not only in an ambient environment but also in an underwater environment and at ultralow temperatures. Besides, the icing delay time (DT) of SPU-60M could be prolonged to 1182 s at −15 °C, and the ice adhesion strength was only 10.33 kPa at −30 °C. In addition, SPU-60M had excellent anti-fouling performance with BSA adsorption of 2.41 μg/cm2 and Escherichia coli CFU counts of 41 × 104. These findings provide a facile way to design highly efficient self-repairing SLIPSs with multifunctionality.
Rubber materials are frequently degraded by environmental factors such as light, heat and oxygen during service. Conventional protective approaches, however, often involve adding antioxidants during processing, which not only causes significant environmental pollution but also limits the applicability of rubber products in the biomedical field. Therefore, developing robust aging mitigation strategies constitutes a critical imperative to ensure material longevity. This study proposes a feasible and effective strategy: inducing network rearrangement in rubber through pre-stretching to achieve a more stable crosslinked structure, thereby enhancing its thermo-oxidative stability. During vulcanization, polysulfide and disulfide bonds are formed in the crosslinking network of rubber. Pre-stretching preferentially broke weaker bonds, inducing the conversion of polysulfide bonds to disulfide bonds during the stretching process. This strain-induced network rearrangement enhanced the rigidity and stability of rubber. At elevated temperatures, this mechanism became more pronounced. Pre-stretching triggered rapid conversion of polysulfide to disulfide bonds during the initial stages of thermo-oxidative aging. Given the higher bond energy and stability of disulfide bonds under thermal-oxidative conditions, the aging resistance of rubber is significantly improved. Both atomic force microscopy tests and mechanical tests demonstrated that stretching induced dynamic transformation of sulfur bonds in the crosslinking network, leading to significant changes in spatial heterogeneity under thermo-oxidative conditions. As a result, the thermo-oxidative resistance of natural rubber was enhanced, with the retention of tensile strength increasing from 58.6 % to 81.1 % after 24 h of thermo-oxidative aging. This study not only provided important guidance for the general design of thermo-oxidation-resistant elastomers but also advanced the understanding of rubber network evolution mechanisms under thermo-mechanical coupling conditions.
Sulfur-containing dynamic polymers had attracted significant attention due to their unique chemical structures with high reversibility. Utilizating sulfur, an inexpensive industrial waste product, to synthesize dynamic polysulfide polymers through reverse vulcanization has been a notable approach. However, this method required high temperatures and resulted in the release of unpleasant oders. In this study, we presented a robust method for the preparation of sulfur-rich polymers with dynamic polysulfide bonds from elemental sulfur and inexpensive epoxide monomers via a one-pot strategy at the mild room temperature. Different types of polysulfide molecules and polymers were synthesized by reacting various epoxide compounds with sulfur, along with the investigation of their structures and dynamic behaviors. It was noteworthy that the obatined polymers prepared from m -(2,3-epoxypropoxy)- N,N -bis(2,3-epoxypropyl)aniline and elemental sulfur exhibit multiple dynamic behaviors, including polysulfide metathesis and polysulfide-thiol exchange, enabling their rapid stress relaxation, self-healing, reprocessing and degradable properties of the cross-linked polymer. More importantly, the hydroxyl groups at the side chains from epoxide ring opening exhibited potential transesterification. This work provided a facile strategy for designing dynamic sulfur-rich polymers via a mild synthesis route.
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