Bitumen‐Like Polymers Prepared via Inverse Vulcanization with Shear Stiffening and Self‐Healing Abilities for Multifunctional Applications

Abstract

Bitumen, which is widely used in various applications, is facing the challenge of being unsustainable. Many strategies are proposed to recycle or replace bitumen. However, most of them can not address the unsustainability of bitumen from the roots. On the other hand, sulfur exists widely on the earth as a kind of industrial waste despite its extensive applications. Herein, a series of bitumen‐like polymers from elemental sulfur is obtained through an inverse vulcanization reaction. The sulfur‐containing polymers exhibit self‐healing, non‐toxic, and adjustable properties depending on the working environment. Based on these features, the applications of sulfur‐containing polymers in self‐healing waterproof sealants, impact‐resistance or shock‐absorption devices, and non‐Newtonian speed bumps are demonstrated. With the method of synthesizing multifunctional bitumen‐like polymers from sulfur wastes, a feasible way is provided to solve simultaneously the challenging problem of bitumen's unsustainability as well as sulfur's utilization, with the advantages including easy massed‐fabrication, non‐toxicity, extremely low cost (≈2 cents per gram) and environment friendliness.

Entropy-Driven Design of Highly Impact-Stiffening Supramolecular Polymer Networks with Salt-Bridge Hydrogen Bonds

“…Supramolecular polymer networks (SPNs), characterized by their highly dynamic cross-links, have emerged as a promising candidate for designing impact-stiffening materials. − Importantly, the kinetics of the transient physical interactions among supramolecular polymer chains are highly sensitive to strain rate, enabling the rapid soft-to-rigid transformation upon impact. , This strain rate dependence can be understood within a classical thermodynamic framework. As depicted in Figure a, the formation of typical physical interactions is often accompanied by an entropy penalty (loss of conformational entropy, Δ S < 0). − Based on the principle of time–temperature equivalency, the strain rate dependence of transient cross-links in SPNs can be effectively regulated by manipulating the entropy penalty (|Δ S |), which is the slope of the Gibbs free energy (Δ G )–temperature curve.…”