A general strategy to prepare macro-/mesoporous materials from thermoplastic elastomer blends

Abstract

Hierarchically macro-/mesoporous (HMM) materials generally contain at least two distinct populations of pore sizes with ranges of 2–50 nm and >50 nm; they exhibit promising performance for various applications, such as water remediation and energy storage, due to the combined advantages of high surface area, pore accessibility, and porosity. Conventional synthesis of HMM materials typically utilize multiple templating agents to develop varied sizes of pores, often involving complex processes and the use of relatively expensive precursors with low recourse-efficiency, leading to significant challenges toward scaled production. Therefore, development of a simple approach for HMM materials synthesis is important for facilitating their commercialization and broad use. In this work, we demonstrate a generalizable method for the fabrication of HMM polymers and carbons using immiscible thermoplastic elastomer (TPE) blends, through incorporating a small amount of polystyrene-block-polyisoprene-block-polystyrene (SIS) within the matrix of polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS), followed by sulfonation-induced crosslinking. During this reaction, the presence of SIS not only leads to the formation of macropores from released gaseous products, but it also facilitates the selective degradation of polystyrene domains to develop ordered mesopores. These porous polymers can then be converted to HMM carbons upon pyrolysis, where ordered nanostructures can be retained. This approach to produce HMM materials can be generalized to different selections of TPE blends with varied precursor identity and molecular weight. Furthermore, we demonstrate that HMM polymers can be employed as sorbents for the efficient removal of heavy metals from aqueous systems, while their derived carbons are efficient for organic pollutant remediation. We believe this work demonstrates a simple and robust approach with great potential for the scaled manufacturing of HMM materials to enable their broad use in practical applications.