Sulfonation-Induced Cross-Linking and Nanostructural Evolution of a Thermoplastic Elastomer for Ordered Mesoporous Carbon Synthesis: A Mechanistic Study
Sulfonation-Induced Cross-Linking and Nanostructural Evolution of a Thermoplastic Elastomer for Ordered Mesoporous Carbon Synthesis: A Mechanistic Study
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DOI：
10.1021/acsaenm.3c00359
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发表时间：
2023-09
期刊：
影响因子：
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通讯作者：
M. Robertson;Andrew Barbour;Anthony Griffin;Alejandro Guillen Obando;Paul Smith;Zhe Qiang
中科院分区：
文献类型：
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作者：
M. Robertson;Andrew Barbour;Anthony Griffin;Alejandro Guillen Obando;Paul Smith;Zhe Qiang
自组装嵌段共聚物（bcp）的直接热解是一种资源高效的合成有序介孔碳（OMCs）的方法，通过这种方法得到的孔隙结构和性质通常由前驱体特性和加工途径共同决定。该领域以前的工作严重依赖于使用基于聚丙烯腈的BCP系统，该系统采用高温交联反应，可以影响其纳米结构的有序程度。最近，热塑性弹性体被用作新兴的OMC前驱体，如商品级聚苯乙烯-嵌段聚（乙烯-丁烯）-嵌段聚苯乙烯（SEBS）。该方法需要固体磺化诱导交联，涉及与大多数聚（乙烯-对丁烯）相和聚苯乙烯段同时发生反应。这项工作阐明了反应机制和条件如何控制SEBS纳米结构发展的基本原理，从而消除了磺化和交联的不同贡献。具体来说，小角度x射线散射结果，结合化学演化研究，表明聚苯乙烯磺化是增加畴间距的主要原因，这是通过热力学驱动的纳米结构重排和交联的动力学捕获之间的竞争介导的。研究了在不同反应条件下得到的交联SEBS转化为OMCs的过程，建立了关键的工艺结构关系。这些基本认识为通过磺化诱导交联和直接热解两步制备sebs衍生omc的合理体系设计提供了关键见解。
Direct pyrolysis of self-assembled block copolymers (BCPs) is a resource-efficient method for synthesizing ordered mesoporous carbons (OMCs), through which the resulting pore textures and properties are often collectively determined by the precursor identity and processing pathways. Previous works in this area heavily rely on the use of polyacrylonitrile-based BCP systems, which employ a high-temperature cross-linking reaction that can impact the degree of ordering in their nanostructures. Recently, thermoplastic elastomers have been employed as an emerging OMC precursor, demonstrated by commodity grade polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS). This method requires solid-state, sulfonation-induced cross-linking, involving simultaneous reactions with both the majority poly(ethylene-ran-butylene) phase and the polystyrene segments. This work elucidates the fundamentals of how the reaction mechanism and condition govern SEBS nanostructure development, which deconvolutes distinct contributions from sulfonation and cross-linking. Specifically, small-angle X-ray scattering results, in conjunction with chemical evolution investigations, indicate that polystyrene sulfonation is primarily responsible for increased domain spacing that is mediated through competition between thermodynamically driven nanostructure rearrangement and kinetic trapping from cross-linking. The conversion of cross-linked SEBS, obtained from varying reaction conditions, to OMCs is also studied for establishing critical process–structure relationship. These fundamental understandings provide key insights about rational system design of SEBS-derived OMCs, prepared through two steps of sulfonation-induced cross-linking and direct pyrolysis.