(499g) Leveraging Reaction-Induced Nanostructural Evolution of Thermoplastic Elastomer Precursors for Ordered Mesoporous Material Synthesis

Block copolymer (BCP) self-assembly has been key in the development of nanotechnologies for applications including solid electrolytes, nanopatterning, and gas/liquid separations among many others. The thermodynamic drive for BCPs to assemble into well-ordered nanostructures is also indispensable for synthesizing new nanostructured products such as ordered mesoporous materials. Selective thermal degradation of the minority domains within a polyacrylonitrile (PAN)- derived BCP through pyrolysis has been demonstrated as a simple, efficient method to produce ordered mesoporous materials. However, this typically necessitates a high temperature thermal stabilization of a polyacrylonitrile majority phase, within the solid-state, which can decrease order in the final pore structure, and precursor synthesis could be challenging to achieve at large scales. This work demonstrates the use of commodity, styrenic thermoplastic elastomers as precursors for ordered mesoporous material synthesis through a heterogeneous sulfonation-induced crosslinking reaction of the majority segments, enabling the production of ordered mesoporous carbons at high temperatures. The sulfonation-crosslinking process results in distinct simultaneous reactions within the majority and minority phases of the BCP precursor. The complex interplay between these reactions dictates the evolution of the nanostructure throughout the crosslinking process and, consequently, the pore texture of the material after pyrolysis. Understanding these self-assembly behaviors under non-equilibrium processing, along with the versatility of the process to other thermoplastic elastomer precursors, provides the opportunity to tune the pore textures of the desired materials with pore sizes across the mesopore range to target material properties for many applications.