Direct synthesis of ordered mesoporous materials from thermoplastic elastomers

Abstract

The ability to manufacture ordered mesoporous materials using low-cost precursors and scalable processes is essential for unlocking their enormous potential to enable advancement in nanotechnology. While templating-based methods play a central role in the development of mesoporous materials, several limitations exist in conventional system design, including cost, volatile solvent consumption, and attainable pore sizes from commercial templating agents. This work pioneers a new manufacturing platform for producing ordered mesoporous materials through direct pyrolysis of crosslinked thermoplastic elastomer-based block copolymers. Specifically, olefinic majority phases are selectively crosslinked through sulfonation reactions and subsequently converted to carbon, while the minority block can be decomposed to form ordered mesopores. We demonstrate that this process can be extended to different polymer precursors for synthesizing mesoporous polymer, carbon, and silica. Furthermore, the obtained carbons possess large mesopores, sulfur-doped carbon framework, with tailorable pore textures upon varying the precursor identities.

Fig. 1. Sulfonation-induced crosslinking reaction of SEBS.

a Schematic illustration of thermoplastic elastomer undergoing a sulfonation induced crosslinking reaction and being converted into a carbon precursor. The precursor is pyrolyzed in inert atmospheres to produce mesoporous products. b Crosslinking reaction schemes for both PEB and PS blocks of the SEBS118 precursor. c Plot of mass gain and gel fraction of the SEBS118 polymer as a function of sulfonation reaction time. d FTIR spectra of SEBS118 as a function of sulfonation time. e SAXS patterns of SEBS118 as a function of crosslinking time at 150 °C. Source data are provided as a Source Data file.

Fig. 2. Conversion of SEBS to ordered mesoporous materials through pyrolysis.

a TGA results up to 800 °C in N₂ atmosphere for neat SEBS118, sulfonated homopolymer polystyrene, and crosslinked SEBS118. b FTIR spectra of neat SEBS118, calcinated SEBS118, and the carbonized product. Source data are provided as a Source Data file.

Fig. 3. Characterization of SEBS-derived ordered mesoporous materials.

a SAXS patterns for ordered mesoporous polymer and SEBS118-derived OMC carbonized at 800 °C, 1000 °C, 1200 °C. b Nitrogen adsorption isotherms which exhibit type IV isotherms, indicating the presence of mesopores. For clarity, the isotherms have been shifted in the positive Y-direction. c Pore width calculated through NLDFT models for carbon slit pores at 77 K and the Brunauer-Emmett-Teller (BET) surface area at each carbonization temperature. d XPS survey scans of each material indicating the presence of oxygen and sulfur atoms doped within the carbon framework. The inset sulfur content is provided in at%. SEM micrographs of (e) mesoporous polymer and mesoporous carbon carbonized at (f) 800 °C, (g) 1000 °C, (h) 1200 °C. Source data are provided as a Source Data file.

Fig. 4. Characterization of OMCs-derived from multiple precursors.

a SAXS profile, (b) nitrogen sorption isotherm, (c) pore size distribution and (d) SEM image of OMC pyrolyzed from SEBS89. e SAXS profile, (f) nitrogen sorption isotherm, (g) pore size distribution and (h) SEM image of OMC produced from SEBS100. i SAXS profile, (j) nitrogen sorption isotherm, (k) pore size distribution and (l) SEM image of OMC produced from SEBS130. Source data are provided as a Source Data file.

Fig. 5. Synthesis of OMS from SEBS-derived OMC templates.

a Schematic illustration of OMS synthesis where OMCs are infiltrated with a silica precursor which is then aged. After aging, the template is removed by exposure to high temperatures in air, resulting in mesoporous silica. (b) SAXS pattern, (c) nitrogen adsorption/desorption isotherm, (d) pore size distribution, and (e) SEM image of OMS derived from using SEBS118–800 OMC as hard templates. Source data are provided as a Source Data file.