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  1. Free, publicly-accessible full text available December 1, 2024
  2. Abstract

    Despite groundbreaking advances in the additive manufacturing of polymers, metals, and ceramics, scaled and accurate production of structured carbons remains largely underdeveloped. This work reports a simple method to produce complex carbon materials with very low dimensional shrinkage from printed to carbonized state (less than 4%), using commercially available polypropylene precursors and a fused filament fabrication-based process. The control of macrostructural retention is enabled by the inclusion of fiber fillers regardless of the crosslinking degree of the polypropylene matrix, providing a significant advantage to directly control the density, porosity, and mechanical properties of 3D printed carbons. Using the same printed plastic precursors, different mechanical responses of derived carbons can be obtained, notably from stiff to highly compressible. This report harnesses the power of additive manufacturing for producing carbons with accurately controlled structure and properties, while enabling great opportunities for various applications.

     
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  3. Free, publicly-accessible full text available October 27, 2024
  4. The production of ordered mesoporous carbons (OMCs) can be achieved by direct pyrolysis of self-assembled polymers. Typically, these systems require a majority phase capable of producing carbon, and a minority phase to form pores through a thermal decomposition step. While polyacrylonitrile (PAN)-based block copolymers (BCPs) have been broadly reported as OMC precursors, these materials have a relatively narrow processing window for developing ordered nanostructures and often require sophisticated chemistry for BCP synthesis, followed by long crosslinking times at high temperatures. Alternatively, olefinic thermoplastic elastomers (TPEs) can be convered to large-pore OMCs after two steps of sulfonation-induced crosslinking and carbonization. Building on this platform, this work focuses on the precursor design concept for the efficient synthesis of OMCs through employing low-cost and widely available polystyrene-block-polybutadiene-block-polystyrene (SBS), which contains unsaturated bonds along the polymer backbone. As a result, the presence of alkene groups greatly enhances the kinetics of sulfonation-induced crosslinking reaction, which can be completed within only 20 min at 150 °C, nearly an order of magnitude faster than a recently reported TPE system containing a fully saturated polymer backbone. The crosslinking reaction enables the production of OMCs with pore sizes (∼9.5 nm) larger than most conventional soft-templating systems, while also doping sulfur heteroatoms into the carbon framework of the final products. This work demonstrates efficient synthesis of OMCs from TPE precursors which have a great potential for scaled production, and the resulting products may have broad applications such as for drug delivery and energy storage. 
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    Free, publicly-accessible full text available August 29, 2024
  5. Free, publicly-accessible full text available August 25, 2024
  6. 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.

     
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  7. Abstract

    Controlling the self‐assembly behaviors of block copolymers (BCPs) is a focal point of many research thrusts due to their broad use in various applications. While BCP molecular weight, volume fraction, and chemical identities are key thermodynamic parameters to determine their morphology, an emergent method in this area is through reaction‐induced changes to the characteristics of a BCPin situ, which provides access to multiple morphologies and domain sizes from a single parent polymer, as well as enabling the formation of metastable morphologies which may be difficult to attain otherwise. This work provides a focused review about the current state of reaction‐induced morphology control in BCPs in both solution and solid states. Furthermore, we provide a forward‐looking perspective on the future opportunities of understanding and employing reaction engineering to manipulate and advance BCP self‐assembly. © 2023 Society of Industrial Chemistry.

     
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  8. Abstract Leveraging computational resources for modern physics education has become increasingly prevalent, especially catalyzed by the COVID-19 pandemic when distance learning is widely implemented. Herein, we report an open-source software for students and instructors to on-demand simulate optical reflection behaviors of one-dimensional photonic crystals (1D-PCs), a model system for understanding light–matter interactions relevant to materials science and optical physics. Specifically, our MATLAB application, ReflectSim, employs an adapted transfer matrix method simulation and can account for the effects of several critical material design parameters, including interfacial roughness and layer geometry, to determine the reflectance spectrum of user-defined 1D-PCs. By packing our codes into a graphical user interface, this software is simple to use and bypass the requirement of any coding experiences from users, which can be widely used as an education tool in high school/undergraduate classrooms and K-12 outreach activities. We believe that ReflectSim provides great potential for assisting students in understanding optical phenomenon in nanostructured layered materials and relevant scientific concepts through enabling more engaging learning experiences. 
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