Molecular Modeling of Poly(methylmethacrylate-<i>block</i>-acrylonitrile) as Precursors of Porous Carbon Fibers

Porous carbon fibers (PCFs) based on block copolymers exhibit well-controlled hierarchical porous structures and high specific interfacial areas, which lead to excellent electrochemical properties. Understanding the conformation and morphology of polymer precursors before conversion is crucial for designing and optimizing PCFs. To expedite materials discovery, we perform molecular dynamic simulations for a series of poly(methylmethacrylate-block-acrylonitrile) (PMMA-b-PAN) with various block molecular weights and develop a model to characterize the morphology and compute the interfacial area of PMMA-b-PAN melts. We build both laminar and disordered phase of PMMA-b-PAN melts with an atomistic model of the polymer. For the disordered melts, our results show that the interfacial area is maximized when the volume fraction of either block is close to 50%, consistent with experimental results. The stability of the laminar phase is probed by performing thermal annealing on the systems and the conversion to a disordered phase is realized by introducing extra attractions between PAN blocks, which mimic the cross-linking reactions of PAN blocks in experiments. Our models pave the way of optimizing PCFs by designing PMMA-b-PAN precursors in silico.