Encapsulation of Nanoparticle Organic Hybrid Materials within Electrospun Hydrophobic Polymer/Ceramic Fibers for Enhanced CO₂ Capture

Abstract

Liquid‐like nanoparticle organic hybrid materials (NOHMs) consisting of a silica core with ionically grafted branched polyethyleneimine chains (referred to as NIPEI) are encapsulated within submicron‐scale polyacrylonitrile (PAN)/polymer‐derived‐ceramic electrospun fibers. The addition of a room‐temperature curable, liquid‐phase organopolysilazane (OPSZ) ceramic precursor to the PAN/NOHM solution enhances the internal dispersion of NOHMs and forms a thin ceramic sheath layer on the fiber exterior, shielding the hydrophilic NIPEI to produce near‐superhydrophobic non‐woven fiber mats with contact angles exceeding 140°. 60:40 loadings of NOHMs to PAN/OPSZ can be reliably achieved with low OPSZ percentages required, and up to 4:1 NOHM:polymer loadings are possible before losing hydrophobicity. These fibers demonstrate up to ≈2 mmol CO2 g−1 fiber capture capacities in a pure CO2 atmosphere through the nonwoven fibrous networks and the permeability of the OPSZ shell. The hybrid fibers additionally show enhanced capture kinetics under pure CO2 and 400 ppm CO2 conditions, indicating their promising application as a direct air capture platform.

Perspectives from the 2022 Cohort of the American Chemical Society Summer School on Green Chemistry & Sustainable Energy

“…Some of this work is focused on decreasing energy consumption (addressing Green Chemistry Principle #6), through water-stable metal–organic frameworks (MOFs) production and encapsulation via hydrophobic materials to prevent the destruction of the crystal structure of MOFs for CO 2 capture applications . Other work includes a gas-assisted electrospinning encapsulation technique of nanoparticle organic hybrid materials (NOHMs), which are less volatile amine-based materials with polymer/ceramic materials to enhance their capture kinetics and to protect NOHMs from water uptake . Further work has focused on the synthesis of complex compounds from renewable sources by using an autocatalytic approach of O -formylation of alcohols, in which formic acid acts as a catalyst and reaction yields improve in every cycle of reuse of the solvent and the acid, addressing Green Chemistry Principle #2 related to improving atom economy (the catalyst is a byproduct of the reaction) and preventing waste when it is recycled (Principle #1).…”

“…15 Other work includes a gas-assisted electrospinning encapsulation technique of nanoparticle organic hybrid materials (NOHMs), which are less volatile amine-based materials with polymer/ceramic materials to enhance their capture kinetics and to protect NOHMs from water uptake. 16 Further work has focused on the synthesis of complex compounds from renewable sources by using an autocatalytic approach of O-formylation of alcohols, in which formic acid acts as a catalyst and reaction yields improve in every cycle of reuse of the solvent and the acid, 17 addressing Green Chemistry Principle #2 related to improving atom economy (the catalyst is a byproduct of the reaction) and preventing waste when it is recycled (Principle #1). These CCU technologies are still under development and require further incorporation of green chemistry approaches (Table 1), innovation, and best practices for community engagement in the locations where pressurized CO 2 may be transported and/or injected into the ground for storage in order for CCU to be more sustainable.…”