Kimberly M. Nelson

Template-Free Synthesis of Hierarchical Porous Metal-Organic Frameworks

A template-free synthesis of a hierarchical microporous-mesoporous metal-organic framework (MOF) of zinc(II) 2,5-dihydroxy-1,4-benzenedicarboxylate (Zn-MOF-74) is reported. The surface morphology and porosity of the bimodal materials can be modified by etching the pore walls with various synthesis solvents for different reaction times. This template-free strategy enables the preparation of stable frameworks with mesopores exceeding 15 nm, which was previously unattained in the synthesis of MOFs by the ligand-extension method.

Hypercrosslinked Phenolic Polymers with Well-Developed Mesoporous Frameworks†

A soft chemistry synthetic strategy based on a Friedel-Crafts alkylation reaction is developed for the textural engineering of phenolic resin (PR) with a robust mesoporous framework to avoid serious framework shrinkage and maximize retention of organic functional moieties. By taking advantage of the structural benefits of molecular bridges, the resultant sample maintains a bimodal micro-mesoporous architecture with well-preserved organic functional groups, which is effective for carbon capture. Moreover, this soft chemistry synthetic protocol can be further extended to nanotexture other arene-based polymers with robust frameworks.

Porous Liquids: A Promising Class of Media for Gas Separation

A porous liquid containing empty cavities has been successfully fabricated by surface engineering of hollow structures with suitable corona and canopy species. By taking advantage of the liquid-like polymeric matrices as a separation medium and the empty cavities as gas transport pathway, this unique porous liquid can function as a promising candidate for gas separation. Moreover, such a facile synthetic strategy can be further extended to the fabrication of other types of nanostructure-based porous liquid, opening up new opportunities for preparation of porous liquids with attractive properties for specific tasks.

Carbohydrate based hyper-crosslinked organic polymers with –OH functional groups for CO2 separation

Recently, microporous organic polymers, especially those hyper-crosslinked from functionalized aromatic monomers, have been shown to be effective for CO2 capture and storage with considerable capacity and selectivity. Herein, a class of novel microporous hyper-crosslinked polymers (HCPs), based on green and renewable carbohydrates, was synthesized by Friedel–Crafts alkylation for carbon capture and storage by hydrogen bonding and dipole–quadrupole interactions. These carbohydrate polymers, which have BET surface areas around 800 m2 g−1, can absorb a considerable amount of CO2 with the CO2/N2 selectivity up to 42 at 273 K, and 96 under 100 kPa in the mixed gases (0.15 mol CO2 and 0.85 mol N2). Furthermore, we experimentally and computationally studied the structures of carbohydrate backbones and determined several features that govern their CO2 absorption ability, which sheds light on understanding the structure/function relationship for designing better CO2 separation materials.

Membrane‐Based Gas Separation Accelerated by Hollow Nanosphere Architectures

The coupling of hollow carbon nanospheres with triblock copolymers is a promising strategy to fabricate mixed-matrix membranes. This is because the symmetric microporous shells combine with the hollow space to promote gas transport, and the unique soft-rigid molecular structure of triblock copolymers can accommodate a high loading of fillers without a significant loss of mechanical strength.

A renewable HSO3/H2PO3-grafted polyethylene fiber catalyst: an efficient heterogeneous catalyst for the synthesis of 5-hydroxymethylfurfural from fructose in water

Irradiation-induced co-grafting of acrylonitrile and vinylsulfonic acid (or vinylphosphonic acid) monomers on polyethylene fiber was studied for the heterogeneous catalysis of fructose dehydration into 5-hydroxymethylfurfural (HMF) solely in water. The acidic co-polymer exhibited excellent catalytic activity and maintained a high yield after being regenerated. We attribute these catalytic properties to a branched environment created by grafted chains, hydrophilic enough to interact with fructose in water but collectively dense enough to form a unique local phase mimicking organic solvents.

Directed Synthesis of Nanoporous Carbons from Task-Specific Ionic Liquid Precursors for the Adsorption of CO2

Postcombustion CO2 capture has become a key component of greenhouse-gas reduction as anthropogenic emissions continue to impact the environment. We report a one-step synthesis of porous carbon materials using a series of task-specific ionic liquids for the adsorption of CO2 . By varying the structure of the ionic liquid precursor, we were able to control pore architecture and surface functional groups of the carbon materials in this one-step synthesis process leading to adsorbents with high CO2 sorption capacities (up to 4.067 mmol g(-1) ) at 0 °C and 1 bar. Added nitrogen functional groups led to high CO2 /N2 adsorption-selectivity values ranging from 20 to 37 whereas simultaneously the interaction energy was enhanced relative to carbon materials with no added nitrogen.

A non-micellar synthesis of mesoporous carbon via spinodal decomposition

Mesoporous carbons were prepared via spinodal decomposition of non-amphiphilic linear polyethylene glycol with phloroglucinol–formaldehyde resin under refluxing acidic ethanol conditions. By shifting the molecular weight and the concentration of polyethylene glycol, both mesopore size and volume can be tuned.