Colin D. Wood

Lithiated Porous Aromatic Frameworks with Exceptional Gas Storage Capacity

Kristina Konstas, James W. Taylor, Aaron W. Thornton, Cara M. Doherty, Wei Xian Lim, Timothy J. Bastow, Danielle F. Kennedy, Colin D. Wood, Barry J. Cox, James M. Hill, Anita J. Hill, Matthew R. Hill

Solution-processable hypercrosslinked polymers by low cost strategies: a promising platform for gas storage and separation

The preparation of soluble microporous polymers for large-scale gas storage and separation with low cost, scalability and synthetic diversification is extremely challenging. Here, we report the synthesis of solution-processable hypercrosslinked polymers (SHCPs) by folding polystyrene molecules at high dilution. A low cost knitting method is employed and by slowly adding an external crosslinker, intramolecular cross-links were introduced. Despite being highly cross-linked, the resulting hypercrosslinked polymers dissolve in a range of organic solvents to form thermodynamically stable homogenous liquids. By increasing the concentration of polystyrene and the amount of crosslinker, the BET surface area of SHCPs increased with the largest surface area of 724 m2 g−1. Moreover, they also show comparable gas uptake properties reaching 8.11 wt% CO2 adsorption (1.13 bar and 273 K), 1.01 wt% H2 adsorption (1.13 bar and 77 K), and 0.14 wt% CH4 adsorption (1.13 bar and 273 K). The reaction offers a route to new classes of solution-processable microporous polymers as promising materials for gas storage and separation.

Hierarchical Porous Polystyrene Monoliths from PolyHIPE

Hierarchical porous polystyrene monoliths (HCP-PolyHIPE) are obtained by hypercrosslinking poly(styrene-divinylbenzene) monoliths prepared by polymerization of high internal phase emulsions (PolyHIPEs). The hypercrosslinking is achieved using an approach known as knitting which employs formaldehyde dimethyl acetal (FDA) as an external crosslinker. Scanning electron microscopy (SEM) confirms that the macroporous structure in the original monolith is retained during the knitting process. By increasing the amount of divinylbenzene (DVB) in PolyHIPE, the BET surface area and pore volume of the HCP-PolyHIPE decrease, while the micropore size increases. BET surface areas of 196-595 m(2) g(-1) are obtained. The presence of micropores, mesopores, and macropores is confirmed from the pore size distribution. With a hierarchical porous structure, the monoliths reveal comparable gas sorption properties and potential applications in oil spill clean-up.

Hyper-Cross-Linked Additives that Impede Aging and Enhance Permeability in Thin Polyacetylene Films for Organic Solvent Nanofiltration

Membrane materials with high permeability to solvents while rejecting dissolved contaminants are crucial to lowering the energy costs associated with liquid separations. However, the current lack of stable high-permeability materials require innovative engineering solutions to yield high-performance, thin membranes using stable polymers with low permeabilities. Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) is one of the most permeable polymers but is extremely susceptible to physical aging. Despite recent developments in anti-aging polymer membranes, this research breakthrough has yet to be demonstrated on thin PTMSP films supported on porous polymer substrates, a crucial step toward commercializing anti-aging membranes for industrial applications. Here we report the development of scalable, thin film nanocomposite membranes supported on polymer substrates that are resistant to physical aging while having high permeabilities to alcohols. The selective layer is made up of PTMSP and nanoporous polymeric additives. The nanoporous additives provide additional passageways to solvents, enhancing the high permeability of the PTMSP materials further. Through intercalation of polyacetylene chains into the sub-nm pores of organic additives, physical aging in the consequent was significantly hindered in continuous long-term operation. Remarkably we also demonstrate that the additives enhance both membrane permeability and rejection of dissolved contaminants across the membranes, as ethanol permeability at 5.5 × 10-6 L m m-2 h-1 bar-1 with 93% Rose Bengal (1017.6 g mol-1) rejection, drastically outperforming commercial and state-of-the-art membranes. These membranes can replace energy-intensive separation processes such as distillation, lowering operation costs in well-established pharmaceutical production processes.

Organic Microporous Nanofillers with Unique Alcohol Affinity for Superior Ethanol Recovery toward Sustainable Biofuels

To minimize energy consumption and carbon footprints, pervaporation membranes are fast becoming the preferred technology for alcohol recovery. However, this approach is confined to small-scale operations, as the flux of standard rubbery polymer membranes remain insufficient to process large solvent volumes, whereas membrane separations that use glassy polymer membranes are prone to physical aging. This study concerns how the alcohol affinity and intrinsic porosity of networked, organic, microporous polymers can simultaneously reduce physical aging and drastically enhance both flux and selectivity of a super glassy polymer, poly-[1-(trimethylsilyl)propyne] (PTMSP). Slight loss in alcohol transportation channels in PTMSP is compensated by the alcohol affinity of the microporous polymers. Even after continuous exposure to aqueous solutions of alcohols, PTMSP pervaporation membranes loaded with the microporous polymers outperform the state-of-the-art and commercial pervaporation membranes.

CO2 capture by amine infused hydrogels (AIHs)

We report a proof-of-concept study on an entirely new class of CO2 absorbent which is prepared by simply adding commercially available hydrogels into organic amine solutions to generate amine infused hydrogels (AIHs). The hydrogel ensures that the CO2–amine reactions are maintained in AIHs but the interfacial area/kinetics for these interactions is significantly increased. As a result, this new material rapidly captures CO2 with higher overall uptake compared to the commonly used aqueous amine solutions under similar experimental conditions. It reaches exceptional CO2 uptake without the need for stirring. In terms of recycling, the absorption capacity of AIHs is well maintained after multiple regeneration cycles if high molecular weight amines and a suitable hydrogel are applied. Moreover, the hydrogel can easily be recovered and reused, noticeably reducing material costs. In all, this proof-of-concept study demonstrates that by using an inexpensive and readily available material (hydrogel), AIHs show promise as a CO2 absorbent.

A Highly Tunable Approach to Enhance CO2 Capture with Liquid Alkali/amines

A diverse range of alkali/amine infused hydrogels (AIHs) were generated by incorporating the liquids into a hydrogel particle for carbon capture application. As a consequence, the CO2 uptake was significantly enhanced owing to the increased contact area. This AIHs technique was highly tunable as it could be applicable to varying species of alkali chemicals and it was found that their molecular structure and architectures could impact the CO2 uptake. Compared to stirred bulk alkali/amine solutions, the CO2 absorption capacity of AIHs was increased by 400% within 30 min with a low hydrogel loading (10 w/w%). In addition, the recyclability of various AIHs was assessed and was found to be extremely encouraging. The effect of salinity on the performance of AIHs was also investigated and high salinity was found to have a minimal effect on CO2 absorption. Most importantly, the preparation of AIHs is fast and straightforward with few wastes and byproducts formed in the preparation process. In all, extensive investigations were presented and the AIHs were found to be a highly tunable and effective approach to enhance CO2 capture with liquid alkali/amines.