Solid-supported amine-based polymers are known to be effective for CO2 capture from dilute streams, including flue gas and ambient air. In this work, we report the synthesis of well-defined poly­(glycidyl amine) (PGA) prepared via controlled anionic polymerization followed by postpolymerization modifications and demonstrate the use of PGA-loaded mesoporous silica (SBA-15) for CO2 capture from dilute streams (flue gas) as well as from ultradilute streams (direct air capture). A series of PGA materials with varied molecular weight (χ n = 15, 25, and 50) is synthesized via anionic ring-opening polymerization (ROP) and subsequent postpolymerization modifications. The resulting polymers are obtained with relatively narrow polydispersity and predetermined molecular weights. PGA is impregnated into mesoporous silica SBA-15 at different amine loadings (3–8 mmol of N/g of SiO2) and characterized by thermogravimetric analysis (TGA) and N2 physisorption techniques. The performance of the PGA/SBA-15 composites is investigated over a range of CO2 partial pressures and adsorption temperatures and compared to a benchmark material, branched poly­(ethylenimine) (PEI)/SBA-15. PGA shows trends in its CO2 capture performance that are different from PEI sorbents but similar to sorbents based on poly­(allylamine) (PAA), an oxygen-free analogue to PGA. The effect of oxidative treatment under simulated air (21% O2) for 24 h at 110 °C on the CO2 uptake performance is also evaluated, and PGA is shown to degrade less than PEI on a relative basis. Single-component water vapor sorption isotherms of PGA-loaded SBA-15 are generated at 35 °C and compared against branched PEI-loaded SBA-15 to assess material hydrophobicity. PGA is demonstrated to be a candidate polymer in amine/oxide hybrid CO2 sorbents.

Alkyl-aryl amine-rich small molecules (Ph-X-YY) are prepared by one-step nucleophilic substitution from tri- (X = 3) and hexa-bromine-substituted (X = 6) aromatic cores with two different aliphatic diamines, ethylenediamine (YY = ED) and propylenediamine (YY = PD). The resulting Ph-X-YY molecules are impregnated into mesoporous silica support materials (SBA-15) at predetermined organic loadings (20%–60%). TGA and DSC analyses suggest that these sorbent materials have good thermal stability. An increase in the amine loading led to an increase in CO2 adsorption capacity measured under simulated dry direct air capture (DAC) conditions. The Ph-3-YY based sorbents show superior CO2 adsorption capacities compared to the Ph-6-YY-based sorbent homologues, likely due to the bulkier molecular structure of the Ph-6-YY family. The highest CO2 capacity was demonstrated with the Ph-3-ED-based sorbent, 1.9 mmol/gSiO2, and an amine efficiency of 0.13 mmol CO2/mmol N at 35 °C under dry conditions. Temperature-swing adsorption/desorption cycles showed that the Ph-X-YY/SBA-15 had relatively stable performance that is comparable to that of the benchmark poly­(ethyleneimine) (PEI) and linear poly­(propyleneimine) (PPI) supported SBA-15 sorbents. The 60% Ph-3-ED/SBA-15 sample showed a 2-fold increase in the CO2 adsorption capacity under humid conditions (2.9 mmol/gSiO2 @ 30%, RH) and a 70% increase in amine efficieny (0.17 mmol CO2/mmol N). Thus, these aromatic-based polyamine molecules offer good potential for incorporation into practical CO2 sorbents targeting DAC technologies, and their structures expand the library of the amine-rich molecules that have been explored for DAC.

[2.2]Paracyclophane-1,9-dienes substituted with n-octyl chains have been synthesised from the corresponding dithia[3.3]paracyclophanes using a benzyne induced Stevens rearrangement. The use of 2-(trimethylsilyl)phenyl trifluoromethanesulfonate and tetra-n-butylammonium fluoride as the in situ benzyne source gave significantly improved yields over traditional sources of benzyne and enabled the preparation of n-octyl substituted [2.2]paracyclophane-1,9-dienes on a multi-gram scale.

The ring opening metathesis polymerisation (ROMP) of three n--octyl subsitutued [2.2]paracyclophane--1,9--dienes, initiated by Grubbs ruthenium carbene complexes is reported. The molecular weight of the resulting alkyl--subsituted poly(p--phenylene vinylene)s is determined by the monomer to initiator ratio and the polymers are isolated with relatively narrow polydispersities and control of the end groups. Only the pseudo--geminal isomer of the tetra--alkyl subsitutued [2.2]paracyclophane--1,9--diene was susceptible to ROMP. The optical properties of the two series of polymers was investigated.

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