Microporous Hyper‐Cross‐Linked Polymers with High and Tuneable Content of Pyridine Units: Synthesis and Application for Reversible Sorption of Water and Carbon Dioxide

Abstract

New hyper‐cross‐linked porous organic polymers (POPs) with a high content of pyridine segments (7.86 mmol pyridine g−1), and a micro/mesoporous texture are reported. The networks are achieved by the chain‐growth homopolymerization of 2,6‐ and 3,5‐diethynylpyridines. The pyridine segments form links interconnecting the polyacetylene main chains in these networks. The content of pyridine segments in the networks can be tuned by copolymerizing diethynylpyridines with 1,3‐diethynylbenzene. The pyridine rings in the networks serve as base and hydrophilic centers for the sorption of CO2 and water. The homopolymer pyridine networks are highly efficient in the low‐pressure adsorption/desorption of CO2. This sorption mode is promising for the postcombustion removal of CO2 from the fuel gas. The poly(3,5‐diethynylpyridine) network exhibits high efficiency in capturing and releasing water vapor (determined capacity 376 mg g−1 at 298 K and relative humidity (RH) = 90% is one of the highest values reported for POPs) and is a promising material for the cyclic water harvesting from air. The reported networks are characterized by 13C cross‐polarization magic angle spinning NMR, thermogravimetric analysis, and N2 adsorption/desorption and their efficiency in CO2 and H2O capturing is discussed in relation to the content and type of incorporated pyridine segments.

Combining Polymerization and Templating toward Hyper-Cross-Linked Poly(propargyl aldehyde)s and Poly(propargyl alcohol)s for Reversible H2O and CO2 Capture and Construction of Porous Chiral Networks

“…Values of a H2ORH90 up to 420 mg/g (297 K) were achieved on POPs with epoxy functional groups [ 57 ]. Pyridine containing hyper-cross-linked POPs reported recently by our group exhibited a H2ORH90 up to 376 mg/g [ 17 ]. Water capture capacity of about 550 mg/g, (RH = 90%, 297 K) was reported for ionic POPs with quaternized 1,4-diazabicyclo[2.2.2]octane-type units [ 20 ].…”

“…All 13 C cross-polarization magic angle spinning (CP/MAS) NMR spectra were measured at 11.7 T using a Bruker Avance III 500 WB/US NMR spectrometer (Bruker Corporation, Billerica, MA, USA), as described elsewhere [ 17 ].…”

“…The adsorption/desorption isotherms of nitrogen (at 77 K) and CO 2 (at a range from 273 to 333 K) were measured at a Triflex V4.02 apparatus (Micromeritics Instrument Corporation, Norcross, GA, USA). Prior to the sorption measurements, all the samples were degassed using Micromeritics SmartVacPrep instrument as described previously [ 17 ].…”

“…For example, POPs containing various acid and base groups, covalently inbuilt organometallic complexes, and electroactive and photoactive segments were developed for applications in heterogeneous organocatalysis [ 11 , 12 ], organometallic catalysis [ 13 ], electrocatalysis [ 14 ], and photocatalysis [ 15 ]. Texturally and covalently diverse POPs were prepared for reversible CO 2 capture: non-functional POPs with an ultra-high specific surface area were revealed to be efficient for high-pressure CO 2 capture [ 16 ], while functionalized POPs with a significantly lower specific surface area were suitable for the low-pressure CO 2 trapping [ 17 , 18 ]. Several POPs with polar segments were prepared and tested in reversible water vapour capture from the air [ 19 , 20 ].…”

“…Functionalization of POPs (crucial for most applications) was mostly achieved by the so-called prepolymerization functionalization approach consisting of the polymerization of monomers bearing heteroatom groups or segments in addition to the polymerization-active groups. Bivalent and trivalent heteroatom segments were inbuilt into POPs, often in the form of networks knots created in the course of polymerization (e.g., triazole [ 29 ], imine knots [ 30 ]) or in the form of cyclic building blocks [ 17 , 31 , 32 , 33 , 34 ]. Univalent functional groups were inbuilt into POPs mostly as substituents (pendant groups) of hydrocarbon aromatic building blocks.…”