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 C-13 cross-polarization magic angle spinning NMR, thermogravimetric analysis, and N(2) adsorption/desorption and their efficiency in CO2 and H2O capturing is discussed in relation to the content and type of incorporated pyridine segments.