RESUMO
Two series of hyper-cross-linked microporous polyacetylene networks containing either -[CH=C(CH=O)]- or -[CH=C(CH2OH)]- monomeric units are reported. Networks are prepared by chain-growth copolymerization of acetal-protected propargyl aldehyde and acetal-protected propargyl alcohol with a 1,3,5-triethynylbenzene cross-linker followed by hydrolytic deprotection/detemplating. Deprotection not only liberates reactive CH=O and CH2OH groups in the networks but also modifies the texture of the networks towards higher microporosity and higher specific surface area. The final networks with CH=O and CH2OH groups attached directly to the polyene main chains of the networks have a specific surface area from 400 to 800 m2/g and contain functional groups in a high amount, up to 9.6 mmol/g. The CH=O and CH2OH groups in the networks serve as active centres for the reversible capture of CO2 and water vapour. The water vapour capture capacities of the networks (up to 445 mg/g at 297 K) are among the highest values reported for porous polymers, making these materials promising for cyclic water harvesting from the air. Covalent modification of the networks with (R)-(+)-3-aminopyrrolidine and (S)-(+)-2-methylbutyric acid enables the preparation of porous chiral networks and shows networks with CH=O and CH2OH groups as reactive supports suitable for the anchoring of various functional molecules.
RESUMO
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 13 C cross-polarization magic angle spinning NMR, thermogravimetric analysis, and N2 adsorption/desorption and their efficiency in CO2 and H2 O capturing is discussed in relation to the content and type of incorporated pyridine segments.
