Rigid wiry nets: Conjugated microporous polymer networks are formed by Sonogashira–Hagihara coupling. Although these materials are amorphous, the micropore size and surface area can be controlled by varying the length of the phenyleneethynylene struts (see picture; the network is shown in blue, and one 1,3,5‐substituted benzene node and three connected struts are highlighted with C gray and H white).
A series of rigid microporous poly(aryleneethynylene) (PAE) networks was synthesized by Sonogashira-Hagihara coupling chemistry. PAEs with apparent Brunauer-Emmet-Teller surface areas of more than 1000 m(2)/g were produced. The materials were found to have very good chemical and thermal stability and retention of microporosity under a variety of conditions. It was shown that physical properties such as micropore size, surface area, and hydrogen uptake could be controlled in a "quantized" fashion by varying the monomer strut length, as for metal-organic and covalent organic frameworks, even though the networks were amorphous in nature. For the first time, it was demonstrated that these properties can also be fine-tuned in a continuous manner via statistical copolymerization of monomer struts with differing lengths. This provides an unprecedented degree of direct synthetic control over micropore properties in an organic network.
Covalent triazine frameworks (CTFs) are normally synthesized by ionothermal methods.T he harsh synthetic conditions and associated limited structural diversity do not benefit for further development and practical large-scale synthesis of CTFs.Herein we report anew strategy to construct CTFs (CTF-HUSTs) via apolycondensation approach,which allows the synthesis of CTFs under mild conditions from aw ide arrayo fb uilding blocks.I nterestingly,t hese CTFs displayalayered structure.T he CTFs synthesized were also readily scaled up to gram quantities.T he CTFs are potential candidates for separations,p hotocatalysis and for energy storage applications.I np articular,C TF-HUSTs are found to be promising photocatalysts for sacrificial photocatalytic hydrogen evolution with am aximum rate of 2647 mmol h À1 g À1 under visible light. We also applied ap yro-lyzed form of CTF-HUST-4 as an anode material in asodium-ion battery achieving an excellent discharge capacity of 467 mAh g À1. Covalent organic frameworks (COFs) are an emerging class of porous materials,characterized by their ordered structures, high surface areas,and structural diversity. [1] They have shown promise in applications such as gas adsorption, [2] catalysis, [3] and optoelectronics. [4] Av ariety of methods have been reported to prepare COFs,s uch as polycondensation, [1a, 4a] cyclization reactions, [5] or surface mediated methods. [1b, 6] Covalent triazine frameworks (CTFs) are related to COFs and are typically constructed through cyclization reaction of nitrile aromatic building blocks;t hey feature high physico-chemical stability and high nitrogen content. [5, 7] Because of these characteristics,CTFs have found diverse applications in gas adsorption and storage, [5a, 7a,b] catalysis, [7c-e] and energy storage. [7f,g] There are still, however, al imited number of approaches for the synthesis of CTFs. [5a, 7a] Themost common approach is ionothermal synthesis at high temperatures (! 400 8 8C), which also requires alarge amount of ZnCl 2 to serve as both catalyst and reaction medium. [5a] This method can lead to CTFs with ad egree of crystalline order,b ut the high reaction temperatures cause the partial carbonization of the structure and the materials are obtained in the form of black powders.H ence,C TFs prepared by this method lack an electronic band gap and may be unsuitable for photophysical applications.F urthermore,t hese reaction temperatures consume alarge amount of energy and preclude all but the most stable building blocks,thus limiting the scope for scale up and synthetic diversity.I ti s, therefore,i mperative to find new methods for the synthesis of CTFs under milder conditions. Previous research has shown that CTFs could be synthesized at room temperature,a nd catalyzed by strong and corrosive acid such as trifluoromethylsufonic acid. [7a,b] This avoids carbonization, but the method is obviously not suitable to acid-sensitive building blocks,and also the resulting materials did not have layered structures. Here,wedevelop anew strategy involvi...
A series of hypercrosslinked polymer networks has been synthesized by the self-condensation of bischloromethyl monomers such as dichloroxylene (DCX), 4,4′-bis(chloromethyl)-1,1′-biphenyl (BCMBP), and 9,10-bis(chloromethyl)anthracene (BCMA). These materials are predominantly microporous and exhibit Brunauer-Emmett-Teller (BET) surface areas of up to 1904 m 2 /g as measured by N 2 adsorption at 77.3 K (Langmuir surface area ) 2992 m 2 /g). Networks based on BCMBP exhibit a gravimetric storage capacity of 3.68 wt % at 15 bar and 77.3 K, the highest yet reported for an organic polymer. The micro-and mesostructure of the networks is explained by a combination of solid-state NMR, gas sorption measurements, pycnometry, and molecular simulations. The isosteric heat of sorption for H 2 on these materials is found to be in the range 6-7.5 kJ/mol. A molecular model is presented for a p-DCX network that simulates well certain key physical properties such as pore volume, pore width, absolute density, and bulk density. This model also predicts the isotherm shape and isosteric heat for H 2 sorption at 77.3 and 87.2 K but overestimates the absolute degree of H 2 uptake, most likely because of a degree of occluded, inaccessible porosity in the real physical samples.
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