The Triazine‐based Porous Organic Polymer: Novel Synthetic Strategy for High Specific Surface Area

Abstract

Low-density porous materials conjugated with organic compounds have garnered considerable scientific attention, because the diverse pore structures and sizes can be easily tuned by simply changing constructional units, even without varying the synthetic route.1 Among the class of low-density porous materials, porous organic polymers (POPs) are the most cost-effective materials, with high-accessible surface area. Based on the nature of the polymerization, strong covalent bonds with various functionalities such as amide, ester, and imine can be easily formed according to the choice of monomers. Moreover, the polymer can also be hyperbranched depending on the monomer structures together with cross-linking between hyperbranched chains. Therefore, high specific surface area can be achieved, although this strategy generally results in amorphous materials. Recently, several nitrogen-rich POPs based on triazine moiety have been synthesized for CO 2 capture, catalysts, and the precursors of N-doped graphenes.3,4 As nitrogen atoms in adsorbents are strong Lewis base sites, these can provide favorable binding sites for CO 2 and metals which can be utilized for catalysts. However, the high specific surface area with triazine moieties has been achieved by trimerization reaction of dicyano-aromatic compounds under harsh conditions requiring high temperature or super acid solution. In this contribution, to induce the hyperbranched polyimide network, the central monomer of tetra(4,6-diamino-s-triazine-2-yl)tetraphenylmethane (M1) described in Scheme 1 was synthesized by following a method previously reported in the literature. 6 To synthesize the POP, M1 and naphthalenetetracarboxylic dianhydride (NTCDA) were dissolved with a molar ratio of 1:4 in dimethyl sulfoxide (DMSO).7 Then, the solution was refluxed for 72 h (Scheme 1). After completion of the reaction, the resulting solution was suspended in water and filtrated. Lastly, the product was purified with a successive Soxhlet extraction with water, methanol, and ethanol. Finally, half of the resulting POP was dried under vacuum at 100 C, and the other half was soaked in ethanol for 72 h with ethanol replacement every 24 h prior to a supercritical CO 2 drying method. , and 65 ppm. The first peak especially has a shoulder at ca. 170 ppm, and peaks in this region presumably arise from the carbon atoms in triazine rings and the carbon atoms in the carbonyl group of imide. In addition, the resonance at approximately 120~155 ppm can be assigned to the aromatic carbons in benzene moieties. The last peak can be associated to the central C atoms of the triphenylmethane moieties in the resulting polyimide network. Therefore, based on all the above characteristic peaks, it is clearly demonstrated that the desired POP as a new copolymer network was successfully synthesized. The pore structure of the POP was probed by N 2 adsorption/desorption isotherm analyses at 77 K using two aforementioned activation methods (Figure 2(a) and (b)). The isotherms for both polyamide networks represent a ...

Redox-driven strong interfacial interactions between MnO2 and covalent organic nanosheets for efficient oxygen reduction electrocatalysis

“…The morphology of CON-32 was consistent with the literature, wherein micron-sized globular particles were observed to be present on plate-like sheets. 20,29,30 Furthermore, the globular particles appeared to be agglomerates of sheet-like particles, as shown in the inset of Fig. 2a.…”

“…More specically, isotherms of the two pristine materials showed the typical features exhibited by nonporous materials, as dened by the IUPAC classication. 30,31 Although CON-32 contains mesopores on its individual sheets (see Scheme 1 and Fig. S5 of the ESI †), different framework linkages led to agglomeration and crumpling of the sheets, which led to blockage of the micropores and mesopores.…”

Advances in the Synthesis of Covalent Triazine Frameworks

“…synthesized hyperbranched polyimide networks by condensation of tetra(4,6-diamino- s -triazine-2-yl)tetraphenyl methane (M1) with 1,4,5,8-naphthalenetetracarboxylic anhydride (NTCDA) in DMSO solution. 101 The diaminotriazine fraction in M1 can provide an effective branched site, giving the synthesized CTFs a specific surface area of 1150 m 2 g –1 . It is worth noting that the void structure of the polyimide porous organic polymers synthesized by Park et al can be modified by supercritical CO 2 surface activation to tune the pore structure.…”

Redox-active polyimides for energy conversion and storage: from synthesis to application

“…59,60 Combination of these A 2 and B 3 -type monomers constructs cross-linked porous structures that enhance the accessibility of reactants such as Li + or redox substances. [61][62][63][64][65] Although microporous PI extended the utility range of the latter as a membrane for gas and energy storage purposes, the limitation still exists due to its low specific surface area and non-uniform pore size.…”