Hydrogen Storage in Microporous Hypercrosslinked Organic Polymer Networks

Abstract

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.

Porous organic molecular solids by dynamic covalent scrambling

“…A periodic simulation cell was built containing 32 cage molecules chosen to represent the numerical distribution of species observed by HPLC. The simulated bulk density for the model was 0.766 g cm − 3 , which is close to that measured for the sample experimentally (0.716 g cm − 3 ) using a combination of gas sorption and helium pyknometry 6 . Interconnected pore channels can be identified in the model, which permeate the simulation cell, running both through and between the cages.…”

“…M ost materials with molecular-scale pores are extended networks [1][2][3][4][5][6][7][8] , but not solution-processable molecules of the kind commonly prepared by organic chemists. Indeed, the vast majority of organic molecules pack efficiently in the solid state to form structures with minimal void volume.…”

“…Permanent, interconnected porosity in discrete organic molecules with low molar mass is rarer 11 and is typically confined to certain ordered molecular crystals [12][13][14][15][16][17][18][19][20][21][22][23][24] . Examples include modified calixarenes [12][13][14] , 3,3′,4,4′-tetra(trimethylsily lethynyl)biphenyl 15 , tris-o-phenylenedioxycyclotriphosphazene 16 , 4-hydroxyphenyl-2,3-4-trimethylchroman 17 , cucurbit [6]uril 18 , some dipeptides 19 , diyne macrocycles 20 and imine-linked porous organic cages 21,22 . Two main strategies have been used to prepare porous organic molecular solids.…”

“…More commonly, molecular crystals that contain cavities or channels, such as clathrates and solvates, do not retain their incipient porosity on guest removal and collapse to form a denser phase 11 . This is a key distinction between porous molecular crystals and porous crystalline networks [1][2][3][4][5][6][7][8] , where structural collapse may be prevented by extended directional covalent or coordination bonding.…”

Unprecedented high-temperature CO2 selectivity in N2-phobic nanoporous covalent organic polymers

“…These mostly organic polymers can easily be designed and constructed via facile synthetic protocols. To date, several crystalline and amorphous nanoporous organic materials with tunable functionality have been developed-namely, COF 14 , PIM 15 , HCP and CMP 16,17 , CTF 18 , PAF 19 , PPN 20 , POF 21 , BILP 22 , EOF 23 , PECONF 24 and COP 25 .…”