The synthesis of a mesoporous poly(ionic liquid) network via a hard-templating pathway is presented. Structure analysis was carried out using gas adsorption, smallangle X-ray scattering, and electron microscopy. The mesoporous poly(ionic liquid) showed a significantly faster CO 2 adsorption than its nonporous counterpart. We found the adsorption is accompanied by strong interactions, which are also reflected in a high CO 2 over N 2 selectivity. P oly(ionic liquid)s (PILs) stand for a subclass of polyelectrolytes, the repeating unit of which has ionic liquid (IL) character. The research scope in PILs recently has significantly expanded. 1 It is generally accepted that the incorporation of IL moieties into the polymer chain combines some of the unique characters of ILs with the common features of polymers. The synergistic effect produces immediately a variety of new (multi)functional materials, 1−4 among which the controlled capture or separation of carbon dioxide (CO 2 ) is of special interest. Several groups have reported that bulk PILs exhibited quick and enhanced CO 2 uptake compared to their low molecular IL counterparts. These research efforts were devoted mainly to PILs with novel chemical structure that showed a higher affinity to CO 2 .An orthogonal pathway is to provide PILs with a nanostructure with enlarged surface area to amplify the gas uptake. PIL nanoparticles have been reported recently, yet as colloids in aqueous solution. 5 There are a few reports on macroporous PILs, 5b,6 with surface areas of up to 37 m 2 ·g −1 . 6a A mesoporous material (with pore sizes between 2 and 50 nm) would indeed provide on the one hand sufficiently high surface area and acceptable mass transfer at the same time. This explains the huge interest of the scientific community in mesoporous materials. 7 Given the huge potential of PILs in gas sorption and separation but also heterogeneous catalysis, mesoporous PILs (mpPILs) are a next step to improve their functional properties. Herein we describe the synthesis of mpPILs via a hardtemplating pathway, which feature well-defined mesopore sizes and pore shapes. The interactions and adsorption kinetics of the mpPILs with CO 2 are studied in detail.The synthesis is based on hard-templating of silica nanoparticles. 8 Silica nanoparticles (LUDOX TM-50, nominal diameter: 25 nm) were slowly dried, forming thereby a mesoporous, opal-like silica. Backfilling of the interstitial voids with the monomer/initiator mixture and subsequent polymerization results in an organic−inorganic hybrid. Etching of the inorganic component finally liberates the mesoporous polymer (Scheme 1b). We learned from previous works that a high degree of cross-linking is necessary to stabilize the polymer structure against collapse after silica template removal. 9 A cross-linkable monomer was prepared by reaction of 1-vinylimidazole with 4-vinyl benzyl chloride to yield 3-(4-vinylbenzyl)-1-vinylimidazolium chloride (Scheme 1a). The [Cl − ] anion was exchanged to bis(trifluoro methylsulfonyl)-imide [Tf 2 N − ] t...
Multicomponent flame retardant systems containing aluminum diethylphosphinate in thermoplastic styrene-ethylene-butylene-styrene elastomers are investigated (oxygen index, UL 94, cone calorimeter, and mechanical testing). Solid-state nuclear magnetic resonance, scanning electron microscopy, and elemental analysis illuminate the interactions in the condensed phase. Thermoplastic styrene-ethylene-butylene-styrene elastomers are a challenge for flame retardancy (peak heat release rate at 50 kW m 22. 2000 kW m 22 , oxygen index = 17.2 vol%, no UL-94 horizontal burn rating) since it burns without residue and with a very high effective heat of combustion. Adding aluminum diethylphosphinate results in efficient flame inhibition and improves the reaction to small flame, but it is less effective in the cone calorimeter. Its efficacy levels off for amounts .;25 wt%. As the most promising synergistic system, aluminum diethylphosphinate/ melamine polyphosphate was identified, combining the main gas action of aluminum diethylphosphinate with condensed phase mechanisms. The protection layer was further improved with several adjuvants. Keeping the overall flame retardant content at 30 wt%, aluminum diethylphosphinate/melamine polyphosphate/titanium dioxide and aluminum diethylphosphinate/ melamine polyphosphate/boehmite were the best approaches. An oxygen index of up to 27 vol%
Developing flame retarded thermoplastic elastomers (TPE-S) based on styrene–ethylene–butylene–styrene, polypropylene, and mineral oil is a challenging task because of their very high fire loads and flammability. A promising approach is the synergistic combination of expandable graphite (EG) and ammonium polyphosphate (APP). Cone calorimetry, oxygen index, and UL 94 classification were applied. The optimal EG:APP ratio is 3:1, due to the most effective fire residue morphology. Exchanging APP with melamine-coated APPm yielded crucial improvement in fire properties, whereas replacing EG/APP with melamine polyphosphate did not. Adjuvants, such as aluminum diethyl phosphinate (AlPi), zinc borate, melamine cyanurate, titanium dioxide, dipentaerylthritol, diphenyl-2-ethyl phosphate, boehmite, SiO2, chalk, and talcum, were tested. All flame retardants reinforced the TPE-S. The combination with AlPi is proposed, because with 30 wt % flame retardants a maximum averaged rate of heat emission below 200 kW m–2 and a V-0 rating was achieved. Multicomponent EG/APP/adjuvants systems are proposed as a suitable route to achieve efficient halogen-free flame retarded TPE-S.
The preparation of ultraporous polymer resins using a straightforward hard-templating synthesis is presented. Self-assembly of silica nanospheres into densely packed glasses allows an easy preparation of templates. Polydivinylbenzene resins with surface areas of up to 1000 m(2) g(-1) are synthesized as a model system and porosity analysis reveals bimodal porosity (spherical mesopores and micropores within the pore walls). The prepared systems can be further functionalized without loss of porosity as demonstrated by sulfonation. Because of their large pore sizes (13-28 nm), they are efficient adsorbents also for large molecules. Finally, the systems can also be used as model systems for the study of the pore drying and collapse process, which is of crucial importance for any application of mesoporous polymers.
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