Tunable porosity of cotton xerogels via ionic liquid-based natural fiber welding

Mesoporous Natural Fiber Welded Cellulose Containing Silver Nanoparticles as a Recyclable Heterogeneous Catalyst

“…Next, the cotton was submerged in 200 mL of water on a benchtop orbital shaker table to extract the IL. The rinse water was replaced after 10, 20, 30, 90, and 180 min and 18.5 h. After this water rinse, the wet cotton was placed in 200 mL of solvent to facilitate a polar‐to‐nonpolar transition: IPA for 24 h, then 2B for 24 h, and lastly CH for 24 h. This rinse procedure is referred to as “the gamut.” [ 21 ] Finally, the cotton was removed from solvent, placed within a glass round bottom flask which was immersed in liquid nitrogen and evacuated to <50 mTorr for 24 h. The dry product was then used as the support for AgNP synthesis.…”

“…IPA was selected (over water) because recent work has determined the fate of the cellulose mesoporous structure can be preserved upon exposure and drying from this solvent. [ 21 ] The IPA‐EN‐Ag solution was added dropwise to NFW cellulose to prepare catalysts with the desired wt% Ag (with respect to the cellulose support). Upon drying in air, the Ag‐laden NFW cellulose composite was subjected to low temperature tube furnace reduction (N 2 at 120 °C for 2 h, then H 2 at 120 °C for 2 h), which the previous study has demonstrated will convert the Ag + to AgNP.…”

“…Natural Fiber Welding and Rinse/Drying Procedure: Welding was performed as per the multisolvent approach introduced in our previous report. [21] In short, ≈0.7 g of untreated cotton yarn was wrapped in a single layer around a Teflon support and submerged in 60 °C EMImAc for 1 h in a nitrogen-filled glove box. Next, the cotton was submerged in 200 mL of water on a benchtop orbital shaker table to extract the IL.…”

“…Recently, our group has shown how the NFW rinsing procedure can be used to tailor the surface area and mesoporosity of the cellulose, a critical consideration for using this material as a catalyst support. [20,21] In short, the NFW process creates a mesoporous structure which will collapse when oven drying from a polar solvent (e.g., water) or be retained when lyophilizing from a nonpolar solvent (e.g., cyclohexane, CH). The resulting mesoporous NFW cellulose (in this case, welded adjacent strands of cotton thread) expresses surface areas ranging from less than 0.01 m 2 g -1 to greater than 200 m 2 g -1 based on final solvent rinse and drying technique.…”

Mesoporous Cellulose-TiO2 Nanoparticle Composite Textile for “Excellent” UV Protection

“…NFW uses an ionic liquid (IL), typically 1-ethyl-3-methylimidazolium acetate (EMImAc), to partially dissolve and subsequently “weld” biopolymer fibers together, enhancing their mechanical properties. − Removing EMImAc with H 2 O or another polar nonsolvent precipitates the biopolymer and generates a welded composite. While drying from polar solvents tends to collapse the biopolymer material into a nonporous state, our lab has recently discovered that rinsing with a polar to nonpolar solvent gradient (i.e., H 2 O → isopropyl alcohol →2-butanone → cyclohexane) produces a porous network throughout the welded biopolymer material and delivers a mesoporous scaffold. , Notably, cellulose thread can be modified by this method to create a composite comprising a high surface area mesoporous scaffold surrounding an unmodified thread core (ca. 200 m 2 g –1 ) with small average pore diameters (ca.…”