Preparation and retention mechanism exploration of mesostructured cellular foam silica as stationary phase for high performance liquid chromatography

ZnO/PDA/Mesoporous Cellular Foam Functionalized Thin-Film Nanocomposite Membrane towards Enhanced Nanofiltration Performance

Thin-film nanocomposite (TFN) membranes are the third-generation membranes being explored for nanofiltration applications. Incorporating nanofillers in the dense selective polyamide (PA) layer improves the permeability-selectivity trade-off. The mesoporous cellular foam composite Zn-PDA-MCF-5 was used as a hydrophilic filler in this study to prepare TFN membranes. Incorporating the nanomaterial onto the TFN-2 membrane resulted in a decrease in the water contact angle and suppression of the membrane surface roughness. The pure water permeability of 6.40 LMH bar^-1 at the optimal loading ratio of 0.25 wt.% obtained was higher than the TFN-0 (4.20 LMH bar^-1). The optimal TFN-2 demonstrated a high rejection of small-sized organics (>95% rejection for 2,4-dichlorophenol over five cycles) and salts-Na₂SO₄ (≈95%) > MgCl₂ (≈88%) > NaCl (86%) through size sieving and Donnan exclusion mechanisms. Furthermore, the flux recovery ratio for TFN-2 increased from 78.9 to 94.2% when challenged with a model protein foulant (bovine serum albumin), indicating improved anti-fouling abilities. Overall, these findings provided a concrete step forward in fabricating TFN membranes that are highly suitable for wastewater treatment and desalination applications.

Composite Membranes Based on Functionalized Mesostructured Cellular Foam Particles and Sulfonated Poly(Ether Ether Sulfone) with Potential Application in Fuel Cells

Composite polymeric membranes were designed based on sulfonated poly(ether ether sulfone) (sPEES) and mesostructured cellular foam (MCF) silica nanoparticles functionalized with organic compounds. Parameters such as molecular weight (MW) of the polymer, nature of the functional group of the MCF silica, and percentage of silica charge were evaluated on the final properties of the membranes. Composite membrane characterization was carried out on their water retention capacity (high MW polymer between 20-46% and for the low MW between 20-60%), ion exchange capacity (IEC) (high MW polymer between 0.02 mmol/g-0.07 mmol/g and low MW between 0.03-0.09 mmol/g) and proton conductivity (high MW polymer molecular between 15-70 mS/cm and low MW between 0.1-150 mS/cm). Finally, the membrane prepared with the low molecular weight polymer and 3% wt. of functionalized silica with sulfonic groups exhibited results similar to Nafion® 117.

Preparation and application of PGMA-DVB microspheres via surface-modification with quaternary and phenylboronic acid moiety

Porous cross-linked poly (glycidyl methacrylate-divinylbenzene) (PGMA-DVB) particles (7.42 ± 0.24 μm in diameter) were prepared by an improved two-step seed swelling polymerization method. The PGMA-DVB particles were further modified with poly (allylamine hydrochloride) (PAH) and 4-(bromomethyl) phenylboronic acid (BPA), which were used as high performance liquid chromatography (HPLC) filler for nucleotides separation. The liquid chromatographic column packing materials successfully achieved complete separation of nucleotides mixture or deoxynucleotides mixture based on non-polar adsorption, hydrogen bonding interaction and electrostatic adsorption. Reckoning on the chemical structure of BPA, nucleotides and deoxynucleotides with same base group were also separated. The column packing materials were durable after over 100 time running or 7 days. It presents a kind of new notion for the separation of nucleotides by HPLC.

Recent advances in mixed-mode chromatographic stationary phases

Mixed-mode phases have become very popular in the last decade, and the number of new mixed/multi-mode sorbents is growing fast. Unlike single-mode stationary phases, perfectly suited for the separation of the analytes possessing similar physicochemical properties, for instance reversed-phase chromatography for hydrophobic solutes, mixed-mode sorbents providing multimodal interactions can render better separation selectivity for complex mixtures of solutes differing significantly in their physicochemical characteristics. The most frequent modern mixed-mode stationary phases are di/tri-mode sorbents embracing the following interactions, hydrophobic, electrostatic (coulombic), and hydrophilic. According to their structures, it is possible to distinguish silica-based, polymer-based, hybrid, and monolithic mixed-mode stationary phases. Herewith, newly synthesized mixed-mode sorbents developed within the last two and half years are categorized, discussed, and summarized. The main attention is devoted to the description of the synthetic routes and characterization methods applied for the new stationary phases.

Preparation and evaluation of surface-grafted block copolymers and random copolymers via surface-initiated atom transfer radical polymerization for hydrophilic/ion-exchange stationary phases

Mixed-mode chromatographic (MMC) stationary phases must be functionalized with at least two functional groups to yield multiple interactions.