Demulsification Performance and Mechanism of Tertiary Amine Polymer-Grafted Magnetic Nanoparticles in Surfactant-Free Oil-in-Water Emulsion

Controlled assembly of superparamagnetic iron oxide nanoparticle into nanoliposome for Pickering emulsion preparation

There has been a surge in effort in the development of various solid nanoparticles as Pickering emulsion stabilizers in the past decades. Regardless, the exploration of stabilizers that simultaneously stabilize and deliver bioactive has been limited. For this, liposomes with amphiphilic nature have been introduced as Pickering emulsion stabilizers but these nano-sized vesicles lack targeting specificity. Therefore in this study, superparamagnetic iron oxide nanoparticles (SPION) encapsulated within liposomes (MLP) were used as Pickering emulsion stabilizers to prepare pH and magnetic-responsive Pickering emulsions. A stable MLP-stabilized Pickering emulsion formulation was established by varying the MLP pH, concentration, and oil loading during the emulsification process. The primary stabilization mechanism of the emulsion under pH variation was identified to be largely associated with the MLP phosphate group deprotonation. When subjected to sequential pH adjustment to imitate the gastrointestinal digestion pH environment, a recovery in Pickering emulsion integrity was observed as the pH changes from acidic to alkaline. By incorporating SPION, the Pickering emulsion can be guided to the targeted site under the influence of a magnetic field without compromising emulsion stability. Overall, the results demonstrated the potential of MLP-stabilized Pickering emulsion as a dual pH- and magnetic-responsive drug delivery carrier with the ability to co-encapsulate hydrophobic and hydrophilic bioactive.

Sequence-Defined Tertiary Amine-Based Oligomer Employing a Scalable, Support-Free, and Protection/Deprotection-Free Iterative Strategy

Sequence-defined oligomers (SDOs) with their unique monomeric sequence and customizable nature are attracting the attention of researchers globally. The structural and functional diversity attainable in SDOs makes this platform promising, albeit with challenges in the synthesis. Herein, we report the design and synthesis of a novel class of SDO by incorporating tertiary amines into the backbone from commercially available inexpensive materials. Tertiary amines were selected due to their various material and biomedical applications. Even though the synthesis and purification of amine compounds are challenging, their various significant applications, such as pharmaceuticals, catalysts, surfactants, corrosion inhibitors, dye intermediates, polymer additives, rubber accelerators, gas treating agents, agriculture, and analytical chemistry, make them fascinating. The synthetic strategy that is designed here is extremely efficient and economical for the scalable synthesis of the SDO and is support-free, protection-deprotection chemistry-free, and catalyst/template-free. Most importantly, no extra design and synthesis of the monomer is required here. The key reactions employed for the SDO synthesis are (i) transformation of the hydroxy group to a halide and (ii) substitution of the halide by the secondary amine units. Including the purifying processes, the multigram synthesis of 4-mer was completed in 12-14 h. The synthetic strategy was established by synthesizing two different sequences of SDOs. The SDOs are characterized by 1H NMR and LC-MS. The tandem MS (MS/MS) experiment was conducted in order to validate the sequences over the SDO chain. Furthermore, the SDO platform was advanced in two ways: (i) by increasing the chain length via attaching a linker, which provides a rapid method for increasing the tertiary amine over the SDO chain, and (ii) postsynthetic modification of SDO with other functional groups, including guanidine for biological importance and a well-known fluorophore dansyl group for material significance.

Preparation of Hydrophobic Octadecylphosphonic Acid-Coated Magnetite Nanoparticles for the Demulsification of n-Hexane-in-Water Nanoemulsions

To design more environmentally friendly, economical, and efficient demulsifiers for oily wastewater treatment, hydrophobic octadecylphosphonic acid (ODPA)-modified Fe3O4 nanoparticles (referred to as Fe3O4@ODPA) were prepared by condensation of hydroxyl groups between ODPA and Fe3O4 nanoparticles using the co-precipitation method. The prepared magnetite nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric/differential thermogravimetric (TG/DTG) analysis. The water contact angles (θW) of Fe3O4@ODPA nanoparticles were more than 120°, indicating hydrophobic nature, and the diameter of the obtained spherical-shaped magnetite nanoparticles was 12-15 nm. The ODPA coating amount (AO) (coating weight per gram Fe3O4) and specific surface area (SO) of Fe3O4@ODPA were 0.124-0.144 g·g-1 and 78.65-91.01 m2·g-1, respectively. To evaluate the demulsification ability, stability, and reusability, the magnetite nanoparticles were used to demulsify an n-hexane-in-water nanoemulsion. The effects of the magnetite nanoparticle dosage (CS), pH value of nanoemulsion, and NaCl or CaCl2 electrolytes on the demulsification efficiency (RO) were investigated. The RO of Fe3O4@ODPA samples was found to be higher than that of bare Fe3O4 samples (S0, ST, and SN) under all CS values. With the increase in CS, the RO of Fe3O4@ODPA samples initially increased and then approached equilibrium value at Cs = 80.0 g·L-1. A maximum RO of ~93% was achieved at CS = 100.0 g·L-1 for the Fe3O4@ODPA sample S2. The pH and two electrolytes had a minor effect on RO. The Fe3O4@ODPA nanoparticles maintained high RO even after being reused for demulsification 11 times. This indicates that the hydrophobic Fe3O4@ODPA samples can be used as an effective magnetite demulsifer for oil-in-water nanoemulsions.

Demulsification of Crude Oil Emulsions Using Versatile and Eco-Friendly Demulsifiers Based on Cellulose Decorated with Imidazolium-Bearing Triazole Moiety

Water in the crude oil forms emulsions that must be broken before refining processes. Here, the novel and versatile derivatives of imidazolium ionic liquids (ILs) containing triazole moiety [SIm-TazCn][Br] were synthesized via click chemistry and then grafted onto the cellulose (CEL) to prepare eco-friendly demulsifiers for breaking water-in-oil (W/O) emulsions. The prepared compounds with two kinds of alkyl chains named CEL[SIm-TazC6][Br] and CEL[SIm-TazC10][Br] were characterized and employed for demulsifying W/O (30:70 and 50:50 vol %) emulsions. Also, the effect of the type and concentration of each demulsifier on the phase separation and dehydration efficiency (DE) were investigated through the bottle test. According to the bottle test results, the CEL[SIm-TazC6][Br] derivative at 4000 ppm showed a good DE of 79% after 5 min, which increased to 82% after 24 h. The interfacial tension (IFT) of derivatives at different concentrations was measured. The minimum IFT value of 16.3 mN/m was obtained for CEL[SIm-TazC6][Br] with a shorter alkyl chain at 4000 ppm after 24 h. The green and efficient CEL-based surfactants significantly demulsified the W/O emulsions because of the collaboration between imidazolium and triazole moieties.