Bicompartmental Phase Transfer Vehicles Based on Colloidal Dimers

Abstract

Colloidal particles have been used extensively for stabilizing oil-water interfaces in petroleum, food, and cosmetics industries. They have also demonstrated promising potential in the encapsulation and delivery of drugs. Our work is motivated by challenging applications that require protecting and transporting active agents across the water-oil interfaces, such as delivering catalysts to underground oil phase through water flooding for in situ cracking of crude oil. In this Research Article, we successfully design, synthesize, and test a unique type of bicompartmental targeting vehicle that encapsulates catalytic molecules, finds and accumulates at oil-water interface, releases the catalysts toward the oil phase, and performs hydrogenation reaction of unsaturated oil. This vehicle is based on colloidal dimers that possess structural anisotropy between two compartments. We encapsulate active species, such as fluorescent dye and catalytic molecules in one lobe which consists of un-cross-linked polymers, while the other polymeric lobe is highly cross-linked. Although dimers are dispersible in water initially, the un-cross-linked lobe swells significantly upon contact with a trace amount of oil in aqueous phase. The dimers then become amphiphilic, migrate toward, and accumulate at the oil-water interface. As the un-cross-linked lobe swells and eventually dissolves in oil, the encapsulated catalysts are fully released. We also show that hydrogenation of unsaturated oil can be performed subsequently with high conversion efficiency. By further creating the interfacial anisotropy on the dimers, we can reduce the catalyst release time from hundred hours to 30 min. Our work demonstrates a new concept in making colloidal emulsifiers and phase-transfer vehicles that are important for encapsulation and sequential release of small molecules across two different phases.

Fabrication of Ternary Hybrid Colloids via In‐Situ Polymerization at the Interface of Oil/Water Emulsion

“…3-methacryloxypropyltrimethoxysilane (MPS) was purchased from Alfa Aesar. 2-[methoxy (polyethyleneoxy) [6][7][8][9] propyl)] trimethoxysilane (PEO-TMS) and coumarine-6 were purchased from J&K. TEPA, KPS, sodium dodecyl benzenesulfonate (SDS), n-pentane, n-hexane, and n-heptane were purchased from Sinopharm Chemical Reagent Beijing Co., Ltd. N,N-dimethylformamide (DMF), ammonium fluoride (NH 4 F) and ethanol was purchased from Beijing Chemical Works. All the reagents were used as received unless otherwise stated.…”

“…[1][2][3][4] Ternary hybrid colloids (THCs), [5] a class of asymmetric colloids, consist of three different compositions with distinct compartments on the same particle. Because of their special morphology and composition, these asymmetric colloids have shown great promise in drug delivery, [6][7][8] catalyst, [9][10][11] self-propelled nanomotors, [12][13][14] surfactants, [15,16] and forth. [17,18] Progress in nanotechnology has made it possible to construct numerous asymmetric colloids with different functionalities.…”

Control of cross-linking and reactions in one-step dispersion polymerization toward particles with combined anisotropies

“…Sodium pstyrene sulfonate (NaSS, 99.9%), methacrylic acid (MAA, 99%), propargyl methacrylate (PMA, 98%), and 1, 7-Octadiyne (1, 7-OTD, 98%) were purchased from Alfa Aesar and used without further purification. 4 …”

A Surfactant-Free and Shape-Controlled Synthesis of Nonspherical Janus Particles with Thermally Tunable Amphiphilicity

“…Janus particles are known to locate at liquid–liquid interfaces to stabilize two immiscible liquids, producing particle‐assisted emulsions (Pickering emulsion) . At the interfaces, they sometimes show catalytic activity for chemical reactions or phase transfer processes in complex fluids . Janus particles are also being considered for use in biomedicine and optoelectronics, as well as for fabricating various assembly structures and antireflectivity surfaces …”

“…Various strategies have been suggested to form Janus spherical particles; e.g., partial exposure of spherical particles to hydrophobic components, introduction of electrodynamic cojetting methods, and phase separation or selective coating of a block of polymers during polymerization . For nonspherical particles, the Janus characteristic was mostly accomplished after the synthesis of dumbbell‐shaped particles by conducting additional surface modification of specific blocks . In the meantime, the use of core–shell particles was found to be useful to directly impart Janus characteristics to nonspherical particles .…”