Microemulsions are thermodynamically stable, fluid, optically clear dispersions of two immiscible liquids. Recent interest in microemulsion systems has resulted from their utility in a broad range of applications including enhanced oil recovery, consumer and pharmaceutical formulations, nanoparticle synthesis, and chemical reaction media. However, the high levels typically required to ensure complete microemulsification and formulation stability often result in unacceptably high residue, contaminant levels, and formulation cost. One way to reduce surfactant requirements in microemulsion systems is through the use of efficient surfactants and interfacially active cosurfactants. We have explored and developed microemulsion systems based on efficient anionic surfactants and glycol ether cosurfactants that are stable to temperature and compositional changes and yet employ low levels of non‐volatile surfactants. These microemulsion systems are finding utility in a range of applications, including consumer and industrial cleaning formulations, chemical reaction media, polymerization, and active ingredient delivery.

No abstract

Surface-active asphaltene molecules are naturally found in crude oil, causing serious problems in the petroleum industry by stabilizing emulsion drops, thus hindering the separation of water and oil. Asphaltenes can adsorb at water-oil interfaces to form viscoelastic interfacial films that retard or prevent coalescence. Here, we measure the evolving interfacial shear rheology of water-oil interfaces as asphaltenes adsorb. Generally, interfaces stiffen with time, and the response crosses over from viscous-dominated to elastic-dominated. However, significant variations in the stiffness evolution are observed in putatively identical experiments. Direct visualization of the interfacial strain field reveals significant heterogeneities within each evolving film, which appear to be an inherent feature of the asphaltene interfaces. Our results reveal the adsorption process and aged interfacial structure to be more complex than that previously described. The complexities likely impact the coalescence of asphaltene-stabilized droplets, and suggest new challenges in destabilizing crude oil emulsions.

No abstract

A disodium 1,2-ethanediol bis(hydrogen sulfate) salt, [NaO3SOCH2CH2OSO3Na], has been synthesized and anchored onto zirconium hydroxide to produce a high concentration of solid dual acid sites. The reaction of HCON(CH3)2·SO3, (CH2OH)2, and NaOH produced a stable [NaO3SOCH2CH2OSO3Na] precursor in 40% yield. The [NaO3SOCH2CH2OSO3Na] salt was exchanged with NH4 + using an NH4−R resin followed by impregnation of a zirconium hydroxide slurry, yielding [−O3SOCH2CH2OSO3−]2- anchored on Zr(OH)4. The characterization of the samples included high-resolution X-ray photoelectron, near-infrared diffuse reflectance, 1H NMR, and 13C magic angle spinning NMR spectroscopies. The results provided evidence of a μ2-CH2CH2− ligand bridged between two −OSO3− groups in the precursor and the anchored precursor. The ethyl bridge was removed upon calcination at 500 °C to yield surface-grafted acid groups on zirconia. This material had a surface area of 97 m2 g-1 and an acid-exchange capacity of 0.70 mequiv of H+/g, corresponding to 7.2 μmol acid sites/m2, which was about 50% higher than that of sulfated zirconia prepared by standard methods of impregnation by sulfuric acid or ammonium sulfate.

Efficient encapsulation of tetraethylenepentamine (TEPA), as an example aliphatic amine, was achieved by an emulsion-templated, in situ polymerization. Hydrophobically modified clay nanoplatelets were employed as emulsifiers to obtain water-in-oil (W/O) dispersions followed by interfacial polymerization between a portion of the TEPA cargo and polymethylene polyphenylene isocyanate (PMPPI). The resultant capsules exhibit spherical shape, desirable thermal stability, modest barrier properties, and shear-induced release in an epoxide monomer mixture. Most importantly, a significant gain in capsule barrier properties was realized by introducing poly(allyl amine) (pAAm) as an interface-selective reactive additive in the Pickering emulsions. In addition to the fundamental interest of pAAm localization and interface-selective reactivity, this microencapsulation system for aliphatic amines has technological potential in coating, self-healing, and drug-delivery applications.

A novel disodium 1,2-ethanediol bis(hydrogen sulfate) salt precursor-based solid acid catalyst is demonstrated to have significantly enhanced activity and high selectivity in producing methyl isobutyl ether (MIBE) or isobutene from a methanol-isobutanol mixture. This journal is

We report the synthesis and characterization of catechol-functionalized film-forming latexes that display excellent adhesion to low-surface-energy polyolefin-based substrates. The aromatic 1,2-diol functional group in catechol derivatives is believed to be responsible for enhancing the adhesion of a variety of polymers to a range of substrates. Here, we describe a postpolymerization modification approach to the design of emulsion polymers with catechol-functionalized side chains. A series of analogous small-molecule reactions, together with latex characterization by infrared (IR) spectroscopy and liquid chromatography (LC) methods, provides evidence for polymer functionalization. Films prepared from catechol-containing latexes displayed remarkable adhesion to challenging, commercially-available thermoplastic polyolefin (TPO) (as determined by a standard ASTM cross-hatch method). We provide evidence that covalent bonding and the unique catechol structure are required to promote adhesion. The catechol-functionalized emulsion polymers reported here represent a new class of functional latex, and this postpolymerization modification approach will present further opportunities to improve, modulate, and control the adhesion of water-borne coatings to a variety of polyolefin-based substrates.