The transfer of electronic excitation energy from rhodamine 6G as an energy donor to thionine as an acceptor has been studied in anionic microemulsion by the method of fluorescence quenching and sensitization. The concentrations of both donor and acceptor used in this study are quite high, in the range of 10−3 M. Both radiative and nonradiative processes have been taken into account, with the major contribution coming from the nonradiative path. An energy transfer efficiency up to 50% has been observed, and the rate constant of the nonradiative energy transfer from rhodamine 6G to monomeric thionine is 5 × 1011 M−1 s−1. This indicates that the nonradiative energy transfer belongs to the long-range Forster-type of dipole–dipole interaction. The results also show why the efficiency of a photogalvanic cell based on the thionine–iron system in anionic microemulsion is enhanced by the incorporation of an auxiliary absorber.

Cadmium sulfide nanoparticle/polymer composites have been produced using a one-system reverse micellar synthesis. A monomer, methyl methacrylate (MMA), was used as the oil and polymerized following formation of 2-3 nm CdS particles in the fluid medium. When Aerosol OT (ACT was employed as the surfactant, opaque solids containing 20-80 nm aggregates of the CdS nanoparticles were obtained. The aggregates were fairly uniform in size, their diameter depending on the AOT concentration. With a 1:1 weight ratio of MMA and a polyethylene diacrylate, aggregation was eliminated but the solid remained opaque. Replacing the AOT by the polymerizable surfactant didecyldimethylammonium methacrylate with MMA as the oil led to the formation of a transparent solid matrix containing nonaggregated CdS particles.

A water-in-toluene microemulsion stabilized by the polymerizable surfactant didecyldimethylammonium methacrylate has been used to form polyelectrolyte particles. The microemulsion was photopolymerized using AIBN as the initiator, resulting in aggregates having hydrodynamic diameters of ∼11 nm, starting with 5–6 nm initial nanodroplets with and without added sodium methacrylate (NaMA). The dried latexes have a diameter of 6 nm up to a [NaMA]/[surfactant] mole ratio ( R ) of 0.5, but 12 nm for R =1.0. For R =0–0.5, the maximum degree of polymerization was 50%, but it was 83% for R =1.0. The polydispersity decreases with increasing R , while the film-forming tendency of the latexes increases.

The polishing of copper and examination of the polished surfaces were carried out with surfactant based alumina slurries to yield interesting results. Contrary to our expectation and previously reported research, some of the surfactant based alumina slurries resulted in higher copper polish rates when compared to the control. Of the nonionic surfactants, BrijR 35 was overall the most effective in both acidic and basic media. Ionics were effective at the pH for the appropriate charge type. For the range of surfactants studied, polish rates correlated with the HLB of the nonionic surfactants. The Hydrophile-Lipophile Balance (HLB) is related to the solubility of the surfactant, with higher number corresponding to increased water dispersibility. The surfactant BrijR 35, with the nonionic composition polyoxyethylene(23) lauryl ether, resulted in a dramatic improvement in the average surface uniformity when compared with the control at pH 2, and Sodium Dodecyl Sulfate produced even greater uniformity. Additionally, the effect of BrijR 35 surfactant was maintained with change in abrasive size, pad and polishing tool. In order to insure that surfactants are compatible with the chemical reagents contained in the commercial slurries, two chemistries (ferric nitrate and hydrogen peroxide) were employed to test the efficiency of the selected surfactants in their presence. The results showed that the effect of surfactant on stability and removal rate is not influenced by the presence of the chemicals. Preliminary results indicate that surfactants can have a beneficial effect on both defects and post polish clean.

The influence of cationic polyelectrolytes, poly[(diallyldimethylammonium chloride)-co-(N-methyl-N-vinylacetamide)] (poly(DADMAC-co-NMVA)) of different charge density in contract to that of a noncharged polymer, poly(N-methyl-N-vinylacetamide) (polyNMVA), on the lamellar liquid crystalline system sodium dodecyl sulfate (SDS)/decanol/water was investigated by means of microscopy observation between crossed polarizers, by small angle X-ray diffraction, and by theology. The lamellar liquid crystal remained stable in all investigated formulations. The results depended on the charge density as well as the concentration of the incorporated polymer. For the polymer with the highest charge two lamellar structures existed concurrently. In excess of a certain concentration the highest charged polymer adsorbed flat onto the SDS-decanol bilayer as shown by its changed interlayer spacing, whereas at lower concentration the polymer did not have a discernible effect on the X-ray diffraction pattern. The results obtained for mixtures of the lowest charged polymer are in accordance with a loop adsorption of the polymer onto the SDS-decanol bilayer. Incorporation of the noncharged polymer did not lead to such adsorption structures and a conclusion of the importance of electrostatic interactions depending on the charge density of the polymer is reasonable. The results obtained by SAXS measurements were supported by the results of rheological measurements.

Copper dissolution in ammonia-containing media during chemical-mechanical polishing (CMP) was investigated. Both a stationary and a rotating disk electrode (RDE) were used for electrochemical characterization. Ammonia can etch copper in the presence of oxidizers by dissolving the oxide film on the copper surface and the dissolution rate varied from about 8 to 30 nm/min, depending on the hydrodynamic conditions. The copper dissolution rate in NH4NO3 or (NH4)(2)SO4 solution does not vary significantly with solution pH. Ammonium nitrate results in a higher dissolution rate, due to the extra oxidizing power of the nitrate ion. The addition of an inhibitor, benzotriazole (BTA), reduces the copper dissolution rate significantly, even though the dissolution rate can be increased by rotating the copper disk. The dissolution of copper in stagnant aqueous ammonia solutions is controlled by oxygen diffusion at high NH4OH concentrations and by mixed kinetics at low NH4OH concentrations (10.3 wt %).

The influence of oppositely charged polyelectrolytes on the interlayer spacing of the lamellar liquid crystalline system hexadecyltrimethylammonium bromide/decanol/water was investigated by means of small angle X-ray diffraction and polarized microscopy. It could be demonstrated that a liquid crystalline phase was still formed by introducing a cationic polymer of low molecular weight into the lamellar structure. A disordering of the preformed structure and a decrease of the interlayer spacing occurred via penetration of the macromolecule between the hydrocarbon chains of the surfactant molecules. By using a ''penetration'' model for the disordering phenomena, ''folded'' and ''telescoped'' structures are discussed. The polyanion in a polyanion/polycation mixture gave the same structural change as when added alone.

The cathodic electrochemical behavior of nanosized sols of TiO2 on mercury electrodes in aqueous perchloric acid consists of two processes. The first, at more positive potential, is ascribed to the reduction of soluble Ti(IV) species. The nature of the second process, which does appear to involve the sols directly, has not been determined. However, it may involve the reduction of hydrogen ion adsorbed on the particles, as suggested by Heyrovsky, Jirkovsky, and Struplova-Bartackova.

Evaporation from microemulsions was investigated at room temperature in the system water-aerosol OT-cyclohexanone. The water/cyclohexanone weight ratio was varied and a minimum amount of surfactant was used to obtain a microemulsion in the samples used for the evaporation studies.Evaporation to 70 wt.% of the original weight took place with an approximately constant water/cyclohexanone ratio in the vapor, independent of the original water/cyclohexanone ratio. When the samples approached a water content of a few percent by weight, the cyclohexanone/water ratio was strongly increased in the vapor phase. These changes were assigned to differences in colloidal association structures and strong binding of the water molecules to the surfactant at low water content.

The electrochemistry of oxidizable and reducible substances solubilized in association colloids is reviewed. The systems considered are aqueous micelles and both oil and water continuous microemulsions. The emphasis is on the basic physical-chemical aspects of the electrochemical processes, and includes discussion of the effect of surfactant adsorption on the electrode as well as the effect of these colloidal media on the diffusion, discharge potential, and electron transfer mechanisms of the electroactive species.

The voltammetric behavior of cadmium dodecyl sulfate micelles in aqueous NaCl and NaNO3 solutions has been examined. In conjunction with potentiometric and conductance measurements, the critical micelle concentrations (CMC's) and apparent cadmium diffusion coefficients have been determined. The CMC's are not greatly affected by salt concentration up to 0.1 M. The apparent diffusion coefficients are satisfactorily accounted for by a two-layer diffusion model involving both micellar-bound and free cadmium(II) transport.

A monograph written for those working in the fields of colloid chemistry and electrochemistry.

Changes in the microstructure of oil-in-water microemulsions were identified electrochemically by using ferrocene derivatives, methyl viologen, and ferricyanide as the electroactive probes. Microdroplets as well as the bicontinuous microstructure were detected. This was accomplished by determining diffusion coefficients of the probes. Use of probes of different hydrophobicity/hydrophilicity and charge made it possible to investigate different microenvironments of microemulsions including oil, water, and surfactant/cosurfactant interface. Electrochemical reversibility of the probes was affected by the structure and appeared to reflect the ease of mobility across interphases. Reaction potential (E1/2) of the probes depended on the composition of the microemulsion.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic hydrolysis of phosphate esters in microemulsions. 4. p-Nitrophenyl diphenyl phosphate hydrolysis catalyzed by iodosobenzoate and some of its derivativesBeth A. Burnside, Barry L. Knier, Raymond A. Mackay, H. Dupont Durst, and Frederick R. LongoCite this: J. Phys. Chem. 1988, 92, 15, 4505–4510Publication Date (Print):July 1, 1988Publication History Published online1 May 2002Published inissue 1 July 1988https://doi.org/10.1021/j100326a050RIGHTS & PERMISSIONSArticle Views103Altmetric-Citations15LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (3 MB) Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic hydrolysis of phosphate esters in microemulsions. 3. Analysis of the hydrolysis products of p-nitrophenyl diphenyl phosphate via 31P NMRBeth A. Burnside, Linda L. Szafraniec, Barry L. Knier, H. Dupont Durst, Raymond A. Mackay, and F. R. LongoCite this: J. Org. Chem. 1988, 53, 9, 2009–2011Publication Date (Print):April 1, 1988Publication History Published online1 May 2002Published inissue 1 April 1988https://pubs.acs.org/doi/10.1021/jo00244a030https://doi.org/10.1021/jo00244a030research-articleACS PublicationsRequest reuse permissionsArticle Views297Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

We have continued our kinetics investigation of the iodosobenzoate (IBA) catalysis of the hydrolysis of p-nitrophenyl diphenyl phosphate (PNDP), in microemulsion media composed of hexadecane in water stabilized by cetyltrimethylammonium bromide and 1-butanol over a range of water mass fractions. We have examined two iodosobenzoic acid derivatives (5-nitro-2-iodosobenzoic acid and 5-octyloxy-2-iodosobenzoic acid) as catalysts. In addition, we have determined by31P FT-NMR techniques that the major product of the hydrolysis of PNDP, both in IBA catalyzed and in uncatalyzed media, is diphenylphosphate.