Dissertations / Theses on the topic 'Non ionic gemini surfactants'

Surfactants from the 'Triton' range, manufactured by Rohm and Haas, Germany, were used to study the adsorptive behaviour of non-ionic surfactants (of the alkyl polyoxyethylene type) from aqueous solution onto mineral oxide surfaces. The oligomeric distributions of the surfactants were characterised using the HPLC technique. Two gradients were used: a normal phase gradient was used to study the surfactants from non-aqueous solution; an unusual gradient, which could not be definitively categorised as either normal or reversed phase and which was developed at Brunel, was used to analyse surfactants directly from aqueous solution. Quartz was used as a model mineral oxide surface. The quartz surface was characterised using a range of techniques: scanning electron microscopy (SEM), X-ray photoelectron spectroscopy, X-ray fluorescence -analysis, Fourier transform-infra red spectroscopy and BET analysis. It was found that washing the quartz with concentrated HCI removed any calcium ions present on the surface and also removed 02- ions. Calcining the sample removed carbonaceous materials from the surface and also caused a decrease in the surface area. The quartz was shown to be non-porous by SEM and BET analysis. The adsorption experiments for this study were carried out using a simple tumbling method for which known ratios of surfactant in aqueous solution and quartz silica were mixed together for a known length of time. The amounts of surfactant present were measured using ultra-violet analysis and the HPLC techniques mentioned above. It was found that the smallest oligomers were adsorbed the most. An addition of salt to the system caused an overall increase in adsorption of the bulk surfactant, and increase in temperature caused an initial decrease in adsorbed amounts before the plateau of the isotherm and a final increase in bulk adsorption at the plateau of the isotherm. The oligomeric adsorption generally appeared to mirror the behaviour of the bulk surfactant. Atomic force microscopy (AFM), dynamic light and neutron scattering studies were used to analyse the character of the adsorbed surfactant layer. It was shown that the layer reached a finite thickness that corresponded to a bilayer of adsorbed surfactant. According to AFM data, this value of thickness was not consistent over the whole of the quartz surface.

The determination of surfactants in environmental surface water is required due to recent concern over possible adverse health effects that have been associated with them. This thesis is concerned with two aspects of the analysis of non-ionic and anionic surfactants in surface water. An HPLC phase-switching method has been developed in an attempt to overcome the problem of an interfering anionic species (thought to be humic acids) that masks the presence of any linear alkylbenzene sulphonate surfactants in river water samples. This problem has arisen following the development of an HPLC method for the determination of linear alkylbenzene sulphonates and alkylphenol ethoxylate surfactants in surface water in a previous research project. The phase-switching method allows the mobile phase to be diverted to either a C[1] or C[18] column or both. The linear alkylbenzene/humic acid portion was diverted to the C[18] column after elution from the C[1] column; the alkylphenol ethoxylate portion of the sample was then allowed to separate on the C[1] column as usual. Then the linear alkylbenzene / humic acid portion was separated on the C[18] column using a different mobile phase. The method works well with standards; however, with real samples it was not clear as to the identity of the peaks that may or not be linear alkylbenzene sulphonates. In addition, recent batches of the Spherisorb C[1] column were unable to adequately resolve the nonylphenol ethoxylate ethoxymers. The reason for this loss of resolution was investigated by elemental analysis and x-ray photoelectron spectroscopy. Bulk percentage carbon and surface carbon coverage both showed a similar trend. The earlier batch of Spherisorb column that produced the best resolution of nonylphenol ethoxylate ethoxymers had the lowest surface carbon coverage and the lowest percentage bulk carbon. Recent batches of the Spherisorb column along with columns from Supelco and Hypersil contained higher levels of carbon. These results suggest that resolution of the ethoxymers is due to the unreacted hydroxyl groups on the silica surface, and that the presence of the alkyl moiety actually hinders the process. In order to account for this a "pseudo reverse phase" mechanism has been invoked for this separation. The second section of this thesis involves the development of a new qualitative and quantitative method for the determination of nonylphenol ethoxylate surfactants in surface water by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. The sample was mixed with a concentrated solution of 2,5-dihydroxybenzoic acid or alpha-cyano-4-hydroxycinnamic acid as a matrix. Approximately 1 muL of the resulting solution was added to a stainless steel target and, after evaporation of the solvent, the target was placed into the mass spectrometer. The resulting spectra showed intense [M+Na][+] and [M+K][+] adducts for each ethoxymer group. Extracted samples from the River Don analysed by this method showed a similar characteristic envelope of peaks, corresponding to sodium and potassium adducts for nonylphenol ethoxylates. For quantitative determinations Triton X-100, an octylphenol ethoxylate surfactant, was added as an internal standard. A concentrated solution of lithium chloride was also added to produce much less complicated spectra consisting of solely [M+Li][+] adducts. Good linear relationships were seen for each individual ethoxymer over the entire distribution. The method showed excellent results for spiked surface water samples, but the concentrations of nonylphenol ethoxylates in recent samples were below the current limit of detection for this method of 100 mug/L.

The thin film pressure balance (TFPB) technique were used to study the stability of single foam films produced in the presence of n-alkyl polyoxyethylene (CnEOm) homologues. The results showed that films thin faster than predicted by the classical DLVO theory, which considers contributions from the van der Waals-dispersion and double-layer forces to the disjoining pressure of the film. The discrepancy may be attributed to the presence of hydrophobic force, the magnitude of which has been estimated using the Reynolds lubrication approximation. It has been found that the attractive hydrophobic force was substantially larger than the attractive van der Waals force, which may explain the faster film thinning kinetics. With a given non-ionic surfactant, the hydrophobic force decreased with increasing surfactant concentration, which explained the slower kinetics observed at higher concentrations and hence the increased foam stability. At concentrations where the hydrophobic force became comparable to or smaller than the van der Waals force, the foam films were stabilized by the increased elasticity of the foam films. The film elasticity of the surfactant solutions were measured using the oscillating drop analysis technique at different frequencies. The measurements were conducted in the presence of CnEOm surfactants with n=10-14 and m=4-8, and the results were analyzed using the Lucassen and van den Tempel model (1972). There was a reasonable fit between the experiment and the model predictions when using the values of the Gibbs elasticity calculated from the Wang and Yoon model (2006). From this exercise, it was possible to determine the diffusion coefficients (D) of the CnEOm surfactants. The D values obtained for CnEOm surfactants were in the range of 2.5x10-10 to 6x10-9 m2s-1, which are in general agreement with those reported in the literature for other surfactants. The diffusion coefficient decreased with increasing alkyl chain length (n) and increased with increasing chain length (m) of the EO group. These findings are in agreement with the results of the dynamic surface tension measurements conducted in the present work. The TFPB studies were also conducted on the foam films stabilized in the presence of a mixture of C12EO8 and sodium dodecylsulfate (SDS) at different ratios. The results showed that the hydrophobic force increased with increasing C12EO8 to SDS ratio. Thus, the former was more effective than the latter in decreasing the hydrophobic force and hence stabilizing foam films. The C12EO8 was more efficient than SDS in increasing the elasticity of the single foam films and stabilizing foams. The TFPB studies were also conducted in the presence of n-octadecyltimethyl chloride (C18TACl) and polymers, i.e., polyvinylpyrrolidone (PVP) and polystyrene sulfonate (PSS). The effect of polymer on the film elasticity was strongest in the presence of PSS, which can be attributed to the charge-charge interaction. Nano-sized silica and poly methyl methacrylate (PMMA) particles were used as solid surfactants to stabilize foams. It was found that the foam stability was maximum at contact angles just below 90o. The TFPB studies conducted with silica nano-particles showed that the kinetics of foam films became slower as the contact angle was increased from 30o to 77 o , indicating that foam films becomes more stable with more hydrophobic particles. The extra-ordinary stability observed with the hydrophobic silica nano-particles may be attributed to the possibility that the particles adsorbed on bubble surfaces retard the drainage rate and prevent the films to reach the critical rupture thickness (Hc). Confocal microscope and SEM images showed that hydrophobized nano-particles adsorbed on the surfaces of air bubbles, and that some of the nano-particles form aggregates depending on the particle size and hydrophobicity. The dynamic surface tension measurements conducted with PMMA and silica nano-particles showed that the latter has higher diffusion rates than the former, which may be due to the differences in particle size and hydrophobicity.
Ph. D.

Molecular simulations have become a mainstream tool of the physical sciences. In spite of their success in allowing us to understand the behaviour of matter at a molecular scale, current and foreseeable computational power limits the system sizes and time scales of ob- servation. Many common engineering scenarios, e.g., self-assembly of aqueous surfactant solutions, require access to large systems and long time scales. A coarse-graining method- ology, in which atoms and molecules are grouped into beads can be used to capture this behaviour using molecular simulation. However, the development of coarse-grained force fields for use in molecular simulation to study structural, thermodynamic and dynamical properties still remains a challenge. This challenge is the focus of the work presented in this thesis. Coarse-grained force fields obtained in this work were used in molecular simulations for a broad range of systems including: fluid phases of small molecules such as carbon dioxide, linear chains of alkanes, siloxanes and alcohols, to more complex aqueous systems of non- ionic surfactants, electrolytes, and ionic surfactants. The coarse-grained models were developed using a molecular-based equation of state of the Statistical Associating Fluid Theory (SAFT) family, based on the Mie (generalised Lennard-Jones) inter-molecular potential for the interactions between beads. This allows the structural, dynamical, and interfacial properties to be studied directly in molecular simulation. A transferable coarse-grained model for linear alkanes was developed. The carbon chains were used to form the backbone of a variety of organic molecules. Coarse-grained potentials for charged species were also obtained using an electrolyte version of the theory (SAFT-VRE) for use in molecular simulations. The coarse-grained models developed for the linear alkanes and aqueous electrolytes were subsequently used to establish a coarse- grained force field for the aqueous mixture of an important ionic surfactant: sodium dodecyl sulphate. The phase behaviour of the aqueous solutions of sodium dodecyl sulph- ate was studied with the coarse-grained models by molecular dynamic simulations, with emphasis on the structural properties of the different phases. Graphic processing units were also employed to perform large-scale simulations of the coarse-grained SAFT-γ Mie models of aqueous solutions of a non-ionic surfactant: tetraethylene glycol monodecyl ether. Despite the relative simplicity of the coarse-grained force fields developed using the SAFT-γ Mie equation of state, the models were robust and transferable. Properties that have not been considered in the original parameterisation procedure can be predicted, and the results are comparable with the more sophisticated and computationally demanding atomistic and united atom models. Therefore, the methodology developed in this work can be employed in a wide range of industrial and academic applications to help bridge the gap between the microscopic and macroscopic scales.

Les ions de taille nanométrique (nano-ions), tels que les clusters ioniques de bore, les polyoxométalates (POM) et les grands ions organiques, ont suscité un intérêt remarquable ces dernières années en raison de leur capacité à s’adsorber ou se lier à des systèmes chimiques électriquement neutres, tels que les molécules hôtes macrocycliques, les nanoparticules, les tensioactifs et les polymères, etc. Il a été démontré que ces processus d'adsorption ou de liaison sont induits par un phénomène médié par solvant, l'effet chaotropique, qui pousse le nano-ion de la masse d'eau vers une interface. Ainsi, l'eau d'hydratation de l'ion et de l'interface est libérée dans la masse d'eau, ce qui entraîne une restitution de la structure intrinsèque de l'eau. Cet effet est particulièrement fort pour les nano-ions. Ils sont par conséquent appelés ions superchaotropiques ou hydrophobes dans le prolongement des ions classiques (faiblement) chaotropiques tels que le SCN-. Tous les superchaotropes couramment étudiés, bien que chimiquement divers, partagent des caractéristiques physiques telles qu'une faible densité de charge et une grande polarisabilité. Les effets des nano-ions sur les auto-assemblages de tensioactifs non ioniques éthoxylés, les phases micellaires et bicouches, sont ici élucidés pour tirer des conclusions sur leur nature chaotropique et/ou hydrophobe. En combinant la diffusion aux petits angles des neutrons et des rayons X (SANS et SAXS), et les diagrammes de phase, les systèmes tensioactifs non ioniques/nano-ion sont examinés et comparés, du nanomètre à l'échelle macroscopique. Ainsi, il est montré que tous les nano-ions étudiés induisent un chargement électrique des assemblages de tensioactifs ainsi qu'une déshydratation des têtes de tensioactif non-ionique. En outre, les ions chaotropiques ou hydrophobes diffèrent dans leurs effets sur la forme micellaire. Les ions chaotropiques entraînent les micelles allongées de tensioactif non-ionique vers les micelles sphériques (augmentation de la courbure), tandis que les ions hydrophobes provoquent une transition vers les phases bicouches (diminution de la courbure). Il est conclu que les nano-ions superchaotropiques agissent comme des tensioactifs ioniques car leur ajout à des systèmes de tensioactifs non ioniques provoque un effet de charge. Cependant, les nano-ions et les tensioactifs ioniques sont fondamentalement différents par leur association avec l'ensemble des tensioactifs non ioniques. Le nano-ion s'adsorbe sur les têtes des tensioactifs non ioniques par effet chaotropique, tandis que le tensioactif ionique s'ancre dans les micelles entre les queues des tensioactifs non ioniques par effet hydrophobe. La comparaison des effets de l'ajout de nano-ions ou de tensioactifs ioniques à des tensioactifs non ioniques a été approfondie sur les mousses. Les mousses ont été étudiées en ce qui concerne l'épaisseur du film de mousse, le drainage dans le temps et la stabilité, respectivement en utilisant la SANS, l'analyse d'image et la conductométrie. Le POM superchaotropique testé (SiW12O404-, SiW) ne mousse pas dans l'eau contrairement au SDS classique de tensioactif ionique. Néanmoins, l'ajout de petites quantités de SiW ou de SDS à une solution moussante de tensioactif non ionique a permis d'obtenir des mousses plus humides avec une durée de vie plus longue. Entre-temps, l'épaisseur du film de mousse (déterminée en SANS) est augmentée en raison de la charge électrique des monocouches de tensioactifs non ioniques dans le film de mousse. Il est conclu que le comportement remarquable des nano-ions - ici sur les systèmes tensioactifs non ioniques - peut être étendu aux systèmes colloïdaux, tels que les mousses, les polymères, les protéines ou les nanoparticules. Cette thèse démontre que le comportement superchaotropique des nano-ions est un outil polyvalent qui peut être utilisé dans de nouvelles formulations de matériaux et d'applications de la matière molle
Nanometer-sized ions (nano-ions), such as ionic boron clusters, polyoxometalates (POMs) and large organic ions, have spawned remarkable interest in recent years due to their ability to adsorb or bind to electrically neutral chemical systems, such as macrocyclic host molecules, colloidal nano-particles, surfactants and polymers etc. The underlying adsorption or binding processes were shown to be driven by a solvent-mediated phenomenon, the chaotropic effect, which drives the nano-ion from the water bulk towards an interface. Thus, hydration water of the ion and the interface is released into the bulk resulting in a bulk water structure recovery. This effect is particularly strong for nano-ions. Therefore, they were termed superchaotropic or hydrophobic ions as an extension to classical (weakly) chaotropic ions such as SCN-. All commonly studied superchaotropes, though chemically diverse, share physical characteristics such as low charge density and high polarizability. Herein, the effects of nano-ions on ethoxylated non-ionic surfactant self-assemblies, micellar and bilayer phases, are elucidated to draw conclusions on their chaotropic and/or hydrophobic nature. By combining small angle scattering of neutrons and x-rays (SANS and SAXS), and phase diagrams, non-ionic surfactant/nano-ion systems are examined and compared, from the nanometer to the macroscopic scale. Thus, all studied nano-ions are found to induce a charging of the surfactant assemblies along with a dehydration of the non-ionic surfactant head groups. Furthermore, chaotropic and hydrophobic ions differ in their effects on the micellar shape. Superchaotropic ions drive the elongated non-ionic surfactant micelles towards spherical micelles (increase in curvature), whereas hydrophobic ions cause a transition towards bilayer phases (decrease in curvature). It is concluded that superchaotropic nano-ions act like ionic surfactants because their addition to non-ionic surfactant systems causes a charging effect. However, nano-ions and ionic surfactants are fundamentally different by their association with the non-ionic surfactant assembly. The nano-ion adsorbs to the non-ionic surfactant heads by the chaotropic effect, while the ionic surfactant anchors into the micelles between the non-ionic surfactant tails by the hydrophobic effect. The comparison of the effects of adding nano-ions or ionic surfactant to non-ionic surfactant was further investigated on foams. The foams were investigated regarding foam film thickness, drainage over time and stability, respectively using SANS, image analysis and conductometry. The tested superchaotropic POM (SiW12O404-, SiW) does not foam in water in contrast to the classical ionic surfactant SDS. Nevertheless, addition of small amounts of SiW or SDS to a non-ionic surfactant foaming solution resulted in wetter foams with longer lifetimes. Meanwhile, the foam film thickness (determined in SANS) is increased due to the electric charging of the non-ionic surfactant monolayers in the foam film. It is concluded that the remarkable behavior of nano-ions – herein on non-ionic surfactant systems – can be extended to colloidal systems, such as foams, polymers, proteins or nanoparticles. This thesis demonstrates that the superchaotropic behavior of nano-ions is a versatile tool to be used in novel formulations of soft matter materials and applications

Thesis (Honors)--Ohio State University, 2005.
Title from first page of PDF file. Document formattted into pages: contains vi, 78 p.; also includes graphics. Includes bibliographical references (p. 62-63). Available online via Ohio State University's Knowledge Bank.

The objectives of this study were two-fold: firstly to add to existing knowledge about the reaction of peracid with both iodide and sulfides in the presence of micelles (anionic and non-ionic) and α-cyclodextrin. The reaction between iodide and peracid had previously been studied only at 25°C in non-ionic, anionic micellar and alpha cyclodextrin; while the reaction of sulfides and peracid had only been investigated in the presence of α-cyclodextrin at one temperature. This study has investigated the previously undetermined effect of temperature on these reactions and how changes in temperature can affect the process of reactants binding to the micelle or cyclodextrin catalyst. The second objective was to obtain quantitative information about reactivity in ordered aqueous media such as micellar systems and cyclodextrins, and find out how these media can affect and control these reactions. This might have implications for fields such as cell biology, specifically for process occurring in living cells since both cyclodextrins and micelles might be considered simple models for protein and membranes in terms of their hydrophobicity. In addition, little information is known about bimolecular reactions involving two neutral reactants in non-ionic micelles where only the hydrophobic interaction is likely to influence the reaction due to the absence of charge-charge interaction. A kinetic and thermodynamic investigation of the reactions between peracids and different reductants i.e. iodide and series of aryl alkyl sulfides in presence non-ionic micelle and a- cyclodextrin is reported in this work. The kinetics were conducted by monitoring spectrophotometrically the increase or decrease in the absorbance due to formation of triioidide or disappearance of sulfides respectively, and absorbance versus time plots were fitted to nonlinear equation in order to obtain the observed pseudo first order rate constants. For reactions carried out in micellar systems the kinetic data were treated using the multiple micellar pseudophase model developed by Davies which considers the partition of reactants between water in the bulk aqueous phase and that in the micellar pseudophases. Important parameters in this model include the binding constant of reactants to Brij (non-ionic micelle) and kn. (reaction rate in micelle). For reactions in α-cyclodextrin, data was fitted to rate equations containing first and second order dependencies on cyclodextrin using non linear regression techniques. The work was carried out in the presence of 0.003 M nitric acid as reaction medium. The effect of inorganic electrolytes (sodium nitrate, sulfate, actetate, perchlorate and chloride) on the rate of oxidation of iodide in the absence and presence of non-ionic surfactant brij-35 was also studied. The critical micelle concentration (CMC) of the surfactants was determined using kinetic techniques and was found to be inversely proportional to the salt concentration and also to the temperature. The CMC was also found to decrease as the length of the hydrophobic part of the Brij surfactants was increased, possibly due to the decrease of interfacial energy on micellization, which generally increases in with increasing hydrophobic chain length. It was shown from analysis of the kinetic data that all non-ionic micelles in the (absence of salts) and a-CD studied in this work enhanced the rate of the iodide oxidation by MCPBA and that the rate showed saturation type kinetics. Sulfate ions were shown to accelerate the reaction further, whereas perchlorate caused an inhibition of the iodide oxidation (compared to the reaction only in nitric acid) in presence of Brij-35, but an increase in the presence of α-cyclodextrin. For the oxidation of sulfides by MCPBA in micelles and a-CD the observed rate increases to a maximum with increasing micelle or a-CD concentration and then subsequently declines. In the case of sulfide oxidation by the anionic peracid, peroxymonosulfate (PMS), there was only inhibition in the rate, due to separation of reactants. The effect of temperature on both rate and equilibrium processes for these systems was determined over the range 15 to 35°C. The results showed a linear decrease in the binding of metachloroperbenzoic (MCPBA) acid and aryl alkyl sulfides to both micelle and a-CD with increasing the temperature. The thermodynamic and activation parameters for the reactions were determined by using Van't Hoff and Eyring plots. Comparison of the micellar association constants of MCPBA and the apparent micellar association constant of the transition state for the reaction with iodide, suggested that orientational restriction imposed on the peracid by Brij-35 are similar to that in the transition state. For the same reactions carried out in α-cyclodextrin at different temperatures it was determined that the binding constant enthalpy and entropy of substrates, (peracid and iodide) are more negative than that obtained in the presence of brij-35 which indicates that stronger interactions are involved and more restriction imposed on the reactant in presence of a-CD compared to brij-35.A similar approach was employed for the reaction of series of aryl alkyl sulfides with peracids (PMS and MCPBA) in presence of Brij-35 and a-CD. The aryl alkyl sulfides can form both 1:1 and 2:1 host: guest complexes in cyclodextrin; the 2:1 inclusion complexes for some sulfides were larger than the 1:1 complexes, indicating cooperative binding, with the driving force for this possibly being a substrate induced dipole-dipole interaction between the two cyclodextrin molecules. Linear free energy studies indicate that the catalytic species is the bound peracid reacting with the unbound sulfides; sulfide binding results in steric inhibition of the reaction. The reaction of the non-binding PMS with sulfides results only in inhibition as cyclodextrin concentration is increased. The enthalpy and entropy for sulfide oxidation by peracids was calculated by means of a Van't Hoff plot. The reaction in a-CD associated with more negative entropy and enthalpy for the inclusion 2:1 while for 1:1 some substrates associated with positive entropy and small negative enthalpy while other show the usual behaviour observed for complex formation (negative values for both enthalpy and entropy).In all studied reactions (related reactions) there were good relationships between enthalpy and entropy (isokinetic relationships or enthalpy-entropy compensation). Whilst in some cases it is difficult to explain why enthalpy-entropy compensation might be observed, we have suggested that in the case of binding of sulfides to cyclodextrin these plots can act as probes into the orientation of the substrate within the cyclodextrin cavity. The nature of the catalytic mechanism for the reactions of peracids with sulfides and iodide in the presence of micelles and α-cyclodextrin was examined by comparing the transition state stabilisation parameters, KTsi, for the same reaction in the two catalytic systems. It was found that for three out of five sulfides the degree of transition state stabilisation was almost identical in both Brij-35 and α-cyclodextrin, perhaps suggesting the same catalytic mechanism in each system; this could be via either decreased stabilisation of the peracid ground state in the absence of a protic solvent and/or the prevention of significant charge development in the transition state as a result of an intramolecular proton transfer step involving the peracid that is facilitated by the absence of water. Other possibilities exist, such as general acid catalysis, though these would be more dependent on the nature of the catalytic system. There was a less clear relationship for iodide.

This work is focused on the study of interaction between hyaluronan and high-biocompatible amphiphilic molecules. Using fluorescent probe method, screening of the interaction of cationic lipid 1,2-dipalmitoyl-3-trimethylammonium-propane (DPTAP), mixture of this cationic lipid with zwitterionic lipid, 1,2-dipalmitoyl-sn-glycero-3-phosphochloline (DPPC), with hyaluronan, both native and hydrophobically modified was carried out. Results showed the self-aggregation of DPPC and DPTAP independently on lipids ratio in the mixture and the interaction of DPTAP and DPPC/DPTAP aggregates with hyaluronan at specific ratio of DPTAP and hyaluronan concentration. Physical properties of formed membranes and the influence of cholesterol were also investigated at different DPPC and DPTAP concentration ratio. Last but not least, the non-ionic surfactant-DPPC systems were studied, namely, the size of the formed aggregates, the thermodynamics of solubilisation and the interaction with native hyaluronan.

Synthèse de nouveaux tensioactifs perfluorés ou hydrogènes dérivant d'un acide carboxylique, d'un chlorure d'acide ou d'une amine. Détérmination des propriétés physicochimiques des systèmes eau/agent de surface (concentration critique micellaire, tension superficielle)

Atualmente, decorrente da cultura estética onde há o culto aos corpos esbeltos com aparência saudável e pele lisa, macia e viçosa, a hidrolipodistrofia ginóide, conhecida como celulite, tem sido um dos desafios para os dermatologistas e cirurgiões plásticos. Assim, temse testado diferentes formas de tratamentos entre as quais estão aplicações de cremes à base de xantinas visando a atenuação dos sintomas. O conhecimento das propriedades físicoquímicas de tais formulações é essencial para otimizar as condições de produção e liberação do ativo na pele, além de prover elegância cosmética do produto desenvolvido. Os objetivos desse trabalho foram obter e avaliar a estabilidade de emulsões O/A contendo fase líquida cristalina, adicionada de cafeína, para aplicação no tratamento da hidrolipodistrofia ginóide, bem como avaliar o perfil de liberação da substância ativa in vitro com intuito de determinar sua disponibilidade. A emulsão O/A contendo como fase oleosa, óleos vegetais naturais (óleo de urucum, de café e de melaleuca) foi desenvolvida através da utilização do Sistema Equilíbrio Hidrófilo- Lipófilo (EHL). Utilizando os tensoativos não-iônicos Ceteareth 5 e Steareth 2 nas concentrações de 10,0 e 15,0% foi possível obter fases líquidas cristalinas lamelares. A adição de cafeína a 1,0% foi conseguida em emulsão contendo 15,0% da mistura de tensoativos e com auxílio na solubilização através do uso de benzoato de sódio na mesma concentração (1,0%). As emulsões foram consideradas estáveis segundo as condições experimentais e parâmetros analisados. O perfil de liberação da substância ativa apresentou fase inicial de liberação mais rápida seguida de outra mais lenta. A eletroforese capilar mostrou-se ferramenta mais adequada para quantificação do ativo. Os resultados sugerem que os cristais líquidos lamelares estejam atuando provavelmente como veículo de liberação lenta.
Nowadays, due to aesthetic culture that there is the cult to slim body with health appearance and smooth, vigorous skin, the gynoid hydrolipodystrophy, known as cellulite, has been one of the challenges for dermatologists and plastic surgeons. Thus, different kinds of treatments have been tested, and among them, the application of xantines-based creams in order to attenuate the symptoms. The knowledge of the physicochemical properties of such formulations is essential to optimize the production conditions and active skin delivery, besides promoting cosmetic elegance of the developed product. The aims of this research were to attain and to evaluate the stability of O/W emulsions containing liquid crystalline phase, with the addition of caffeine, to be used on the gynoid hydrolipodystrophy treatment, as well as evaluate the release profile of the active in vitro in order to determine its availability. The O/W emulsion containing natural vegetable oils (annatto oil, coffee oil and tea tree oil) as oily phase was developed through the utilization of Hydrophilic Lipophilic Balance System (HLB). When using the non-ionic surfactants Ceteareth 5 and Steareth 2 in the 10.0 and 15.0% concentrations it was possible to obtain lamellar liquid crystalline phases. The addition of caffeine 1.0% was attained in emulsion containing 15.0% of the surfactant mixture and its solubility was improved through the sodium benzoate use in the same concentration. The emulsions were considered stable according to the experimental conditions and evaluated parameters. The release profile of the active agent presented a faster initial phase followed by a slower one. The capillary electrophoresis showed a more suitable tool to quantify the active. The results suggest that the lamellar liquid crystals are probably acting as slow delivery vehicle.

Les propriétés de miscibilité en milieu aqueux de couples de tensioactifs non ioniques, dont la partie hydrophobe est respectivement hydrogènée et fluorée, sont étudiées. La variable essentielle est la longueur de la chaîne fluorée. Outre les diagrammes de phrase, une étude extrêmement complète des systèmes très dilués a été effectuée à l'aide de mesures de tension superficielle

Cette thèse présente une étude de la formation des phases lyotropes et des micelles dans des systèmes binaires de tensioactifs ioniques en solvants polaires non aqueux. Phases lyotropes: après une étude bibliographique des phases lyotropes et de la théorie de la frustration géométrique, les systèmes binaires étudiés sont présentés et la méthode originale d'étude des phases lyotropes ordonnées par diffraction des rayons X aux petits angles est décrite. L'existence de phases lyotropes est clairement mise en évidence en milieu polaire non aqueux même si l'effet solvophobe est beaucoup plus faible que dans l'eau et le solvant aprotique. La structure des phases cristal-liquide et leur séquence en fonction de la concentration sont celles prévues par la théorie géométrique, même lorsque dans l'eau le polymorphisme des phases ordonnées est plus complexe. La densité d'énergie de cohésion du solvant joue un rôle important sur le domaine d'existence des phases et sur la valeur de leurs paramètres toujours plus petits que dans l'eau. L'influence du détail chimique, longueur de la chaine aliphatique, tête polaire et contre-ion, est discutée. Micellisation : après une étude bibliographique concernant le modèle micellaire, l'approche thermodynamique d'auto-association de molécules de tensioactif et la détermination de la structure micellaire par diffusion centrale des neutrons, les systèmes étudiés et la méthode employée sont présentés. La micellisation est abordée uniquement dans le formamide avec divers surfactants. Les résultats de la micellisation sont présentés et analysés pour montrer l'influence de la longueur de la chaîne, de la tête polaire et du contre-ion. Les micelles sont toujours trouvées plus petites que dans l'eau et plus chargées. Un fort étalement en taille des micelles est mis en évidence par modélisation des courbes expérimentales et est confirmé par l'approche thermodynamique. La faible valeur de l'énergie interfaciale cur/solvant et les densités surfaciques de charges en sont responsables

Détermination des diagrammes de phase de systèmes à base de poly(oxyethylène) ether dodécyle et de faibre quantité de décane, à l'aide de la méthode isotherme et par balayage automatique en température. Étude structurale des zones cristallines par diffraction des rayons X

Research in the field of non-viral gene delivery has demonstrated that a deeper understanding of the fundamental processes of nanoparticle assembly is required in order to improve their efficacy. While gemini nanoparticles (gemini NPs) and other non-viral delivery systems have been vigorously characterized using several techniques, our knowledge is still incomplete. The first objective of this study was the development of new methodology using fluorescence correlation spectroscopy (FCS) to investigate the stages of gemini NPs assembly. It was demonstrated that by labeling the plasmid, different stages of gemini NP assembly from the gemini-plasmid pre-complex (GP) to the final gemini nanoparticle (or gemini-plasmid-lipid complex; GPL), could be studied. Based on diffusion coefficients and particle numbers extrapolated from the autocorrelation function (ACF), FCS was able to determine that each phase of assembly had distinct characteristics. The FCS study using 12-3-12 gemini surfactant showed that both the diffusion coefficient and particle number of GPs (0.98??0.31 x 10-12 m2/s) was significantly lower than the final GPL (3.11??0.41 x 10-12 m2/s). Based on the Stokes-Einstein equation the particle size was calculated to be 300-500 nm for GP and 200-300 nm for GPLs. The raw intensity histograms showed that both GPs and GPLs are composed of multiple plasmids. Furthermore the study showed that the final GPLs contain fewer plasmids compared to the intermediate GP. FCS results were validated by using existing characterization methods including dynamic light scattering (DLS), zeta potential and dye exclusion assays. The second objective involved the detailed characterization of gemini NP. Nine different gemini surfactants and two different phospholipids were used in a systematic study to assess the effect of gemini surfactant and lipid structure on the final morphology of gemini NP. The study revealed that gemini surfactant structure had a strong effect on structure of GP intermediates, but addition of phospholipids resulted in the formation of uniform gemini NPs. Based on the results of this study a new model for GP and GPL assembly is proposed based on the formation of supramolecular aggregates of gemini-plasmids, governed by gemini surfactant chemical structure, and dispersed by phospholipids to form GPLs.

碩士
國立臺灣科技大學
化學工程系
98
This study deals with the problems of latex particles size control and stability for semi-batch styrene/2-ethylhexyl acrylate emulsion polymerization. The effects of the type and concentration of non-ionic surfactants in the initial reactor charge and the monomer emulsion feed are the major focus of this work. The particle size decreases with increasing the weight ratio of styrene in total monomer weight. When the weight ratio of styrene greater than percent of ten, the particle size variation is not evident. The concentration of surfactant during the particle nucleation period plays an important role. Experimental data show that the particle size decreases with increasing the concentration of surfactants. But the concentration of non-ionic surfactant (#5105) is the most important parameter. Moreover, changing the concentration of non-ionic surfactants (D-400E and #5091) do not change the particle size significantly, but the surfactants protect the colloid and maintain particle stability. About latex particle stability, we measure the amount of scrap to analyze the relationship between three variables and particle stability. Experimental data show that the latex particle stability depends on the type of non-ionic surfactants. The concentration of surfactant increases with decreasing the amount of scrap. The influence the non-ionic surfactant (#5105) in the initial reactor is significant. Moreover, the slight influence of the concentration of nonionic surfactant (D-400E and #5091) on the latex stability was observed. About the different molecular weight non-ionic surfactants having the poly(ethylene glycol) structure, the capability of non-ionic surfactant in protecting particles increases with increasing length of the polymer chain.

Gemini surfactants are versatile gene delivery agents because of their ability to bind and compact DNA and their low cellular toxicity. The aim of my dissertation work was to develop non-invasive mucosal formulations of novel amino acid-substituted gemini surfactants with the general chemical formula C12H25(CH3)2N+-(CH2)3-N(AA)-(CH2)3-N+(CH3)2-C12H25 (AA= glycine, lysine, glycyl-lysine, lysyl-lysine). These compounds were formulated with a model plasmid DNA, encoding for interferon-γ and green fluorescent protein, in the presence of helper lipid, 1,2 dioleyl-sn-glycero-phosphatidyl-ethanolamine. Formulations were assessed in Sf 1 Ep epithelial cells. Among the novel compounds, plasmid/gemini/lipid (P/G/L) nanoparticles formulated using glycine- and glycyl-lysine substituted gemini surfactants achieved significantly higher gene expression than the parent unsubstituted compound. The key physicochemical properties, e.g. size, surface charge, DNA binding, and toxicity of P/G/L complexes were correlated with transfection efficiency. The presence of amino-acid substitution did not interfere with DNA compaction and contributed to an overall low toxicity of all P/G/L complexes, comparable to the parent gemini surfactant. A cellular uptake mechanistic study revealed that both clathrin- and caveolae-mediated uptake were major uptake routes for P/G/L nanoparticles. However, amino acid substitution in the gemini surfactant imparted high buffering capacity, pH-dependent increase in particle size, and balanced DNA binding properties. These properties may enhance endosomal escape of P/12-7NGK-12/L resulting in higher gene expression. Finally, the P/G/L complexes were incorporated into an in-situ gelling dispersion containing a thermosensitive polymer, poloxamer 407, and a permeation enhancer, diethylene glycol monoethyl ether (DEGEE). A 16% w/v poloxamer concentration produced a dispersion that gelled at body temperature and exhibited sufficient yield value to prevent formulation leakage from the vaginal cavity. The formulations were prepared with a model plasmid, encoding for red fluorescent protein, and administered topically to rabbit vagina. In agreement with our in vitro results, confocal microscopy revealed that glycyl-lysine substituted gemini surfactant exhibited higher gene expression compared to the parent unsubstituted gemini surfactant. This provided proof-of-concept for use of amino acid-substituted gemini surfactant in non-invasive mucosal (vaginal) gene delivery systems with potential therapeutic applications. These formulations will be developed with therapeutically relevant genes to assess their potential as genetic vaccines. In addition, new gemini surfactants will be developed by grafting other amino acids via glycine linkage to retain conformation flexibility and enhance endosomal escape of DNA complexes for higher transfection efficiency.

The EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centres and universities
The objective of this study is to investigate the influence of three different types of surfactants (i) anionic sodium dodecyl sulphate (SDS), (ii) cationic (hexadecyltrimethylammonium bromide (CTAB), and (iii) non-ionic: Triton X-100 (Polyethylene glycol tert-octylphenyl ether) and the effect of surfactant concentration on ultrafiltration of colloidal silica nanoparticles. Due to the high surface area to volume ratio of nanoparticles, the role of surface interactions on the stability of silica suspensions is enhanced. The effects of adsorption of surfactants are studied by means of static light scattering and zeta potential measurements. The strongest particle-surfactant interaction is observed between oppositely charged CTAB with silica, followed by TX-100 and SDS. An ultrafiltration hollow-fibre membrane is used in a semi-dead end configuration to perform filtration of silica suspension with varying surfactant concentration to critical micelle concentration (CMC) ratio, csurfactant/ccmc in a flux-step mode. The effect of surfactants and process conditions (flux) on filtration process have been compared by evaluating the critical flux and total fouling rate. The occurrence of critical flux and evolution of fouling rates are also strongly affected by the surfactant concentration. This difference in filtration performance is attributed to various competing and complementary mechanisms: electrostatic and hydrophobic interactions between surfactant-membrane surface, electrostatic and hydrophobic interactions between particles as well as the hydrodynamic effect of fluid motion towards the membrane. A comparison of the overall fouling potential for surfactant-silica systems showed that SDS-silica systems showed fouling rates of an order of magnitude higher than those of CTAB-silica and TX100-silica systems at the same csurf/cCMC ratio. This was an unexpected finding, as we would expect stable colloidal systems such as SDS-silica systems would exhibit lower fouling than unstable colloidal systems (e.g. CTAB-silica systems).
European Commission

碩士
元智大學
機械工程學系
106
There are many types of surfactants, and water-soluble surfactants account for more than 70% of the total, of which nonionic surfactants account for about 25%. The nonionic surfactant is a surfactant having a main hydrophilic group in the molecule which contains an ether group which is not dissociated in an aqueous solution, has excellent wetting and washing functions, and can be used together with other ionic surfactants. The non-ionic active agent is derived from a polyol, and its aqueous solution has an interface activity and can be synthesized from oil-soluble to water-soluble. Used in the reflow oven of the printed circuit board process, after the tin is bonded to the solder ball, the waste liquid produced by the cleaning of the board is cleaned by the cleaning agent. The chemical oxygen demand (COD) of the waste liquid is up to 1.5 million ppm. The general chemical coagulation and biological treatment wastewater treatment plants cannot handle them, and the risk of arbitrary disposal is high. In this study, the high-COD waste liquid is treated by the existing process, and the treatment target can be accommodated in the wastewater field. The value is set to 100,000 ppm or less, and the removal rate needs to be over 94%. The activated carbon adsorption method is pretreated and electrocatalyzed. Oxidation method, the test results are in line with the treatment specifications of the wastewater field.

Linear covalently closed (LCC) DNA minivectors serve to be superior to conventional circular covalently closed (CCC) plasmid DNA (pDNA) vectors due to enhancements to both transfection efficiency and safety. Specifically, LCC DNA minivectors have a heightened safety profile as insertional mutagenesis is inhibited by covalently closed terminal ends conferring double-strand breaks that cause chromosomal disruption and cell death in the low frequency event of chromosomal integration. The development of a one-step, E. coli based in vivo LCC DNA minivector production system enables facile and efficient production of LCC DNA minivectors referred to as DNA ministrings. This novel in vivo system demonstrates high versatility, generating DNA ministrings catered to numerous potential applications in gene therapy and vaccine development. In the present study, numerous aspects pertaining to the generation of gene therapeutics with LCC DNA ministrings have been explored with relevance to both industry and clinical settings. Through systematic assessment of induction duration, cultivation strategy, and genetic/chemical modifications, the novel in vivo system was optimized to produce high yields of DNA ministrings at ~90% production efficiency. Purification of LCC DNA ministrings using anion exchange membrane chromatography demonstrated rapid, scalable purification of DNA vectors as well as its potential in the separation of different DNA isoforms. The application of a hydrogel-based strong Q-anion exchange membrane, with manipulations to salt gradient, constituted effective separation of parental supercoiled CCC precursor pDNA and LCC DNA. The resulting DNA ministrings were employed for the generation of 16-3-16 gemini surfactant based synthetic vectors and comparative analysis, through physical characterization and in vitro transfection assays, was conducted between DNA ministring derived and CCC pDNA derived lipoplexes. Differences in DNA topology were observed to induce differences in particle size and DNA protection/encapsulation upon lipoplex formation. Lastly, the in vivo DNA minivector production system successfully generated gagV3(BCE) LCC DNA ministrings for downstream development of a HIV DNA-VLP (Virus-like particle) vaccine, thus highlighting the capacity of such system to produce DNA ministrings with numerous potential applications.