Les émulsions sont très utilisées dans le domaine des cosmétiques, notamment pour les crèmes et les lotions. En fonction de leur composition, elles présentent diverses propriétés en matière de stabilité, de texture, de microstructure et de macrostructure. Il n’existe pas, à l’heure actuelle, d’étude dans la littérature qui se soit intéressée à l’effet de la composition sur ces différentes propriétés et aux relations qui peuvent exister entre celles-ci, tout en mettant en œuvre une maîtrise de la formulation. Pour répondre à cette double problématique, quatorze émulsions huile-dans-eau ont été formulées, avec un protocole maîtrisé, pour lesquelles les concentrations en phase grasse, en gomme acacia et en xanthane varient. Des solutions de xanthane et de gomme acacia ont également été préparées pour comparer l’effet des gommes en émulsion et en phase aqueuse seule. Les produits ont été ensuite caractérisés, de façon la plus complète et objective possible, pour mettre en évidence l’influence de la composition sur les propriétés de l’émulsion et leurs interactions. De nombreux paramètres ont ainsi été collectés par : analyse sensorielle, des observations microscopiques et des mesures en granulométrie laser, des mesures rhéologiques et mécaniques. On peut en conclure que chacun des paramètres de l’émulsion impacte ses propriétés, avec des différences notables, la teneur en phase grasse étant, globalement, prépondérante. Des relations entre l’ensemble des données ont été mises en évidence et permettent de proposer des hypothèses quant à l’impact de la formulation sur les propriétés tactiles des crèmes cosmétiques. / Emulsions are widely used in cosmetics. Depending on their composition, they exhibit various properties in terms of stability, texture, microstructure and macrostructure. At the present time, there a few to no studies in the literature interested in the effect of the emulsions composition on these different properties and the existing link between these characteristics that are implementing a command of the formulation. To address this dual problem, fourteen oil-in-water emulsions were formulated, with a controlled formulation protocol, for which the concentration of oil phase, acacia gum and xanthan gum evolve. Solutions of xanthan and acacia gums were also prepared to compare the effect of the gums on emulsions to the one on aqueous phase alone. The products were then characterized, in the most complete and objective way possible, to illustrate the influence of the composition on the properties of the emulsions and how these interact. Numerous parameters were collected through : ensory analysis, mcroscopic observations and static light scattering measurements, rhlogical and instrumental texture analyses. t can be concluded that the emulsions are well differentiates and that each of the emulsion parameter impacts its properties with significant differences, the oil phase content being preponderant overall. elationships between the data set were highlighted and suggest hypotheses about the impact of the formulation on the tactile properties of cosmetic creams.

L’encapsulation est une technique employée couramment par le milieu industriel, notamment dans le domaine du médical, de la parfumerie ou de la cosmétique. Afin de répondre aux attentes et de proposer des capsules modulables pour tous types d’applications, des capsules de type coeur-écorce ont été élaborées au cours de cette thèse. Elles sont obtenues à partir d’émulsion dont le coeur huileux est enrobé par une coque de silice, via la minéralisation de l’interface eau-huile. Les émulsions de Pickering, stabilisées par des particules colloïdales, sont particulièrement stables et intéressantes pour cette étude. Le but de cette thèse est de comprendre, dans un premier temps, les mécanismes fondamentaux impliqués dans le processus de fabrication. Cela a permis d’élaborer, par la suite, des matériaux hybrides complexes à différentes échelles, du micrométrique au nanométrique,mais également d’établir les mécanismes de libération par un stimulus externe. Enfin, une encapsulation maîtrisée permet d’allier stabilité au stockage et destruction rapide ou contrôlée à l’utilisation. Ainsi, par diverses méthodes définies dès la formulation de l’émulsion initiale, le contenu huileux des capsules peut être libéré de manière provoquée par une action mécanique ou par l’augmentation de la température (macroscopique ou local par hyperthermie magnétique). / Encapsulation is a technique used in the industry, in particular in the field of medical,perfumery or cosmetics. In order to meet the expectations and propose adaptable capsules for all types of applications, core-shell capsules type were developed during this thesis.There were based on emulsions science with an oily core coated by a silica shell,synthetized by sol-gel chemistry at the oil-water interface. Pickering emulsions, which are emulsions stabilized by colloidal particles, are particularly stable and interesting for this study. The aim of this thesis is to understand, at first, the fundamental mechanisms involved in the manufacturing process. This made it possible to develop complex hybrid materials at different scales, from micrometric to nanometric, but also to establish the releasing mechanisms by an external stimulus. Thanks to a controlled encapsulation, it is possible to combine stability (storage) and rapid or controlled destruction when used. Thus, by various method, defined from the formulation of the initial emulsion, the releasing of the oily contentcan be caused by mechanical action or by an temperature increased (macroscopically orlocally by magnetic hyperthermia).

The aims of this thesis were two-fold: A) To use high internal phase emulsion (HIPE) templated materials to produce a chromatographic stationary phase for the size separation of engendered nanoparticles (NPs). B) To produce well characterised lanthanide doped polymer NPs with a potential use as analytical standards. Initially, silica materials were prepared from oil-in-water HIPEs by a two stage acid/base catalysed sol gel process. As well as presenting the expected macroporosity typical of HIPE templated materials, it was also found that micro- and meso-porosity could be influenced by surfactant choice and reaction with iron (III) chloride or copper (I) chloride which had been included in the HIPE. However, the resulting silica materials were deemed inappropriate for the desired chromatography. Monolithic columns were prepared from HIPE templated polymers (polyHIPEs) and incorporated into a HPLC system. Poly(styrene-co-divinylbenzene) and poly(ethylene glycol dimethacrylate) polyHIPE columns were able to separate sub-micron polystyrene latexes, detected by UV absorption, and dysprosium doped polystyrene latex particles and gold nanoparticles detected by inductively coupled plasma mass spectrometry (ICP-MS).Dysprosium, gadolinium and neodymium doped polystyrene NPs were prepared by micro-emulsion polymerisation. Particle size was controlled (over a 40 – 160 nm range) by tailoring of surfactant and initiator concentrations. Particles were characterised by dynamic light scattering, differential centrifugal sedimentation, transition electron microscopy and hydrodynamic chromatography (HDC)-ICP-MS. Also, particle surface change, lanthanide content and solids content were analysed. The latter two appear related to particle size. As far as the author is aware there are no cases of the use of polyHIPE columns size separation in the literature. Nor are there any cases of encapsulation of metals within polymer nanoparticles by micro-emulsion polymerisation reported.

This study (Wassell & Young 2007; Wassell et al., 2010a) shows that behenic (C22:0) fatty acid rich Monoacylglycerol (MAG), or its significant inclusion, has a pronounced effect on crystallisation (Wassell et al., 2010b; 2012; Young et al., 2008) and interfacial kinetics (3.0; 4.0). New interfacial measurements demonstrate an unusual surface-interactive relationship of long chain MAG compositions, with and without Polyglycerol Polyricinoleate (PGPR). A novel MAG synthesised from Moringa oleifera Triacylglycerol (TAG) influenced textural behaviour of water-in-oil (W/O) emulsions and anhydrous TAG systems (4.0: 5.0; 6.0). Emulsifier mixtures of PGPR and MAG rich in C18:1 / 18:2 and C16:0 / C18:0 do not decrease interfacial tension compared with PGPR alone. Only those containing MAG with significant proportion of C22:0 impacted interfacial behaviour. A mixture of C22:0 based MAG and PGPR results with decreasing tension from ~20°C and is initially dominated by PGPR, then through rearrangement, the surface is rapidly dominated by C22:0 fatty acids. A Moringa oleifera based MAG showed unusual decreased interfacial behaviour not dissimilar to PGPR. All other tested MAG (excluding a C22:0 based MAG), irrespective of fatty acid composition resulted with high interfacial tension values across the measured temperature spectrum (50°C to 5°C). A relative decrease of interfacial tension, with decreased temperature, was greater, the longer the chain length (Krog & Larsson 1992). Moreover, results from bulk and interfacial rheology showed that the presence of C22:0 based MAG has a pronounced effect on both elastic modulus (G’) and viscous modulus (G’’). Through a multidisciplinary approach, results were verified in relevant product applications. By means of ultrasonic velocity profiling with pressure difference (UVP-PD) technique, it was possible to examine the effect of a C22:0 based MAG in an anhydrous TAG system whilst in a dynamic non-isothermal condition (3.0). The non-invasive UVP-PD technique conclusively validated structural events. The application of a Moringa oleifera based MAG in low TAG (35% - 41%), W/O emulsions, results in high emulsion stability without a co-surfactant (PGPR). The bi-functional behaviour of Moringa oleifera based MAG is probably attributed to miscibility (Ueno et al., 1994) of its fatty acids, ranging ~30% of saturated fatty acids (SAFA), with ~70% of C18:1 (5.0). It is concluded that the surface-interactive behaviour of Moringa oleifera based MAG, is attributed to approximately 10% of its SAFA commencing from C20:0. When examined separately and compared, results showed that physical effect of a Moringa oleifera based MAG was not dissimilar to PGPR, influencing the crystallisation kinetics of the particular anhydrous TAG system. When either was combined with a C22:0 rich MAG, enhanced gelation onset and strong propensity to form dendrite structure occurred (5.0). Macrobeam and synchrotron radiation microbeam small angle x-ray diffraction (SR-μ-SAXD) was utilized (6.0) to assess behavior of C22:0 rich MAG, with and without PGPR (Wassell et al., 2012). The C22:0 based MAG combined with PGPR promoted TAG crystallisation as observed by differential scanning calorimetry (DSC). Polarised optical microscopy (POM) observations indicated that C22:0 based MAG eliminates formation of large crystal aggregates, resulting in the likely formation of tiny Pickering TAG / MAG crystals (6.0). It is concluded that the presence and interactive behaviour of Pickering surface-active MAG, is strongly linked to increased fatty acid chain length, which induce increased textural resilience owing to viscoelasticity (4.0; 5.0). A multidisciplinary approach was able to verify structuring behaviour (4.0; 5.0), using multiple analyses (Wassell et al., 2010b; 2012; Young et al., 2008). Novel structuring solutions in reduced TAG based systems have been provided (4.0; 5.0). This study both enhances current understanding of structuring in low TAG W/O emulsions and has led to novel MAG compositions, which address emulsification, structuring and texture in TAG based food systems (Wassell et al., 2010a; 2012a; 2012b; 2012c; 2012d; 2012e; Bech et al., 2013).

No description available.

Herein two novel synthetic strategies for the synthesis of sub-millimetre sized core–shell particles comprising a polyelectrolyte core and a porous hydrophobic shell are presented. In the first method, a water-in-oil-in-water (W/O/W) double-emulsion was used as a template for the simultaneous polymerisation of both the internal aqueous and the intermediate oil phases, via suspension polymerisation, leading to the formation of a cross-linked poly(acrylic acid-co-bisacrylamide) core contained in a porous poly(4-tert-butylstyrene-co-divinylbenzene) shell. It was found that the formation of core–shell morphology was favoured by the effect of acrylic acid which was responsible for the selective destabilization of the internal aqueous/oil (W/O) interface. It was found that rapid internal phase coarsening promoted the formation of single-core structures. A rapid gel-point of the oil phase, on the other hand, reduced the internal aqueous phase diffusion towards the external phase. The detrimental effect over internal emulsion stability was replicated using ethanol, 2-propanol, n-butanol and propionic acid which were used as a co-solvent in the internal aqueous phase to promote core/shell morphology formation. The second method involved the use of a flow-focusing device for the formation of monodisperse W/O/W emulsion droplets which were photo-polymerised. Anionic poly(sodium acrylate), poly(sodium vinyl sulfonate), and cationic poly(3-acrylamidopropyl)trimethylammonium chloride) hydrogels were encapsulated within a porous poly(trimethylolpropane triacrylate-co-methyl methacrylate) shell. Control over both particle diameter and shell thickness was achieved by tuning the flow rates of the different phases. The use of these novel hydrogel core/shell particles as novel material for environmental applications, including the scavenging of radionuclides, was investigated. It was found that hydrophilic substances including dyes and metal ions were rapidly adsorbed and encapsulated within the core region after diffusing through the permeable porous shell. Part of the results obtained in this work have been published in the article J. Mater. Chem. A, 2013, 1, 12553-12559.

M.Sc. / Emulsions are not widely used in industry for wear-metal-in-oil determinations and this study was undertaken in order to evaluate such a possibility. The use of emulsified standards was compared to aqueous standards for the calibration of an emulsified used lubricating oil sample. The traditionally used methods of ashing in a muffle furnace and dilution with the organic solvent, xylene were also evaluated in comparison with the emulsion methodology. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the wear-metal-in-oil analysis. The performance characteristics of each method were compared for the following metals: AI, Cr, Cu, Fe, Ni, and Pb. The used oil sample and emulsified standards were acid treated and emulsified in water {1% wlw) using tetralin as solvent and triton X-100 as surfactant. This evaluation included the calibration characteristics, precision and accuracy obtained, as well as the results of recovery studies. The emulsification method was found to be comparable to the ashing and dilution methods in terms of calibration and only Cr, Cu, Fe and Pb concentrations were found. The precision of the emulsification method was found, in general, to be close to or less than 2% RSD. The used oil matrix also contained leaked petroleum from a problem car engine. An accurate determination of lead was consequently impossible since the high lead content led to sedimentation. The use of the internal standard, indium, was evaluated for its effectiveness in correcting possible matrix effects that were evident from the results obtained in the recovery studies. The recovery studies showed the Cr and Pb determinations to be adversely affected by internal standardization. An alternative approach for matrix effect correction, the common analyte internal standardization (CAIS) method was also investigated. This method held promise for allowing the use of aqueous standards, instead of oil or emulsion standards, for the calibration of the emulsified oil samples. Three different applications of the CAIS technique were investigated and all proved unsuccessful.

Orientador: Rosiane Lopes da Cunha / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T01:07:13Z (GMT). No. of bitstreams: 1 Costa_AnaLeticiaRodrigues_M.pdf: 3081485 bytes, checksum: 44ad03cd2e14d1ef00c3251b254983eb (MD5) Previous issue date: 2015 / Resumo: A técnica de emulsificação em dispositivos de microfluídica é utilizada para a produção de gotas de diâmetro reduzido e distribuição de tamanho monodispersa. A gelificação da fase dispersa de emulsões água em óleo pode levar à formação de microgéis com elevado potencial para encapsulação de compostos ativos. Do ponto de vista tecnológico, a utilização de partículas de tamanho reduzido permite entrega mais fácil e liberação do bioativo de forma mais eficiente no local alvo. Este trabalho teve como objetivo estudar o processo de formação de microgéis de goma gelana em dispositivos de microfluídica utilizando a técnica de focalização hidrodinâmica. Foram avaliadas as concentrações da goma gelana de 0,5 a 0,7% (m/m) e do agente gelificante acetato de cálcio nas concentrações de 0,5 e 2,0% (m/m) para formação dos microgéis. Na primeira etapa, emulsões simples água em óleo, sendo a fase dispersa constituída de água ou dispersões aquosas de goma gelana e fase contínua constituída por uma mistura composta por óleo de soja e o emulsificante polirricinoleato de poliglicerol (PGPR), foram avaliadas quanto ao regime de formação de gotas em diferentes vazões das fases e razões entre as vazões das fases dispersa e contínua. Também foram determinadas as velocidades reais das fases dentro dos dispositivos de microfluídica e os números adimensionais de Reynolds, Capilar e Weber que descrevem o escoamento dos fluidos no microcanais. Com o controle da condição de processo, vazão de entrada das fases dispersa e contínua, foi possível observar as variações no regime de formação de gotas, que variou desde o gotejamento até o jateamento. Em geral, todas as vazões calculadas (reais) das fases foram menores do que aquelas aplicadas na bomba, sendo este resultado relacionado às limitações das dimensões dos canais e alta viscosidade das fases. Desta forma, os números de Reynolds, Capilar e de Weber calculados a partir das velocidades reais das fases foram menores quando comparados com os valores obtidos usando as velocidades impostas na bomba. Na etapa seguinte, microgéis de goma gelana foram produzidos nos microcanais e caracterizados pela distribuição de tamanho de gotas e microscopia ótica. Os microgéis possuíam formato regular e esférico e distribuição de tamanho altamente monodispersa. O potencial da utilização de microgéis de goma gelana na encapsulação de compostos ativos foi avaliado adicionando o corante hidrofílico Rhodamina B na fase aquosa. As partículas obtidas na saída do dispositivo possuíam coloração vermelha, referente à boa retenção do corante hidrofílico. Desta forma, conclui-se que os microgéis obtidos pela técnica da microfluídica poderão ser utilizados na encapsulação de compostos hidrofílicos, inclusive aqueles sensíveis à temperatura, como as vitaminas e probióticos, na imobilização de proteínas e enzimas, bem como, na entrega de drogas, pois além de apresentarem baixa polidispersidade na distribuição de tamanho das partículas mostraram elevada capacidade de retenção do corante utilizado para simular o composto ativo de interesse / Abstract: Emulsification in microfluidic devices is used for the production of droplets with reduced diameter and monodisperse particle size distribution. Gelation of the disperse phase of water in oil emulsions leads to formation of microgels with high potential for the encapsulation of active compounds. Small particle size allows more efficient release of the bioactive at the target site. This work aimed to study the production of gellan microgel using microfluidic devices through flow- focusing technique. Gellan gum concentration of 0.6% (w/w) and calcium acetate (gelling agent) in concentrations of 0.5 and 2.0% (w/w) were used for the formation of microgels. In the first step, it was evaluated of the droplets formation regime at different flow rates of the phases and flow rate ratio of the dispersed and continuous phases of water-in-oil emulsions, composed by dispersed phase of water or gellan aqueous solutions and continuous phase constituted of a mixture composed of soybean oil and the emulsifier polyglycerol polyricinoleate (PGPR). The real velocity of the phases within the microfluidic devices and dimensionless numbers of Reynols, Capilar and Weber that describe the flow of fluids in microchannels were also evaluated. By controlling the process conditions and the input flow rate of dispersed and continuous phases, variations in the drop formation regime were observed which varied from dripping to the jetting regime, such variation exerted strong influence on droplet size. In general, the real flow rate (calculated values) was lower than those applied by pump, which was related with limitations of the size of channels and high viscosity of the phases. Reynolds, Capilar and Weber numbers calculated from the real velocity were smaller compared with the values obtained using the speed imposed by pump. In the next step, gellan microgels were produced the microchannel and characterized by droplet size distribution and optical microscopy. The microgels exhibit uniform and spherical shape and highly monodisperse distribution size. Potential use as gellan microgels as encapsulating matriz of active compounds was evaluated by adding the hidrophilic dye, Rhodamine B, in the aqueous phase. Results showed a low polydispersity and high hidrophilic compound retention capacity, indicating that microgels obtained by microfluidic technique may be used for the encapsulation of hydrophilic compounds that are sensitive to temperature, such as vitamins, probiotics and immobilization of proteins and enzymes, as well as in drug delivery / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Thermally expandable microspheres are spherical particles around 5-­‐40 µm in size, consisting of a polymeric shell in which a blowing agent has been encapsulated. The microspheres are expanded upon heating, resulting in a particularly low density. Microspheres are therefore suitable to use as light weight filler or as foaming agent. AkzoNobel is world leading in the production of expandable microspheres, which are commercialised under the name Expancel. Sustainability is a great focus at AkzoNobel and two issues that AkzoNobel works with today is to develop products free from chlorine and Me1. The aim with this thesis has been to investigate whether it is possible to produce microspheres free from these chemicals and to see if they can be a more sustainable alternative to one of the existing Expancel grades. In this study, the microspheres have been produced through free radical suspension polymerisation and analysed by measuring mainly the particle size and expansion properties. The polymeric shell was composed of the monomers acrylonitrile, methacrylonitrile, and methyl acrylate. The main focus has been to evaluate the silica-­‐based stabilisation system, which stabilise the monomer droplets during the suspension polymerisation. The stabilisation is possible due to the formation of silica flocs that is adsorbed on the surface of the droplets. It has been investigating how different parameters, e.g. amount of stabiliser or mixing procedure, affects the formation of silica flocs and the stabilisation of monomer droplets. For the silica-­‐based system, it was found that the mixing order, stirring rate, and amount of stabilisers affect the formation of flocs. It was also seen that the amount of stabiliser affect the stabilisation of droplets, and that some stabilisers is more significant than others. Microspheres without chlorine and Me1 have successfully been produced in laboratory scale (50 mL and 1 L). The expansion and size of the microspheres produced in this study was relatively similar to one of the existing Expancel grades. However, the reproducibility of polymerisations in 1 litre reactors has been poor. / Termiskt expanderbara mikrosfärer är sfäriska partiklar, ca 5-­‐40 µm i diameter, som består av ett polymerskal som innesluter en drivgas. Mikrosfärerna expanderar när de utsätts för värme och erhåller då en mycket låg densitet. De är därför lämpliga att använda som fyllmedel då låg vikt är önskvärt eller som skummedel. AkzoNobel är världsledande inom produktion av expanderbara mikrosfärer, som marknadsförs under namnet Expancel. Hållbar utveckling är en viktig fråga för AkzoNobel och två problem som de står inför idag är att utveckla produkter fria från klor och Me1. Målet med detta examensarbete har varit att undersöka om det är möjligt att framställa mikrosfärer fria från dessa kemikalier och om de framtagna mikrosfärerna skulle kunna vare ett hållbarare alternativ till en av de befintliga Expancel-­‐ produkterna. I den här studien har mikrosfärerna framställts genom suspensionspolymerisation som initierats av fria radikaler och de har analyserats främst genom att mäta partikelstorlek och expansionsegenskaper. Polymerskalet bestod av monomererna akrylnitril, metakrylnitril och metylakrylat. I det här arbetet har det viktigaste varit att utvärdera det silikabaserade stabiliseringssystemet som stabiliserar monomerdropparna vid polymerisationen. Stabiliseringen är möjlig eftersom silika bildar flockar som adsorberar på ytan av monomerdropparna. Olika parametrar, exempelvis mängd stabiliseringsmedel och satsningsförfarande, har därför varierats för att undersöka vilken effekt det får på flockningen av silika och stabiliseringen av monomerdroppar. Satsningsordning och omrörningshastiget för stabiliseringssystemet samt mängd stabiliseringsmedel är några av de faktorer som påverkar bildningen av flockar. Det konstaterades även att mängd stabiliseringsmedel påverkar stabiliseringen utav monomerdropparna. Fulländade mikrosfärer utan klor och Me1 har framställts i laboratorieskala (50 mL och 1 L) och partikelstorleken samt expansionsegenskaper är jämförbara med en av Expancels nuvarande produkter. Dock har reproducerbarheten i 1 litersskala varit otillfredsställande.

In this thesis we report the results of investigations on the rheological response of emulsions to the application of the electric field. A front-tracking finite difference scheme is used in conjunction with Taylor-Melcher leaky dielectric theory to study the problem. The numerical results in different regions of the deformation-circulation map show that the structure formation in regions I and III can be hindered by the hydrodynamic effect. This is opposite to what is observed in the perfect dielectric cases and region II of the map. For perfect dielectric systems, where the electrohydrodynamics effects are absent, droplets form chain-like structures spanning the distance between the electrodes after the application of the electric field. Subsequently, the chains interact with each other to form columns comprising two or more chains. Point-dipole approximation is used to analyze the structure formation and it is shown that it is also applicable to region II where the hydrodynamic effect is weak and the behavior of the system is mainly governed by the dielectrophoretic forces. It is shown that the chain formation is not possible in regions I and III due to the competition between the dipolar force and torque on one side and hydrodynamic effect on the other side. In region I, the hydrodynamic torque prevents the chain formation by competing with the dipolar torque, which tends to align the drops with the electric field. On the other hand, in region III, the repulsive nature of the hydrodynamic effect opposes the attractive dipolar force and does not allow the particles to form stable chains.