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The twin screw extrusion technique has been explored to produce lyotropic liquid crystal coated powder precursor by exploiting Pluronic F127 thermoreversible gelation property to get powder precursor without granular aggregates or with less compacted granular aggregates. The highly soluble chlorpheniramine maleate loaded in Pluronic F127 solution coated MCC particles prepared through twin screw extrusion was examined to produce the cubic phase (gel) for the development of controlled release formulation and for coating of very fine particles which cannot be achieved by traditional bead coaters. Controlled release formulations are beneficial in reducing the frequency of administration of highly soluble drugs having short half life and also to address the problem of polypharmacy in old age patients by reduction of dosage frequency. An unusual refrigerated temperature (5 C) profile for twin screw extrusion was selected based on the complex viscoelastic flow behaviour of Pluronic F127 solution which was found to be highly temperature sensitive. The Pluronic F127 solution was found to be Newtonian in flow and less viscoelastic at low temperature, such that low temperature (5 C) conditions were found to be suitable for mixing and coating the MCC particles to avoid compacted aggregates. At higher temperatures (35-40 C) Pluronic F127 solution exhibited shear thinning and prominent viscoelasticity, properties which were exploited to force CPM containing Pluronic F127 solution to stick over the MCC surface. This was achieved by elevating the temperature of the last zone of the extrusion barrel. It was found that to avoid compacted aggregates the MCC must be five times the weight of the Pluronic F127 solution and processed at a screw speed of 400 RPM or above at refrigerated temperature. Processing was not found to be smooth at ambient temperature with frictional heat and high torque generation due to significant compaction of coated particles which can be attributed to the elastic behaviour of Pluronic F127 solution at temperatures between ambient to typical body temperature. PLM images confirmed the cubic phase formation (gel) by Pluronic F127 coating which was found to be thick with maximum Pluronic F127 concentration (25%). SEM images showed smoothing of surface topography, and stretching and elongation of MCC fibres after extrusion which is indicative of coating through extrusion processing. Plastic deformation was observed for the lower Pluronic F127 concentration and higher MCC proportions. There was a significant decrease in work done for cohesion by the powder flow analyser observed in the batches with more aggregates compared with batches with least aggregates. A regression analysis study on factorial design batches was conducted to investigate the significant independent variables and their impact on dependent variables for example % torque, geometric mean diameter and work done for cohesion, and to quantitatively evaluate them. From the regression analysis data it was found that the coefficient of determination for all three dependent variables was in the range of 55-62%. The pharmaceutical performance of the prepared coated LLC precursor through twin screw extrusion in terms of controlled release was found to be very disappointing. Almost 100% chlorpheniramine maleate was released within 10-15mins, defined as providing burst release. The MDSC method was developed within this work to detect Pluronic F127 solution cubic phase formation. The MDSC method was developed to consider sample size, effect of heating and cooling, sample heat capacity, and the parameters for highest sensitivity which can be followed by sample accurately without the phase lag to produce accurate repeatable results.

Resumo: A doença de Alzheimer (DA) é uma doença altamente incidente na população mundial, acometendo cerca de 40 milhões de pessoas com idade igual ou superior a 65 anos, levando à perda da memória e cognição. A via nasal é uma via alternativa que pode promover a rápida absorção do fármaco, além de poder direcionar fármacos para o cérebro, e evitar o metabolismo pré-sistêmico. Porém, ela possui mecanismos de depuração mucociliar que podem eliminar rapidamente a formulação da cavidade nasal. Os sistemas nanoestruturados baseados em tensoativos (SNBT) que sofrem geleificação in situ demonstram ser uma opção interessante para viabilizar a administração de fármacos por esta via. O trans-resveratrol (RES) tem apresentado atividade no tratamento da DA, atuando sobre vias moleculares específicas, como a capacidade da inibição da formação da placa beta-amiloide (Aβ), despolimerização da placa Aβ formada durante a doença e atuando sobre o sistema colinérgico, inibindo a acetilcolinesterase e diminuindo a neuroinflamação e formação de radicais livres no cérebro. Entretanto, seu uso é limitado devido à sua insolubilidade em meio aquoso. Desta forma, a solubilização do RES em SNBT pode ser uma opção interessante para viabilizar o seu uso. O objetivo deste trabalho foi desenvolver e caracterizar sistemas precursores de cristais líquidos compostos pelos tensoativos álcool cetílico etoxilado 20 OE e propoxilado 5 OP (PPG-5-CETETH-20), ácido oleílico 20 OE (OLETH-20), ácido oleílico 3 OE (OLETH-3) e... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Alzheimer's disease (AD) is a highly incident illness in the world population, it affects about 40 million people aged 65 or over, and this pathology leads to memory and cognition loss. The nasal route is an alternative that can promote the rapid absorption of the drugs, besides to target drugs to the brain and to avoid the pre-systemic metabolism. However, it has mucociliary clearance that can rapidly eliminate the formulation existing under the nasal cavity. The surfactant-based nanostructured systems (SBNS) undergoes in situ gelling and seems to be an interesting feasible option for use by intranasal route. Trans-resveratrol (RES) has properties for the AD treatment, it acts on specific molecular pathways, such as the ability to inhibit the formation of amyloid-beta (Aβ) plaques, depolymerization of Aβ plaques developed during the progressing of disease and acting on the cholinergic system, inhibiting an acetylcholinesterase, and decreasing neuroinflammation and formation of free radicals in the brain. However, its use is limited due to insolubility in aqueous medium, however RES can be solubilized in these systems and therefore it can be an interesting option to do its viable employ. The aim of this work was to develop and characterize liquid crystal precursor systems composed of polyoxypropylene (5) polyoxyethylene (20) cetyl alcohol (PPG-5-CETETH-20), polyoxyethylene (20) oleyl alcohol (OLETH-20), polyoxyethylene (3) oleyl alcohol (OLETH- 3) and sorbitan polysorbate (PS... (Complete abstract click electronic access below) / Doutor

Misturas liotrópicas de laurato de potássio (KL)/ sulfato de potássio (K2SO4)/ álcool (CnH2n+1OH)/ água (H2O) apresentam fases no estado líquido cristalino nemático. Essas fases nemáticas foram colesterizadas através da adicão do agente quiral brucina à mistura. Este estudo foi realizado mantendo as frações molares de todos os constituintes das misturas constantes e variando o comprimento da mol´ecula de álcool entre oito (1-octanol) e dezesseis (1-hexadecanol) átomos de carbono. Três fases colestéricas foram identificadas: ChD (colestérica discótica), ChB (colestérica biaxial) e ChC (colestérica calamítica). O diagrama de fases foi construído em função do número de átomos de carbono n na molécula do álcool. As transições entre as fases colestéricas foram investigadas por medições das birrenfringências ópticas usando microscopia óptica de luz polarizada. As misturas com 9 n 12 apresentaram as três fases colestéricas como função da temperatura e uma região de crossover entre as fases ChD e ChB, com comprimento de correlação a temperatura nula maior do que as dimensões micelares típicas. Misturas com n=8 e n=13 apresentaram transição de fase de primeira ordem entre as fases ChD e ChC, sem a presença da fase ChB intermediária a elas. As misturas com n=14, 15 e 16 apresentaram somente a fase ChC como função da temperatura. Os resultados foram interpretados como consequência da nanosegregação das moléculas de álcool nas micelas com relação às moléculas do anfifílico principal. / Lyotropic mixtures of potassium laurate (KL)/ potassium sulphate (K2SO4)/ alcohol (CnH2n+1OH)/ water (H2O) present nematic liquid crystal phases. These nematic phases were cholesterized by the doping of the mixtures with the chiral agent brucine. This study was conducted by keeping constant the molar fractions of all constituents of the mixtures and varying the length of the alcohol molecule between eight (1-octanol) and sixteen (1-hexadecanol) carbon atoms. Three cholesteric phases were identified: ChD (discotic cholesteric), ChB (biaxial cholesteric), and ChC (calamitic cholesteric). The phase diagram was constructed as a function of the number of carbon atoms n in the alcohol molecule. The cholesteric-cholesteric phase transitions were investigated by measurements of the optical birefringences via polarized light microscopy. The mixtures with 9 n 12 presented the three cholesteric phases as a function of temperature and a crossover between the ChD and ChB phases, with a bare correlation length larger than the typical micellar dimensions. Mixtures with n =8 and n =13 exhibited first order phase transitions among the ChD and the ChC phases, without the presence of the intermediate ChB phase. Mixtures with n =14, 15 and 16 showed only the ChC phase as a function of temperature. These results were interpreted as a consequence of the nanosegregation of the alcohol molecules in the micelles with respect to the main amphiphilic molecules.

Com uma mistura de laurato de potássio, decanol e agua, determina-se a birrefringência induzida, na fase isotrópica, por gradientes de velocidade, no interior da amostra. Os movimentos são provocados através de vibrações periódicas nas paredes do porta amostras. O tempo de relaxação, da estrutura de rolos, e determinado experimental e teoricamente. É determinado, também, o parâmetro T AST (temperatura em torno da temperatura de transição), ate então desconhecido, em cristais líquidos liotrópicos. Como uma provável aplicação pratica, e proposta a confecção de dispositivos sensíveis a vibrações. / With a mixture of the Potassium Laurate, Decanol and water, the birefringence induced by gradient of the velocity, in the isotropic phase, is determinated. The movement are provocated through periodic vibrations of the superface of the sample holder. The relaxation time of the roll structure is determinated experimental an theorically. The temperature T* (temperature around the transition temperature), well-known in thermotropic liquid crystals, is determinated in liotropic liquid crystals. The confection of the sensible vibration dispositive is proposed.

Estruturas líquidas cristalinas estão presentes em materiais compostos por moléculas com anisotropia de forma e são caracterizadas por uma ordem orientacional de longo alcance. Na mesofase nemática as moléculas alongadas tendem a se alinhar paralelas entre si, a direção média de orientação define é caracterizada por um vetor unitário, chamado de diretor n. Os cristais líquidos liotrópicos são obtidos usualmente a partir da dispersão de moléculas anfílicas em água. Essas moléculas anfílicas, por terem uma parte polar e uma parte apolar, tendem a formar agregados anisotrópicos, com a parte polar da molécula na superfície. Esse tipo de estrutura esta presente em todos os seres vivos e o exemplo mais clássico é a membrana da célula. A existência de uma superfície de contorno ou uma fronteira modifica as propriedades de um material na vizinhança dessa fronteira. Isso é particularmente verdadeiro para os cristais líquidos, que são muitos sensíveis as condições de contorno, mesmos quando estas não são tão intensas. De fato essa propriedade e bastante útil para a fabricação de dispositivos eletro-ó pticos. Um dos efeitos de superfície mais evidente é a mudança no ordenamento das moléculas devido a quebra de simetria na superfície. Nas fases nemáticas esse efeito microscópico resulta na formação de uma camada superficial com uma ordem posicional que se estende ao longo de uma certa distância no volume. 0 outro efeito resulta da origem a mudanças significativas no estado orientacional das moléculas no volume devido a presença de forças superficiais. Esse efeito é conhecido como ancoramento. Na ausência de campos extemos ou condições de contorno qualquer orientação é igualmente provável. Neste trabalho serão apresentados os resultados de investigação das propriedades de cristais líquidos liotrópicos na interface com um substrata. Estudamos o comportamento dinâmico da camada superficial quando o campo magnético é aplicado e induz uma re­ orientação do diretor. Nesse estudo são utilizadas amostras de cristal líquidos liotrópicos. / Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are usually obtained by the dispersion of amphiphilic molecules in water. Due the fact that these molecules present a polar head and a non-polar tail, they tend to form aggregates with the polar part at the aggregate surface. This type of struc­ ture is present in all living being; the most classical example is the cell membrane. The existence of a boundary surface affects the properties of a material close to this boundary. This particularly true for liquid crystals, which are very sensitive to boundary conditions, even when weak. Indeed, this property is quite useful in the fabrication of electro-optic devices. One of the most obvious surface effect is the change in the molecules organization due to a breaking of the symmetry at the boundary surface. In the nematic phases, this microscopic effect results in the formation of a surface la yer with a positional order that extends through the bulk up to a certain distance from the surface. The other effect of the surface results in a change in the orientational state of the molecules in the volume due to the sur face forces. This macroscopic effect is known as anchoring. In the absence of any external field or boundary conditions, all molecular orientation is equally probable. In this work, we will present some results of the investigation of the properties of lyotropic liquid crystals at the interface with a solid substrate. We have studied the dy­ namic of the surface layer when a applied magnetic field induces a reorientation of the nematic director. In this study different systems were used: lyotropic liquid crystals in the nematic phase, ferronematics (nematic phase doped with ferrofluid) and filled nematics (nematic phase doped with silica nano-spheres). By means of transmittance measurements.

Com uma mistura de laurato de potássio, decanol e agua, determina-se a birrefringência induzida, na fase isotrópica, por gradientes de velocidade, no interior da amostra. Os movimentos são provocados através de vibrações periódicas nas paredes do porta amostras. O tempo de relaxação, da estrutura de rolos, e determinado experimental e teoricamente. É determinado, também, o parâmetro T AST (temperatura em torno da temperatura de transição), ate então desconhecido, em cristais líquidos liotrópicos. Como uma provável aplicação pratica, e proposta a confecção de dispositivos sensíveis a vibrações. / With a mixture of the Potassium Laurate, Decanol and water, the birefringence induced by gradient of the velocity, in the isotropic phase, is determinated. The movement are provocated through periodic vibrations of the superface of the sample holder. The relaxation time of the roll structure is determinated experimental an theorically. The temperature T* (temperature around the transition temperature), well-known in thermotropic liquid crystals, is determinated in liotropic liquid crystals. The confection of the sensible vibration dispositive is proposed.

Several analytical mean field models are presented for the class of stimuli responsive polymers that are driven by the lower critical solution temperature (LCST) transition. For solutions above the polymer crossover concentration, a hybrid model combines lattice-fluid excluded volume and van-der-Waals interactions with a combinatorial approach for the statistics of hydrogen bonding, hydration, and ionic bonding. This approach yields models for the LCST of both neutral polymers and lightly charged polyelectrolytes in aqueous salt solution. The results are shown to be in semi-quantitative agreement with experimental data for the cloud point of polyethylene oxide (PEO) in aqueous solution with various salts, and some aspects of the lyotropic series are reproduced. Results for lightly charged polyelectrolytes are compared to and shown to be in qualitative agreement with aspects of experimentally observed behavior. Finally, a framework is established for extension of these models to further aspects of the lyotropic series and polyelectrolyte behavior. At the nanoscale, lattice fluid (LF) and scaled particle theory (SPT) approaches are employed to model the LCST-related coil-globule-transition (CGT) of isolated polymer chains in highly dilute solution. The predicted CGT behavior semi-quantitatively correlates with experimental results for several polymer-solvent systems and over a range of pressures. Both the LF and SPT models exhibit a heating induced coil-to-globule transition (HCGT) temperature that increases with pressure until it merges with a cooling induced coil-to-globule transition (CCGT). The point at which the CCGT and HCGT meet is a hypercritical point that also corresponds to a merging of the lower critical and upper critical solution temperatures. Theoretical results are discussed in terms of a generalized polymer/solvent phase diagram that possesses three hypercritical points. Within the lattice model, a dimensionless transition temperature [author gives mathematical symbol] is given for a long chain simply by the equation [author gives mathematical equation], where [part of the equation] is the bulk solvent occupied volume fraction at the transition temperature. Furthermore, there is a critical value of the ratio of polymer to solvent S-L characteristic temperature below which no HCGT transition is predicted for an infinite chain. / text

Estruturas líquidas cristalinas estão presentes em materiais compostos por moléculas com anisotropia de forma e são caracterizadas por uma ordem orientacional de longo alcance. Na mesofase nemática as moléculas alongadas tendem a se alinhar paralelas entre si, a direção média de orientação define é caracterizada por um vetor unitário, chamado de diretor n. Os cristais líquidos liotrópicos são obtidos usualmente a partir da dispersão de moléculas anfílicas em água. Essas moléculas anfílicas, por terem uma parte polar e uma parte apolar, tendem a formar agregados anisotrópicos, com a parte polar da molécula na superfície. Esse tipo de estrutura esta presente em todos os seres vivos e o exemplo mais clássico é a membrana da célula. A existência de uma superfície de contorno ou uma fronteira modifica as propriedades de um material na vizinhança dessa fronteira. Isso é particularmente verdadeiro para os cristais líquidos, que são muitos sensíveis as condições de contorno, mesmos quando estas não são tão intensas. De fato essa propriedade e bastante útil para a fabricação de dispositivos eletro-ó pticos. Um dos efeitos de superfície mais evidente é a mudança no ordenamento das moléculas devido a quebra de simetria na superfície. Nas fases nemáticas esse efeito microscópico resulta na formação de uma camada superficial com uma ordem posicional que se estende ao longo de uma certa distância no volume. 0 outro efeito resulta da origem a mudanças significativas no estado orientacional das moléculas no volume devido a presença de forças superficiais. Esse efeito é conhecido como ancoramento. Na ausência de campos extemos ou condições de contorno qualquer orientação é igualmente provável. Neste trabalho serão apresentados os resultados de investigação das propriedades de cristais líquidos liotrópicos na interface com um substrata. Estudamos o comportamento dinâmico da camada superficial quando o campo magnético é aplicado e induz uma re­ orientação do diretor. Nesse estudo são utilizadas amostras de cristal líquidos liotrópicos. / Liquid crystalline structures are found in materials made from molecules which are anisotropic in shape; such material are characterized mainly by a long range orientational order. In the nematic phase, the rodlike molecules tend to align parallel to each other. The average orientation defines a unit vector, called director n. Lyotropic liquid crystals are usually obtained by the dispersion of amphiphilic molecules in water. Due the fact that these molecules present a polar head and a non-polar tail, they tend to form aggregates with the polar part at the aggregate surface. This type of struc­ ture is present in all living being; the most classical example is the cell membrane. The existence of a boundary surface affects the properties of a material close to this boundary. This particularly true for liquid crystals, which are very sensitive to boundary conditions, even when weak. Indeed, this property is quite useful in the fabrication of electro-optic devices. One of the most obvious surface effect is the change in the molecules organization due to a breaking of the symmetry at the boundary surface. In the nematic phases, this microscopic effect results in the formation of a surface la yer with a positional order that extends through the bulk up to a certain distance from the surface. The other effect of the surface results in a change in the orientational state of the molecules in the volume due to the sur face forces. This macroscopic effect is known as anchoring. In the absence of any external field or boundary conditions, all molecular orientation is equally probable. In this work, we will present some results of the investigation of the properties of lyotropic liquid crystals at the interface with a solid substrate. We have studied the dy­ namic of the surface layer when a applied magnetic field induces a reorientation of the nematic director. In this study different systems were used: lyotropic liquid crystals in the nematic phase, ferronematics (nematic phase doped with ferrofluid) and filled nematics (nematic phase doped with silica nano-spheres). By means of transmittance measurements.

Misturas liotrópicas de laurato de potássio (KL)/ sulfato de potássio (K2SO4)/ álcool (CnH2n+1OH)/ água (H2O) apresentam fases no estado líquido cristalino nemático. Essas fases nemáticas foram colesterizadas através da adicão do agente quiral brucina à mistura. Este estudo foi realizado mantendo as frações molares de todos os constituintes das misturas constantes e variando o comprimento da mol´ecula de álcool entre oito (1-octanol) e dezesseis (1-hexadecanol) átomos de carbono. Três fases colestéricas foram identificadas: ChD (colestérica discótica), ChB (colestérica biaxial) e ChC (colestérica calamítica). O diagrama de fases foi construído em função do número de átomos de carbono n na molécula do álcool. As transições entre as fases colestéricas foram investigadas por medições das birrenfringências ópticas usando microscopia óptica de luz polarizada. As misturas com 9 n 12 apresentaram as três fases colestéricas como função da temperatura e uma região de crossover entre as fases ChD e ChB, com comprimento de correlação a temperatura nula maior do que as dimensões micelares típicas. Misturas com n=8 e n=13 apresentaram transição de fase de primeira ordem entre as fases ChD e ChC, sem a presença da fase ChB intermediária a elas. As misturas com n=14, 15 e 16 apresentaram somente a fase ChC como função da temperatura. Os resultados foram interpretados como consequência da nanosegregação das moléculas de álcool nas micelas com relação às moléculas do anfifílico principal. / Lyotropic mixtures of potassium laurate (KL)/ potassium sulphate (K2SO4)/ alcohol (CnH2n+1OH)/ water (H2O) present nematic liquid crystal phases. These nematic phases were cholesterized by the doping of the mixtures with the chiral agent brucine. This study was conducted by keeping constant the molar fractions of all constituents of the mixtures and varying the length of the alcohol molecule between eight (1-octanol) and sixteen (1-hexadecanol) carbon atoms. Three cholesteric phases were identified: ChD (discotic cholesteric), ChB (biaxial cholesteric), and ChC (calamitic cholesteric). The phase diagram was constructed as a function of the number of carbon atoms n in the alcohol molecule. The cholesteric-cholesteric phase transitions were investigated by measurements of the optical birefringences via polarized light microscopy. The mixtures with 9 n 12 presented the three cholesteric phases as a function of temperature and a crossover between the ChD and ChB phases, with a bare correlation length larger than the typical micellar dimensions. Mixtures with n =8 and n =13 exhibited first order phase transitions among the ChD and the ChC phases, without the presence of the intermediate ChB phase. Mixtures with n =14, 15 and 16 showed only the ChC phase as a function of temperature. These results were interpreted as a consequence of the nanosegregation of the alcohol molecules in the micelles with respect to the main amphiphilic molecules.