Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2015-12-02T22:22:38Z No. of bitstreams: 1 RobertaTalitaStopilha_DISSERT.pdf: 9026948 bytes, checksum: 15e7a4c81ad84759d46e4d3ed6775c19 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2015-12-09T19:28:21Z (GMT) No. of bitstreams: 1 RobertaTalitaStopilha_DISSERT.pdf: 9026948 bytes, checksum: 15e7a4c81ad84759d46e4d3ed6775c19 (MD5) / Made available in DSpace on 2015-12-09T19:28:21Z (GMT). No. of bitstreams: 1 RobertaTalitaStopilha_DISSERT.pdf: 9026948 bytes, checksum: 15e7a4c81ad84759d46e4d3ed6775c19 (MD5) Previous issue date: 2014-09-05 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Os complexos polieletrol?ticos nanoparticulados foram obtidos usando quitosana e poli(metacrilato de s?dio). A forma??o dos complexos foi avaliada por turbidimetria, condutometria, viscosimetria e espalhamento din?mico da luz. A presen?a de excesso de cargas positivas pode ser evidenciada atrav?s da an?lise do potencial zeta. O di?metro das part?culas foi caracterizado pela t?cnica de espalhamento din?mico da luz e a morfologia por microscopia de for?a at?mica. Em todos os experimentos uma mudan?a abrupta de comportamento foi evidenciada no intervalo de raz?o molar (grupos carboxilato/amino) entre 0,7-0,8. Essas mudan?as de comportamento puderam ser relacionadas com uma proposta de mecanismo de forma??o dos complexos polieletrol?ticos, baseada na redu??o das dimens?es macromoleculares dos aglomerados de complexos polieletrol?ticos sol?veis seguidos de segrega??o de fase. / Polyelectrolyte complexes (PECs) nanoparticles were prepared using chitosan and sodium polymethacrylate. The complex formation was investigated using turbidimetry, conductometry, viscometry, and dynamic light scattering. The presence of excess positive charges was evidenced by zeta potential measurements. The particle diameter was characterized by dynamic light scattering and the morphology by atomic force microscopy. In all experiments an abrupt change in behavior was observed at a carboxyl:amino molar ratio around 0.7?0.8. Those changes in behavior were related to a proposed mechanism of complex formation based on the decrease of macromolecular dimensions of soluble polyelectrolyte complex clusters, followed by phase segregation

Made available in DSpace on 2014-12-17T15:42:27Z (GMT). No. of bitstreams: 1 MariaSPL.pdf: 2188057 bytes, checksum: 3142bea2af0c353bf960b7b878efd707 (MD5) Previous issue date: 2006-11-17 / The aim of this study was to generate an asymmetric biocompactible and biodegradable chitosan membrane modified by the contact with a poly(acrylic acid) solution at one of its sides at room temperature and 60◦C. The pure chitosan membrane, as well as the ones treated with poly(acrylic acid) were characterized by infrared spectroscopy (FTIRATR) at angles of 39◦, 45◦ and 60◦ , swelling capacity in water, thermal analysis (TG/DTG), scanning electronic microscopy (SEM) and permeation experiments using metronidazole at 0,1% and 0,2% as a model drug. The results confirmed the presence of ionic interaction between chitosan and poly(acrylic acid) by means of a polyelectrolyte complex (PEC) formation. They also showed that such interactions were more effective at 60◦C since this temperature is above the chitosan glass transition temperature wich makes the diffusion of poly(acrylic acid) easier, and that the two treated membranes were asymmetrics, more thermically stable and less permeable in relation to metronidazole than the pure chitosan membrane / O prop?sito deste estudo foi produzir uma membrana assim?trica biocompat?vel e biodegrad?vel de quitosana modificada pelo contato com uma solu??o de poli(?cido acr?lico) em uma de suas superf?cies ? temperatura ambiente e a 60◦C. As membranas de quitosana pura, quitosana com poli(?cido acr?lico) a 25◦C e quitosana com poli(?cido acr?lico) a 60◦C foram caracterizadas por: espectroscopia no infravermelho (FTIRATR) em ?ngulos de incid?ncia de 39◦, 45◦ e 60◦, ganho de massa em ?gua, an?lise t?rmica (TG/ DTG), microscopia eletr?nica de varredura (MEV) e, ainda, atrav?s dos ensaios de permea??o in vitro utilizando como f?rmaco modelo o metronidazol em solu??o aquosa nas concentra??es de 0,1 e 0,2%. Os resultados obtidos comprovaram a exist?ncia de intera??es i?nicas entre os dois pol?meros, atrav?s da forma??o dos chamados complexos polieletrol?ticos. Tamb?m mostraram que a reticula??o foi mais efetiva a 60◦C , uma vez que essa temperatura est? acima da temperatura de transi??o v?trea da quitosana, o que facilita a difus?o do poli(?cido acr?lico) e que as membranas resultantes s?o assim?tricas, mais est?veis termicamente e menos perme?veis ao metronidazol do que a membrana de quitosana pura

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-05-30T22:35:17Z No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-06-01T21:32:38Z (GMT) No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) / Made available in DSpace on 2016-06-01T21:32:38Z (GMT). No. of bitstreams: 1 WildsonArcanjoDeMorais_TESE.pdf: 7950168 bytes, checksum: 6a3da8d5da57db90a9fa474b79780a53 (MD5) Previous issue date: 2015-08-18 / A ind?stria de petr?leo necessita de v?rias subst?ncias qu?micas em seus processos de extra??o e investe em novas tecnologias a todo o momento. Os sistemas micelares do tipo-minhoca-WLM e os complexos polieletrol?ticos-PECs est?o sendo estudados para ingressar como novas tecnologias na extra??o de ?leo. Esta tese objetiva obter, caracterizar e identificar esses sistemas coloidais utilizando t?cnicas de espalhamento de luz como principais ferramentas; possibilitando o conhecimento de base para poss?veis aplica??es na ind?stria petrol?fera. Os par?metros obtidos no DLS, b, GC e n sofreram transi??es na concentra??o tensoativo/co-tensoativo 200g/L. A adi??o da fase ?leo, xileno, dificulta a transi??o de micelas esf?ricas para micelas minhoca. No SAXS, a rela??o RG,O/ RG,S atinge um m?ximo que corrobora com a transi??o no DLS. b aumenta bruscamente, n se torna mais homog?neo, GC,2 e a contribui??o para o segundo processo, f2, foram visualizados para raz?es poli?nion/polic?tion WAC pr?ximas de 2. Essa regi?o, no SAXS, aglomerados de PECs se adsorvem nas part?culas prim?rias, que contribuiu para o comportamento dos gr?ficos de Kratky. As fun??es P(r) perdem seu formato ?sino? e se alargam. As contribui??es de ?rea S17 e S29 foram maiores para menores valores de WAC e S37 foi influente em valores maiores. / The oil industry needs various chemicals compounds in their extraction processes and invests in new technologies all the time. Worm-like micelles-WLM and polyelectrolyte complexes-PECs have been studied to join as new technologias in oil extraction processes. This thesis aims to obtain, characterize and identify these colloidal systems using as a tool light scattering experiments; enabling the required knowledge to applied them in oil industry. To the surfactants systems, the parameters from DLS, b, GC and n in a function of surfactant/co-surfactant concentrations suffered transitions around 200 g/L. The addition of oil phase, xylene, hinders the transition from spherical micelles to worm-like micelles. In SAXS, the ratio RG,O/ RG,S reaches a maximum value which corroborates with the transition in DLS. To PECs, b increases sharply, n becomes more homogeneous, GC,2 and second contribution to the process, f2, were visualized for polyanion/polycation ratio with WAC next 2. This region in SAXS, PECs clusters adsorb in primary particles, which contributed to the behavior of Kratky graphics. The pair distribution functin, P(r), lose its bell shape and widen. The S17 and S29 were higher for lower values of WAC ratio. S37 was influential in higher values.