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Previous issue date: 2016-07-22 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Dispers?es de complexos polieletrol?ticos (PEC) foram preparadas a partir de quitosana e
poli(metacrilato de s?dio), atrav?s da mistura de suas solu??es, a diferentes raz?es molares
carboxila/amino, rCA. O raio de giro foi determinado por SAXS e revelou que na medida que
rCA aumentava as dimens?es das PEC?s decresciam, atingindo um m?nimo a rCA = 0.75, a qual
foi considerada a raz?o na qual as dimens?es dos agregados eram m?nimas, sendo seguido de
colapso e crescimento de part?culas maiores. Distribui??es de dist?ncia entre pares, P(r),
tornaram-se mais estreitas at? rCA = 0.75, aumentando suas larguras a partir deste ponto.
Par?metros relacionados ? relaxa??o, retirados de fun??es de correla??o de intensidade (ICF)
de DLS identificaram tr?s processos principais de relaxa??o. O processo mais r?pido,
relacionado a movimentos aleat?rios de mol?culas de polieletr?lito livres desapareceu, na
medida em que rCA aumentou. Os outros dois processos de relaxa??o foram fun??es de rCA e
apresentaram mudan?as caracter?sticas a rCA = 0.75. No mesmo valor de rCA, a energia de
ativa??o para a taxa de relaxa??o m?dia indicou a ocorr?ncia de uma clara mudan?a na
natureza das intera??es nas estruturas de PEC. O di?metro hidrodin?mico, determinado por
DLS, foi muito maior que o raio de giro, determinado por SAXS. Part?culas de PEC podem
ser descritas, consequentemente, como composta por um caro?o s?lido, rico em material
segregado, insol?vel, envelopado por aglomerados sol?veis de PEC, possivelmente na forma
de g?is altamente hidratados. / Polyelectrolyte complex (PEC) dispersions were prepared from chitosan and poly(sodium
acrylate), NaPMA, by mixing their solutions., at different carboxyl to aminium molar ratio,
rCA. Gyration radius was determined by SAXS and showed that, as rCA increased, PEC
dimensions decreased and reached a minimum at rCA = 0.75, which was considered the ratio at
which PEC cluster dimensions was minimum, following collapse and growth of larger
particles. Pair distance distributions, P(r), became narrower up to rCA = 0.75, increasing its
width from this point. Relaxation-related parameters from DLS intensity correlation functions
(ICF) identified three main relaxation process. The fast process, related to free polyelectrolyte
molecules random motion disappeared as rCA was increased. The other two relaxation process
were a function of rCA and presented marked changes at rCA = 0.75. At the same value of rCA
the energy of activation for the average relaxation rate showed the occurrence of a clear
change in the nature of PEC-related interactions. As hydrodynamic diameter, determined by
DLS was much larger than the gyration radius determined by SAXS, PEC particles could be
described as being composed by a core, rich in segregated, insoluble material, enveloped by
PEC soluble clusters, possibly in the form of water-rich gels.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21675 |
| Date | 22 July 2016 |
| Creators | Souza, Paulo Reniere Silva de |
| Contributors | 90623207753, Wanderley Neto, Alcides de Oliveira, 00738841463, Lucas, Elizabete Fernandes, 78981948704, Menezes, Fabricio Gava, 03114939988, Fonseca, Jos? Luis Cardozo |
| Publisher | PROGRAMA DE P?S-GRADUA??O EM QU?MICA, UFRN, Brasil |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Source | reponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN |
| Rights | info:eu-repo/semantics/openAccess |
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