Luiz Alberto Kanis

Study of poly(ethylene oxide)/Carbopol blends through thermal analysis and infrared spectroscopy

Abstract Properties such as miscibillity, interaction and the thermal degradation behavior of blends of poly(ethylene oxide) (PEO) with Carbopol were studied by thermal analysis (DSC, TGA) and infrared spectroscopy (FTIR). The miscibility of PEO/Carbopol blends in all composition ranges was confirmed, and the interaction is favored by hydrogen bonding between the carboxylic acid group of Carbopol and the PEO ether oxygen. TGA analysis showed that, with temperature increase, anhydride formation occurred first, confirmed by the FTIR bands in 1806, 1756 and 1047xa0cm −1 . Thermal degradation products such as carbon dioxide appear as a result of fragmentation of the anhydride ring structures and decarboxylation of the Carbopol acid groups. Bands related with unsaturated structures (1605xa0cm −1 ) were observed at 310°C and 470°C, presumably as a result of scissions of the main carbon–carbon chain. The activation energy of PEO/Carbopol blends increased with the Carbopol content in the blend, indicating that the thermal degradation is delayed with the presence of Carbopol.

Larvicidal activity of Copaifera sp. (Leguminosae) oleoresin microcapsules against Aedes aegypti (Diptera: Culicidae) larvae.

Studies have demonstrated the potential of Copaifera sp. oleoresin to control Aedes aegypti proliferation. However, the low water solubility is a factor that limits its applicability. Thus, the micro- or nanoencapsulation could be an alternative to allow its use in larval breeding places. The purpose of this study was to evaluate if achievable lethal concentrations could be obtained from Copaifera sp. oleoresin incorporated into polymers (synthetic or natural) and, mainly, if it can be sustained in the residual activity compared to the pure oil when tested against the A. aegypti larvae. Microcapsules were prepared by the process of emulsification/precipitation using the polymers of cellulose acetate (CA) and poly(ethylene-co-methyl acrylate) (PEMA), yielding four types of microcapsules: MicPEMA1 and MicPEMA2, and MicCA1 and MicCA2. When using only Copaifera sp. oleoresin, the larvicidal activity was observed at concentrations of LC50u2009=u200948xa0mg/L and LC99u2009=u2009149xa0mg/L. For MicPEMA1, the LC50 and LC99 were 78 and 389xa0mg/L, respectively. Using MicPEMA2, the LC50 was 120xa0mg/L and LC99 >500xa0mg/L. For microcapsules MicCA1 and MicCA2, the LC50 and LC99 were 42, 164, 140, and 398xa0mg/L, respectively. For a dose of 150xa0mg/L of pure oleoresin, the residual activity remained above 20% for 10xa0days, while the dose of 400xa0mg/L remained above 40% for 21xa0days. The MicPEMA1 microcapsules showed a loss in residual activity up to the first day; however, it remained in activity above 40% for 17xa0days. The microcapsules of MicCA1 showed similar LC50 of pure oil with 150xa0mg/L.

Mechanical properties and total hydroxycinnamic derivative release of starch/glycerol/Melissa officinalis extract films

O objetivo deste trabalho foi estudar as propriedades mecânicas e o mecanismo de liberacao de um sistema topico de liberacao prolongada para o tratamento do Herpes labial a partir de filmes de amido/glicerol/extrato de Melissa officinalis, planta com comprovada atividade antiviral. Foram obtidos quatro filmes polimericos com diferentes concentracoes de amido, glicerol e extrato de Melissa officinalis os quais foram caracterizados mecanicamente e determinado o perfil de liberacao de derivados hidroxicinâmicos. Os resultados demonstraram que o aumento da concentracao de glicerol no filme produz uma reducao no modulo de elasticidade e na tensao de deformacao como consequencia do efeito plastificante. O aumento no volume livre do polimero resultou em aumento da liberacao dos derivados hidroxicinâmicos expressos como acido rosmarinico.

POLY(ETHYLENE-CO-METHYL ACRYLATE)/POLY(CAPROLACTONE) TRIOL BLENDS FOR DRUG DELIVERY SYSTEMS: CHARACTERIZATION AND DRUG RELEASE

Poly(ethylene-co-methyl acrylate) (EMA) and poly (caprolactone) triol (PCL-T) blends, a biodegradable aliphatic polyester with low molecular weight and moderate water solubility containing diltiazem hydrochloride (DZ) were studied in terms of the thermal and morphological properties, and drug release mechanism. An increase in the PCL-T content in the EMA/PCL-T/DZ films decreased the degree of DZ crystallinity. Drug release from these films is temperature-dependent, and it is possible to modify the drug release rate by adjusting the EMA/PCL-T composition of the blends. The mechanism of drug release is governed by PCL-T melting and PCL-T leaching from EMA matrix.

Influência do pH nas propriedades físico-químicas, térmicas e mecânicas de filmes de poli(vinil álcool)/poli(ácido acrílico)/aciclovir

Drug-loaded films represent an alternative method for the treatment of skin lesions caused by Herpes simplex, since they facilitate delivery of the drug directly at the site of lesion. The objective of this work was to prepare PVA/PAA films containing AC at pH 2.0 and 4.0. The results show that the pH of the film preparations influences the polymer¾drug interaction kinetic order and the degree of swelling. The mechanism of release of AC from the films obtained at pH 4.0 was anomalous, whereas for the films prepared at pH 2.0 the release followed zero-order kinetics.