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Daniella Lury Morgado,Odilio Benedito Garrido Assis 한국고분자학회 2016 Macromolecular Research Vol.24 No.11
In this study the production of biodegradable nanofibrous structures of poly(lactic acid) (PLA) blended with the water-soluble salt trimethylchitosan (TMC) was investigated by using the electrospinning process. Different concentrations of PLA (8 and 10% w/v) and TMC (0.5, 1, and 2% w/v) were prepared and spun. The morphology, diameter and structure of PLA/TMC blended nanofibers were characterized by scanning electron microscope (SEM), atomic force microscope (AFM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC) and contact angle measurements. Images obtained from SEM showed that the blended nanofibers display a uniform and smooth morphology without bead formation. The diameters of the fibers were affected by the presence of chitosan derivative, decreasing from 264 to 184 nm when the TMC addition was 20% (w/w). FTIR and XRD results indicate strong intermolecular hydrogen bonds between the molecules of PLA and chitosan derivative, with reduction in the crystallinity, thermal stability and hydrophobicity as TMC content increases in the blend.
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Cashew Gum-Chitosan Blended Films: Spectral, Mechanical and Surface Wetting Evaluations
Carla Silva Martins,Daniella Lury Morgado,Odilio Benedito Garrido Assis 한국고분자학회 2016 Macromolecular Research Vol.24 No.8
Blends of cashew tree gum with chitosan and glycerol as plasticizer were prepared by casting and characterized by Fourier transform infrared spectroscopy (FTIR), mechanical (DMA) and thermogravimetric analysis (TG), scanning electron microscopy (SEM) and surface wettability by static contact angle measurements. FTIR analysis confirmed the consolidation of both polysaccharides and revealed a clearly interaction between the glycerol molecules and hydroxyl groups of chitosan. Chitosan and glycerol improved films mechanical properties and interferes on surface wettability. The unblended cashew gum films presented hydrophilic surfaces (medium measure angle as 40o) and with the addition of chitosan provides a shift towards a more hydrophobic behavior (52o and 75o for additions of 0.5% and 1.0% (w/w) chitosan respectively). Microscopy surface observation confirmed that the presence of glycerol reduced film cracking, changing them from fragile to a more plastic property. The film forming ability of chitosan is also preserved when blending with cashew gum.
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Douglas de Britto,Marcia R. de Moura,Fauze A. Aouada,Flávia G. Pinola,Lícia M. Lundstedt,Odilio B. G. Assis,Luiz H. C. Mattoso 한국고분자학회 2014 Macromolecular Research Vol.22 No.12
Nanoencapsulation is a process suitable for use in reducing degradation of instable components. In thisstudy, chitosan and trimethyl chitosan with tripolyphosphate were used to nanoencapsulate vitamins C, B9, and B12. Analysis of the particle size showed that for a fix proportion of the polymer tripolyphosphate, the system showed awide variation in size with the amount of added vitamins: e.g., for vitamin B9, the particle size varied from 150±5nm to 809±150 nm. The zeta potential confirmed that trimethyl chitosan nanoparticles generally had a lower net positivecharge (20 mV) than chitosan nanoparticles (40 mV). The encapsulation efficiency was found to be dependenton nanoparticle structure and vitamin solubility, with vitamin B9 the most efficiently encapsulated (approximately40%). UV-Visible spectroscopy indicated different release profiles for vitamins C, B9, and B12 in a neutral PBSsolution with release rates of 36%, 52%, and 16% after 2, 24, and 4 h, respectively. In conclusion the liberation wasfound to be slower in acidic media.
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