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- ItemAcesso aberto (Open Access)Physical-chemical properties of nanocomposites based on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and titanium dioxide nanoparticles(Iop Publishing Ltd, 2018) Braga, Natalia F. [UNIFESP]; da Silva, Ana Paula [UNIFESP]; Arantes, Tatiane Moraes; Lemes, Ana Paula [UNIFESP]; Cristovan, Fernando Henrique [UNIFESP]Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was reinforced with titanium dioxide (TiO2) in concentrations of 1.0%, 2.5% and 5.0% (m/m) to produce nanocomposites by the solvent casting technique. TiO2 was synthesized by a hydrothermal treatment to produce nanoparticles. The nanostructure of the nanoparticles was studied by x-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The XRD confirmed TiO2 crystalline nanoparticles, with a mixture of anatase and rutile phases. Through TEM analysis, the formation of TiO2 nanorod agglomerates with an average diameter and length of 40 and 12 nm, respectively, was observed. The thermal and mechanical properties of the pure PHBV and nanocomposite films were characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis. The DSC analysis showed that the glass transition temperature decreased with the inclusion of TiO2 in the PHBV matrix in relation to pure PHBV. The results of biodegradation assays for the PHBV and nanocomposites in an aqueous medium and in soil showed morphological and structural changes for all samples, indicating a high biodegradation rate for this material. The most important conclusion is that the biodegradation of the PHBV was not affected by the addition of nanoparticles, thus enabling the use of nanocomposites in applications requiring biodegradable materials.
- ItemAcesso aberto (Open Access)Preparação e caracterização de nanocompósitos estruturais baseados em poli(3-hidroxibutirato-co-hidroxivalerato) e nanopartículas de dióxido de titânio para o emprego em engenharia tecidual(Universidade Federal de São Paulo (UNIFESP), 2015-10-30) Braga, Natalia Ferreira [UNIFESP]; Cristovan, Fernando Henrique [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Preparation and characterization of structural nanocomposites based on poly (3-hydroxybutyrate-co-hydroxyvalerate) and titanium dioxide nanoparticles for use in tissue engineering In this work it was developed nanocomposites based on poly (3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) and titanium dioxide (TiO2), by means of three different techniques: casting, electrospinning, and spin-coating. Therefore, the TiO2 nanoparticles were synthesized by hydrothermal treatment of PCT gel (titanium peroxo complex). The nanoparticles had a rod format with average diameter of 12 nm and an average length of 40 nm with predominantly of rutile crystallographic phase. Subsequently, PHBV nanocomposites were prepared with different proportions of TiO2 nanoparticles (1%, 2.5% and 5% w/w) and compared with the neat polymer as its physical-chemical and thermal properties. In general, the nanoparticles catalyzed the process of biodegradation and photo-degradation of the PHBV polymer matrix. DSC analysis showed that the Tg of the material decreases with the inclusion of TiO2 and by TGA revealed that the degradation temperature is smaller in nanocomposites compared to pure polymer. While, DMA analysis indicated that there was an increase in the damping properties of the nanocomposites compared to PHBV. Finally, mats were prepared by electrospinning to verify cell viability of the nanocomposites. SEM analyzes showed the formation of interconnected continuous fibers, so candidates for use in tissue engineering. Thus, the study of cell viability was conducted in the nanocomposites, which showed that the cells growth on PHBV mats showed good cell adhesion and proliferation rate and, in general, treatment with TiO2 increased cell growth. Membranes prepared by spin-coating technique showed very thin thickness that ranged from 3.8 ?m to 9.1 ?m.