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Solution blow spinning (SBS) is a recent technology to produce polymer micro- and nanofibers, including nanocomposites loaded with a wide range of nanoparticles. Because of its novelty, various studies about the properties of the produced materials are necessary, especially those related to material stability. In the present study, poly(lactic acid) (PLA)/titanium dioxide anatase (TiO2) nanocomposite fibers, with different TiO2 percentages, were produced by the SBS method. The spun nanocomposite fibers were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, thermogravimetric analysis and differential scanning calorimetry (DSC). Moreover, the photocatalytic degradation of Rhodamine B (RhB) dye and PLA degradation by UV-C lamps were investigated. SEM and TEM micrographs show that the SBS method produced PLA/TiO2 nanofibers with uniform morphology and without beads. The DSC analyses and X-ray diffraction patterns show that incorporation of TiO2 nanoparticles could influence the PLA nanocomposite crystallinity. PLA photocatalytic degradation experiments demonstrate that the weight loss of the polymer increases with an increase in TiO2 content. The present results indicate that the SBS method can be used to produce biodegradable nanocomposite fibers with good properties and potential applications.

Made available in DSpace on 2018-11-26T17:56:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) National Institute for Science and Technology on Organic Electronics Titanium dioxide (TiO2) is used in a range of applications such as photocatalysis and sensor devices. In this work, TiO2 nanoparticles (TiO(2)NPs) in the crystallographic forms anatase and rutile were prepared by the green route. The method involves dissolving titanium oxysulfate (TiOSO4) powder in hydrogen peroxide (H2O2) solution and subsequent thermal treatment of the resultant amorphous precipitate. X-ray diffraction (XRD) was used to follow the structural evolution of the amorphous precipitate, and microstructure analysis was realized with Rietveld refinement. In addition, the photocatalytic activity of the synthesized TiO(2)NPs was evaluated by studying the degradation of Rhodamine B (RhB) dye. The highest photocatalytic activity was observed for TiO2 obtained at 600 A degrees C in the crystallographic form anatase. Univ Sao Paulo, Inst Fis Sao Carlos, Sao Paulo, SP, Brazil Univ Estadual Paulista, Fac Engn, Ave Brasil 56, Ilha Solteira, SP, Brazil Univ Fed Mato Grosso, Dept Quim, BR-78060900 Cuiaba, MT, Brazil Embrapa Instrumentacao, Rua Quinze Novembro 1452, BR-13560970 Sao Carlos, SP, Brazil Univ Estadual Paulista, Fac Engn, Ave Brasil 56, Ilha Solteira, SP, Brazil CNPq: 454704/2014-3 CNPq: 152036/2016-4 FAPESP: 2011/11065-0 National Institute for Science and Technology on Organic Electronics: CNPq 573762/2008-2 National Institute for Science and Technology on Organic Electronics: FAPESP 2008/57706-4

Mixed rutile-anatase TiO2 nanoparticles were synthesized by hydrothermal treatment under acidic conditions and incor- porated into poly(vinyl alcohol) (PVA). These nanocomposites were electrospun to produce nanofibers of PVA/TiO2, which were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The photocatalytic degradation of Rhodamine B and degradation of the polymer by UV-C lamps were also investigated. The results showed that TiO2 nanoparticles did not change the morphology and thermal behavior of the nanofiber polymer, but were effective in modifying the UV absorption of PVA without reducing its stability. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 4463-4469, 2013

A técnica de eletrofiação é conhecida desde a década de 1930, porém, somente com o advento das novas aplicações da nanotecnologia esta importante técnica foi re-descoberta. As potencialidades de nanofibras, de tamanhos da ordem de 50 a 500 nm e com extensão micrométrica, têm sido investigadas para diferentes materiais, com resultados promissores em diferentes aplicações. Nesta primeira parte, este trabalho de revisão propôs-se a detalhar as bases fundamentais do processo de eletrofiação. São descritas as influências das variáveis de processo, como campo aplicado, distância de trabalho, velocidade de rotação do coletor e de injeção da solução. Variáveis associadas ao sistema, como tipo de solvente e polímero de interesse, também são discutidas. The electrospinning technique has been known since the 1930s, but only with the advent of new nanotechnology applications this technique was re-discovered and became important for production of nanomaterials. The potential for obtaining different nanofibers with sizes ranging from 50 to 500 nm and micrometer length has been investigated for different materials, with promising results in different applications. The first part of this review is aimed at describing the fundamentals of the electrospinning process. We describe the influence of process variables such as applied field, working distance, speed of rotation of the collector and solution injecting flow rate. The variables associated to this system, such as type of solvent and polymer of interest, are also discussed.

Nano and submicrometric fibers of poly(D,L-lactide) (PDLLA or PLA) were spun from solutions using a solution blow spinning (SBS) apparatus. Fiber morphology and diameter were investigated by scanning electron microscopy as a function of polymer concentration, feed rate, and air pressure. A more systematic understanding of the SBS process parameters was obtained, and a quantitative relationship between these parameters and average fiber diameter was established by design of experiments and response surface methodology. It was observed that polymer concentration played an important role in fiber diameter, which ranges from 70 to 2000 nm, and its distribution. Lower polymer concentration tended to increase the formation of bead-on-string structures, whereas smooth fibers were formed at higher concentrations. Fiber diameter tended to increase with polymer concentration and decrease with feed rate. Based on these results, optimal conditions could be obtained for solution-blow spun fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

In this study, PVA/TiO2 anatase nanocomposite fibers were prepared successfully by electrospinning. The nanofibers were characterized by SEM, XRD, Raman spectroscopy, EDS, TEM and UV-Vis diffuse reflectance spectroscopy. The characterization showed that the average diameters obtained are dependent of the total loading used. The TiO2 loading showed to be effective in the nanocomposite, changing the UV absorbance but significantly accelerating the degradation of the polymer. This aspect may be useful in order to improve the biodegradability of this polymer by reducing chain lengths.

Em artigo de revisão anterior[1], o processo de eletrofiação foi discutido, incluindo suas bases teóricas e experimentais, e a obtenção de diferentes nanofibras de materiais poliméricos. Neste segundo artigo de revisão, são abordados os aspectos relacionados à aplicação de materiais eletrofiados em diferentes áreas, como médica, agrícola, sensores, processamento de outros materiais, entre outras. São também discutidas as técnicas de caracterização utilizadas mais frequentemente nestes materiais, e suas potencialidades. Esta segunda revisão é complementar à anterior e segue, em seus aspectos gerais, a mesma terminologia. In our previous review[1], the process of electrospinning was discussed on the basis of theoretical and experimental aspects toward preparation of different polymeric nanofibers. In this second review, we focus on the aspects related to the application of electrospun materials in various fields such as medicine, agriculture, sensors, and processing of other materials. We discuss the most often characterization techniques used for these materials and their potential. This review complements the previous one and uses the same terminology.

In this study, PVA/TiO2 anatase nanocomposite fibers were prepared successfully by electrospinning. The nanofibers were characterized by SEM, XRD, Raman spectroscopy, EDS, TEM and UV-Vis diffuse reflectance spectroscopy. The characterization showed that the average diameters obtained are dependent of the total loading used. The TiO2 loading showed to be effective in the nanocomposite, changing the UV absorbance but significantly accelerating the degradation of the polymer. This aspect may be useful in order to improve the biodegradability of this polymer by reducing chain lengths.