排序方式: 共有22条查询结果,搜索用时 31 毫秒
1.
Franciani C. Sentanin Willian R. Caliman Rodrigo C. Sabadini Carla C. S. Cavalheiro Rui F. P. Pereira Maria M. Silva Agnieszka Pawlicka 《Molecules (Basel, Switzerland)》2021,26(8)
Nanocomposite polymer electrolytes (NPEs) were synthesized using sodium alginate (Alg) and either sodium (SCa-3-Na+)- or lithium (SCa-3-Li+)-modified montmorillonite clays. The samples were characterized by structural, optical, and electrical properties. SCa-3-Na+ and SCa-3-Li+ clays’ X-ray structural analyses revealed peaks at 2θ = 7.2° and 6.7° that corresponded to the interlamellar distances of 12.3 and 12.8 Å, respectively. Alg-based NPEs X-ray diffractograms showed exfoliated structures for samples with low clay percentages. The increase of clay content promoted the formation of intercalated structures. Electrochemical Impedance Spectroscopy revealed that Alg-based NPEs with 5 wt% of SCa-3-Na+ clay presented the highest conductivity of 1.96 × 10−2 S/cm2, and Alg with 10 wt% of SCa-3-Li+ showed conductivity of 1.30 × 10−2 S/cm2, both measured at 70 °C. From UV-Vis spectroscopy, it was possible to infer that increasing concentration of clay promoted a decrease of the samples’ transmittance and, consequently, an increase of their reflectance. 相似文献
2.
Denise T. B. De Salvi Hernane S. Barud Agnieszka Pawlicka Ritamara I. Mattos Ellen Raphael Younés Messaddeq Sidney J. L. Ribeiro 《Cellulose (London, England)》2014,21(3):1975-1985
New bacterial cellulose (BC)–triethanolamine (TEA) ion-conducting membranes have been prepared and characterized. The samples were obtained by soaking BC membranes in triethanolamine aqueous solutions and drying. The scanning electron microscopy pictures revealed that the incorporation of TEA in BC membranes covers the cellulose microfibrils. Raman spectra exhibited BC and TEA characteristic group frequencies and thermal analysis evidenced an influence of TEA content on the sample thermal stability. The ion-conductivity as a function of the temperature showed an Arrhenius behavior increasing from 1.8 × 10?5 S/cm at room temperature to 7.0 × 10?4 S/cm at 80 °C for the BC–TEA 1 M sample. 相似文献
3.
A hybrid PDMS/glass microfluidic system for evaluation of the efficiency of photodynamic therapy is presented. 5-aminolevulinic acid (ALA) was used as a precursor of photosensitizer. The geometry of the microdevice presented in this paper enables to test different concentrations of the photosensitizer in a single assay. The viability of the A549 cells was determined 24 h after PDT procedure (irradiation with light which induced a photosensitizer accumulated in carcinoma cells, λ = 625 nm). The presented results confirmed the possibility to perform the photodynamic therapy process in vitro in microscale and the possibility to assess its effectiveness. Moreover, because two identical microstructures on a single chip were performed, the microchip can be used for examination simultaneously various cell lines (carcinoma and normal) or various photosensitizers. 相似文献
4.
J. P. Mendes J. M. S. S. Esperança M. J. Medeiros A. Pawlicka 《Molecular Crystals and Liquid Crystals》2017,643(1):266-273
New polymer electrolytes (PEs), potentially interesting for solid-state electrochemical devices applications, were synthesized by a solvent casting method using pectin and ionic liquid (IL) N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium bis(trifluoromethylsulfonyl)imide ([N1 1 1 2(OH)] [NTf2]. The resulting electrolytes besides being moderately homogenous and thermally stable below 155°C, they also exhibited good mechanical properties. The SPE membranes were analyzed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and complex impedance spectroscopy. 相似文献
5.
Cholant C. M. Westphal T. M. Balboni R. D. C. Moura E. A. Gündel A. Flores W. H. Pawlicka A. Avellaneda C. O 《Journal of Solid State Electrochemistry》2017,21(5):1509-1515
Journal of Solid State Electrochemistry - Pure and doped vanadium pentoxide (V2O5, V2O5/MoO3) thin films were prepared by sol-gel method and dip coating technique. Furthermore, they were... 相似文献
6.
César O. Avellaneda Karim Dahmouche Luis O.S. Bulhões Agnieszka Pawlicka 《Journal of Sol-Gel Science and Technology》2000,19(1-3):447-451
Electrochemical lithium intercalation in thin films of CeO2-TiO2 and WO3, prepared by the sol-gel technique was investigated with cyclic voltammetry and spectroelectrochemical techniques in propylene carbonate solutions. A solid state system having the configuration WO3/Ormolyte/CeO2-TiO2 has been assembled. The solid electrolyte, an organically modified electrolyte (ormolyte), was prepared with different [O]/[Li] ratios. The transmittance variation of this system during a potentiostatic step from –0.7 V to 0.8 V was about 35% at 550 nm. 相似文献
7.
8.
Amal Al-Kahlout Diogo Vieira César O. Avellaneda Edson R. Leite Michel A. Aegerter Agnieszka Pawlicka 《Ionics》2010,16(1):13-19
Proton-conducting gel polymer electrolytes based on gelatin plasticized with glycerol and containing acetic acid were investigated,
characterized, and applied to electrochromic window. For glycerol contents varying from 7% to 48%, the conductivity of the
uniform and predominantly amorphous gel electrolyte was found to follow a Vogel–Tamman–Fulcher behavior with the temperature.
Typically, for the electrolyte chosen to make 7 × 2 cm2 electrochromic smart window with the configuration: glass/fluor-doped tin oxide (FTO)/WO3/gelatin electrolyte/CeO2–TiO2/FTO/glass and containing 28% of glycerol, the conductivities were found to be of the order of 5 × 10−5 S/cm at room temperature and 3.6 × 10−4 S/cm at 80 °C. The device was characterized by spectroelectrochemical techniques and was tested up to 10,000 cycles showing
a fast coloring/bleaching behavior, where the coloring process was achieved in 10 s and the bleaching in 2 s. The transmission
variation at the wavelength of 550 nm was about 15%. The cyclic voltammograms showed a very good reversibility of the cathodic/anodic
processes, and the charge density was about 3.5 mC/cm2. The memory tests showed that the transmittance in the colored state increased by 8% in 90 min after removing the potential. 相似文献
9.
Thermo-sensitive chitosan–cellulose derivative hydrogels: swelling behaviour and morphologic studies
Sandra Cerqueira Barros Ana Alves da Silva Diana Barbosa Costa Ivana Cesarino Carlos M. Costa Senentxu Lanceros-Méndez Agnieszka Pawlicka Maria Manuela Silva 《Cellulose (London, England)》2014,21(6):4531-4544
Hydrogels are three-dimensional, hydrophilic, polymer networks that are able to imbibe large amounts of water or biological fluids, while maintaining their dimensional stability. The polymer binding might be achieved by chemical or physical interactions. Physical crosslinking of a polymer to form its hydrogel, might be accomplished either by casting-solvent evaporation (SC) method or by freeze–thaw (FT) technique. The physical hydrogels, especially the ones based on natural biopolymers, like polysaccharides, are being widely used in industry and medicine due to their favourable properties: biocompatibility; biodegradability; low toxicity and eco-friendly characteristics. Polysaccharides, like chitosan (CH) and (hydroxypropyl)methyl cellulose (HPMC) have gained great attention due to its stimuli sensitive properties: pH and temperature responsiveness, respectively. Thus, within this work we have developed physically crosslinked CH:HPMC hydrogel films, using both SC and FT techniques. The attained CH:HPMC membranes were evaluated in terms of their swelling, thermal (low critical solution temperature—LCST), structural (attenuated total reflectance Fourier transform infrared spectroscopy) and morphological (scanning electron microscopy and atomic force microscopy) properties. According to these results, the developed membranes exhibit a good miscibility between the two component biopolymers. Moreover, the CH:HPMC membranes exhibit a high swelling capacity (SWFT = 1,172 and SWSC = 7,323), a low surface roughness (Sq = 5.6–9.5 nm) and an elevated LCST (LCST = 85.2–87.5 °C). The stimuli sensitive behaviour makes hydrogels appealing for the design of smart devices applicable in a variety of technological fields. In our particular case, we envisage the application of such materials as active substances (moisturisers, antiperspirants and scents) delivers, into textile substrates in a controlled manner. 相似文献
10.
R. I. Mattos C. E. Tambelli E. Raphael I. D. A. Silva C. J. Magon J. P. Donoso A. Pawlicka 《Cellulose (London, England)》2014,21(4):2247-2259
Polysaccharide- and gelatin-based bioblends and polyblends were synthesized and characterized by complex impedance spectroscopy, proton nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR). Higher ionic conductivities of 7.9 × 10?5 S/cm at room temperature and 2.5 × 10?3 S/cm at 80 °C were obtained for the agar-chitosan polyblends. For all samples, the activation energies, calculated from the Arrhenius plot of ionic conductivity and from the onset of NMR line narrowing, are in the range 0.30–0.86 and 0.38–0.57 eV, respectively. The glass transition temperatures (T g NMR ) varied from 200 to 215 K, depending on the sample composition. The temperature dependence of the 1H spin–lattice relaxation revealed two distinct proton dynamics. The EPR spectra are characteristic of Cu2 ions in tetragonally distorted octahedral sites. Quantitative analysis of the EPR spin Hamiltonian g || and A || parameters revealed copper ions complexed by nitrogens and oxygens in the samples containing chitosan or gelatin and only by oxygens in agar-based ones. The in-plane π bonding is less covalent for the gelatin and chitosan blends. Results suggest that natural bioblends and polyblends are interesting systems to be used in materials science engineering. 相似文献