Cellulose acetate (CA) fibers were obtained by electrospinning and their properties analyzed by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), ...differential scanning calorimeter (DSC) and thermogravimetric analysis. The effect of the polymer concentration on crystallinity and fiber diameter of the obtained material was studied by DSC. The application of the pure polymeric fibers to the discoloration of methylene blue (MB) aqueous solutions in dark and under sunlight irradiation was evaluated with UV–Vis absorption and photoluminescence spectroscopies. Also, the photodegradation of the dye was compared using CA powder and fibers under UV irradiation. The results revealed that the dye molecule discoloration with CA fibers mesh was higher under sunlight irradiation than in dark conditions. The maximum absorption band (664 nm) of MB decreased with the time in the absence and presence of polymer under either solar natural exposition or UV irradiation. The dye organic discoloration efficiency obtained by using electrospun CA mesh was 28% and 98% in dark conditions and under natural solar illumination, respectively. The FTIR showed the interaction of dye organic or sub-products generated with the polymeric component. This work provides a simple method for the discoloration of wastewater effluents using microfibers composed of only one abundant polymeric material, allowing the reduction in the amount of material needed and therefore the manufacturing costs of the adsorbent material.
Polyacrylamide (PAAm) hydrogel containing nanofibers of polyaniline (PANI) has been prepared in order to evaluate it as electric stimuli-responsive material. Amoxicillin was loaded onto chemically ...synthesized PANI nanofibers of large-aspect-ratio. Composite hydrogel was obtained by the in situ incorporation of amoxicillin-loaded PANI during polymerization and reticulation of acrylamide. TEM images of cross sections of PAAm/amoxicillin-loaded PANI composite revealed a continuous 3D nanofiber network of PANI supported by the hydrogel matrix. The antibiotic molecules were accurately released (or sustained) from composite hydrogel in response to application (or removal) of cathodic electrical stimulation. In vitro cytotoxicity evaluation of composite hydrogel extract on mouse subcutaneous connective tissue has shown cell viability higher than 80%. The tuning release profile and minimal toxicity of the material evidenced its potential for electrically controlled drug delivery applications such as implantable devices and transdermal drug delivery systems.
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•Novel extruded films of polyethylene with a content of 20wt% chitosan were obtained.•Compatibilizer PEgMA and glycerol improved the processability of the mixtures.•The compatibilized films showed an ...improvement in the deformation at break.
Novel films of polyethylene and chitosan were obtained using extrusion. These polymers have interesting properties, and processing them with methods that are of high use in the industry, such as the extrusion method, can have a significant effect on the potential applications of these materials. The individual materials were thermally characterized; after this, extruded films of low density polyethylene and chitosan mixtures were prepared with the addition of polyethylene-graft-maleic anhydride as a compatibilizer for the blends, and glycerol, as a plasticizer for chitosan. The use of compatibilizer and plasticizer agents improved the processability and compatibility of the mixtures, as well as their mechanical properties, as revealed by mechanical property measurements and scanning electron microscopy. It was possible to prepare blends with a maximum chitosan content of 20wt%. The material stiffness increased with the increase of chitosan in the sample. FTIR studies revealed the existence of an interaction between the compatibilizer and chitosan.
Controlled drug release systems have the characteristics of eliminating or reducing side effects and producing a therapeutic concentration of the drug that is stable in the body. The synthesis of ...hydrogels from natural polymers allows innovation in new materials that promote more effective, selective and safe therapies, in comparison with hydrogel systems based on synthetic polymers where their main limitation may be their biocompatibility and degradation. For this reason, in this work the synthesis of hydrogels of chitosan crosslinked with glutamic acid is proposed as the basis of new trends in smart materials for their potential use in the controlled release of drugs, the hydrogels were prepared from an amidation reaction between the amino groups of chitosan and the carboxyl groups of
L
-glutamic acid, using
N
-(3-Dimethylaminopropyl)-
N
′-ethylcarbodiimide hydrochloride (EDC) as activator of the carboxyl groups. The hydrogels obtained were characterized by SEM, FTIR, TGA techniques, swelling kinetics and antimicrobial activity. They exhibited excellent swelling capacity and good performance when exposed to different pH and temperature conditions. The bacterial inhibition percentages demonstrated the antimicrobial activity of chitosan hydrogels and the results obtained potentially favored their use as reservoirs for controlled drug release.
Dodecilbenzene sulfonate doped-polyaniline/poly(
n-butyl methacrylate) composites were prepared by cast molding. The electrical, mechanical and morphological behaviors of composite films were ...studied. The tensile strength of the composite increased by approximately a 66% for 15
wt.% of polyaniline and this increase is attributed to the homogeneous distribution and improved interface properties between the conducting particles and the matrix. Qualitative analysis of tensile fracture surfaces reveals the presence of conductive agglomerates with matrix polymer still coating them after failure, giving an indication of a good interfacial interaction of the conducting particles and the thermoplastic matrix. The piezo-resistive behavior of the films at different compositions was measured under tensile loading and the composite shows higher electromechanical sensitivity for films compositions slightly above the percolation threshold
i.e. contents of 4
wt.% and 5
wt.%. The piezo-resistive response had a good reproducibility over five cycles of loading/unloading in the elastic region of deformation. In general, the reversibility of the piezo-resistive behavior revealed that there is a very small hysteresis of the composites, with particle contents close to the threshold and it becomes smaller for higher polyaniline contents, suggesting a potential application of this material in electromechanical devices.
In the present work, polylactic acid (PLA), elastin and gelatin fibers, containing clindamycin, were prepared to test their potential application as wound dressings. They underwent release studies to ...determine the mechanism of drug release through mathematical models. The fibers have a homogeneous morphology, without pores. The studies of FTIR and thermal analysis corroborate the presence of each of the components in the fibers; the results of the feasibility tests showed encouraging percentages with a viability of 82% after 7 days of direct contact of the HUVEC cells with the membranes. Similarly, cell adhesion assays show the presence of viable and stretched cells on the fibers, the tendency of the cells to position themselves on the fibers and follow this conformation was observed. On the other hand, studies of antimicrobial activity against
S. aureus
show us that in fibers loaded with clindamycin they have inhibition halos greater than 8 mm.
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•Novel electroconducting PPy/CNT/alginate nanocomposites were synthesized through in situ chemical polymerization in micellar media.•The method involves H2O2 and small amount of SDS ...as a green approach to form a three-dimensional structure with well-connected domains.•The synergistic combination of pristine CNT and alginate improves the conductivity and stability of PPy-based colloids.•A metoprolol-loaded platform was obtained by the confinement of the synthesized nanocomposite into an alginate network.•The hydrogel matrix produces a hindering effect on drug release in passive conditions.
The development of Green-based methods for preparing polypyrrole (PPy)-containing materials with optimal electroactivity still remains a challenge. We herein report a new green approach for the preparation of PPy/carbon nanotube/alginate multifunctional nanocomposites through H2O2 oxidation in micellar medium. The polymerization conditions were systematically varied to optimize the reaction yield and the material electroconductivity. The pre-polymerization emulsion system was studied by contact angle measurements and dynamic light scattering. The results of zeta potential characterization, field-emission scanning electron and atomic force microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy are discussed in detail, and a consistent mechanism for the nanocomposite formation is proposed. Interestingly, the synergistic combination of pristine carbon nanotubes and the alginate improves the conductivity and stability of PPy-based colloids. Furthermore, a metoprolol-loaded platform, obtained by the confinement of the synthesized nanocomposite into an alginate network, revealed a cumulative release lesser than 10% after five hours of delivery under passive conditions. This behavior seems to be promising to overcome the undesired burst release in stimulus-controlled drug delivery.
Cellulose acetate membranes (M1) with controlled thickness were coated with an electroconductive polymer, and the resulting composites were characterized by SEM, XPS, electrical conductivity, and ...mechanical measurements. A comparative study of M1 coated with polyaniline (PANI) or with polypyrrole (PPy) for adsorption and subsequent desorption of a gold–iodide complex was performed. The PANI-coated M1 (M2) and that coated with PPy (M3) are effective adsorbents for recovery of the AuI
2
−
complex. The adsorption of gold on the membranes was attributed to the exchange between the dopant ions and the AuI
2
−
complex ions. The adsorption equilibrium data fitted the Langmuir isotherm model for both membranes M2 and M3. The desorption of the AuI
2
−
complex with a NH
4
OH solution 3 M reached 97% for M3 membrane. This study shows a convenient method for the recovery of gold through the use of a complex with iodine without cyanide solutions.
Composites that incorporate an electrically conducting filler, the hydrochloric polyaniline (PANI-Cl), into hydroxy-terminated polydimethylsiloxane (HO-PDMS) matrix were evaluated for DC electrical, ...mechanical, thermal, morphological and piezo-resistive properties. The main focus of the study was on the electrical–mechanical behavior of these composites in view of possible piezo-resistive sensor application. The percolation threshold of conductivity was determined to be around 11.5 wt% of PANI-Cl. Compression/expansion cyclic experiments showed that the filler content modified the stiffness, the magnitude of Mullins effect and the hysteresis behavior in elastomeric composites. The piezo-resistive response of composites differed depending on the sample composition and also, on the strain rate. Composites with concentration above the percolation threshold exhibited at least three-order change of its electrical resistance in a narrow interval of maximum 2% of deformation. The piezo-resistive sensitivity and the reproducibility of response suggested the possibility to use this material as a transducer in an electromechanical device.
