Electrospun (bio)polymeric fibers have attracted widespread interest as functional materials with suitable morphology and properties for their use as tissue engineering scaffolds and/or wound dressings. The fibrous/porous morphology of this type of materials promotes the adhesion and proliferation of tissue cells, but on the other hand, pathogenic microorganisms unfortunately can also be attached to the fibers, thus leading to serious infections and consequently to the immediate removal of the scaffolds or wound dressings, which may imply greater tissue damage. In this context, this review addresses the more recent approaches based on electrospinning and related techniques for developing composite (bio)polymeric fibers with tailored antimicrobial properties either by using mere electrospinning for the incorporation of well-defined antimicrobial nanoparticles (silver, gold, titanium dioxide, zinc oxide, copper oxide, etc.) or by resorting to the combination of electrospraying and electrospinning for the generation of nanoparticle-coated fibers, as well as coaxial electrospinning for obtaining fibers with nanoparticle-rich surface.

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The effect of different variables (precursor reagents, temperature, irradiation time, microwave radiation power, and additives addition) on the final morphology of nano-ZnO obtained through the microwave assisted technique has been investigated. The characterization of the samples has been carried out by field emission scanning electron microscopy (FE-SEM) in transmission mode, infrared (FTIR), UV-Vis spectroscopy, and powder X-ray diffraction (XRD). The results showed that all the above-mentioned variables influenced to some extent the shape and/or size of the synthetized nanoparticles. In particular, the addition of an anionic surfactant (sodium di-2-ethylhexyl-sulfosuccinate (AOT)) to the reaction mixture allowed the synthesis of smaller hexagonal prismatic particles (100 nm), which show a significant increase in UV absorption.

This investigation concerns the design of poly(3-hydroxybutyrate) (PHB)-based nanofibrous hybrid materials containing zinc oxide nanoparticles (nano-ZnO) by means of two electro-hydrodynamic techniques, i.e., electrospinning of polymer/nano-ZnO solutions and the combination of electrospinning of polymer solutions with electrospraying of nano-ZnO dispersions. The analysis of the physical properties associated with precursory solutions was performed in order to understand the final morphology of the corresponding nanofibers. The obtained PHB/nano-ZnO mats showed uniform fiber morphology with an average porosity ca. 85 % with enhanced thermal stability compared to that of pristine PHB. Differential scanning calorimetry was also used to determine the influence of ZnO nanoparticles in the phase transitions of as-spun PHB nanofibers. Furthermore, the antibacterial performance against E. coli and S. aureus proved to be dependent on the elaboration technique, thus permitting the design of novel bacteriostatic or bactericidal PHB/nano-ZnO nanofibrous composites.

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This work addresses a systematic study for the process development and optimization of poly(d,l‐lactic acid) (PDLLA) submicrometer fibers utilizing the centrifugal spinning technique known as Forcespinning. This study analyzes the effect of polymer concentration (8, 10, and 12 wt %) and angular speed on the fiber morphology, diameter distribution, and fiber yield. The increase in polymer concentration and angular speed favored the formation of continuous and homogeneous submicrometer fibers with an absence of bead formation and higher output. The optimal conditions were established considering the morphological characteristics that exhibit a greater surface area (homogeneous and submicrometer fibers); and they were achieved at a polymer concentration of 10 wt % at an angular speed ranging from 8000 to 10 000 rpm. Optimization of PDLLA submicrometer fiber fabrication lays the groundwork for scaling up the process and serves as a platform to further develop promising applications of PDLLA nonwoven mats, particularly in the biomedical area such as in scaffolds for tissue engineering. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47643.

The kinetics of the thermal decomposition reaction of diethyl ketone triperoxide (3,3,6,6,9,9‐hexaethyl‐1,2,4,5,7,8‐hexaoxacyclononane, DEKT) in chlorobenzene solution were studied in the temperature range 99.0–148.0°C and at initial concentrations of (1.65–4.97) × 10−2 M. The thermolysis of DEKT follows a first‐order kinetic law up to at least ca 80% triperoxide conversion. The activation parameter values for the initial O—O bond rupture in chlorobenzene (ΔH‡=134.6±1.7 kJ mol−1; ΔS‡ = 4.2 ± 3.8 J mol−1 K−1) and the reaction products observed support a stepwise reaction mechanism which includes as a first step the unimolecular homolytic cleavage of one peroxidic bond of the DEKT molecule giving rise to a biradical as intermediate. Additionally, the results obtained were compared with those obtained in toluene, toluene–styrene (50%, v/v) and chlorobenzene–styrene (50%, v/v) solution, showing that the decomposition reaction is strongly solvent dependant. Further, the biradical intermediate obtained in all cases was used to initiate styrene polymerization. It was demonstrated that DEKT can effectively act as initiator in styrene polymerization and its performance is similar to that presented by a multifunctional initiator giving rise to high molecular weight polystyrene at a high reaction rate. Copyright © 2004 John Wiley & Sons, Ltd.