Table of contents

The nanofiber membranes prepared by the electrospinning method have unique properties such as high specific surface area and high porosity with fine pores. These properties led electrospun nanofiber membranes to use for the removal of dye molecules from textile wastewater. In this study, a hydrophobic Thermoplastic Polyurethane (TPU) and a hydrophilic Poly (vinyl alcohol) (PVA) were selected for producing electrospun nanofibers and their sorption capacities were investigated. The largest sorption capacity reached to maximum 88.31 mg/g, belong to BTCA cross-linked PVA membranes due to hydrophilic character of PVA. Contrary to expectation, hydrophobic character of TPU was dominant and incorporation of CD to the TPU nanofibers did not affect the sorption of the TPU membranes, and showed very low adsorption capacity (14.48 mg/g).

There is a growing concern related to the effects of nanomaterials in health and safety.Nanotechnologies are already present in many consumer products, including textiles. "Nanotextiles" can be considered as traditional textiles with the incorporation of nanoparticles. They present often functionalities such as antibacterial, ultraviolet radiation protection, water and dirt repellency, self-cleaning or flame retardancy. Nanoparticles can be released from the textile materials due to different effects (abrasion and other mechanical stresses, sweat, irradiation, washing, temperature changes, etc.). It is then expectable that "nanotextiles" may release individual nanoparticles, agglomerates of nanoparticles or small particles of textile with or without nanoparticles, depending on the type of integration of the nanoparticles in textiles. The most important exposure route of the human body to nanoparticles in case of textiles is skin contact. Several standards are being developed under the auspices of the European Committee for Standardization. In this paper, it is presented the development and application of a test method to evaluate the skin exposure to nanoparticles, to evaluate the transfer of the nanoparticles from the textile to the skin by the effect of abrasion and sweat.

In this systematic study, we describe the influence of various surfactants and polymers on aggregation stability of ZnO nanorods. Triton X-100, PVP and PVA were used to disperse nanorods. The surfactant/polymer stabilizing effect was monitored using the sedimentation study and photographic methods based on the decrease in the height of the interface as a function of time. The dispersion of nanorods when applied to cotton fabric, it exhibited functional properties like antibacterial activity and UV protection. The morphologies of nanorods and functionalized cotton were characterized by using SEM.

Electrospinning is a straightforward, cheap and unique method to produce novel fibers with diameter in the range of 100 nm and even less. Those nanofibers have a wide variety of applications such as: filters, membranes, composite reinforcement, drug delivery, protective barriers, sensors, wound dressings and tissue-engineered scaffolds where their unique properties contribute to product functionality. However, this process is characterized by a chaotic oscillation of the electrospinning jet which leads to the formation of beads an uneven nanofibers. This research work envisages the development of an apparatus to control the deposition of electrospun nanofibers through the use of a series of charged metal rings and the addition of a secondary power source, which enables a greater control over the polymer jet stream.

In this work, the effect of fabrication parameters on silk fibroin (SF) nonwovens obtained by electrospinning were evaluated. Additionally, the relationship between secondary structures and thermal stability of the protein materials, with morphological characteristics of nonwovens obtained were analyzed. Silk fibroin in formic acid solution at 10% w/w was electrospun at 8 cm varying the ratio voltage/distance and flow rate. The nonwovens morphology was observed by Scanning Electron Microscopy (SEM) and fibers diameter were determined with ImageJ software. The changes in the secondary structure of silk fibroin before and after electrospinning were studied by Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC) to evaluate the effect of electrospinning process in the molecular structure of SF. Optimum morphology of SF nonwovens were obtained at R = 1 kV/cm and low flow rate, these process parameters were related to higher contents of crystalline structures in the materials. Results showed that SF nonwovens obtained under controlled process parameters hold great potential to be utilized in several applications such as tissue engineering.

Chitosan is of special interest for biotechnological and medical applications due to its antibacterial, antifungal and other intrinsic physical and chemical properties. The biopolymer can, e.g., be used for biotechnological purposes, as a filter medium, in medical products, etc. In all these applications, the inner surface should be maximized to increase the contact area with the filtered medium etc. and thus the chitosan's efficacy. Chitosan dissolves in acidic solutions, opposite to neutral water. Electrospinning is possible, e.g., by co-spinning with PEO (poly(ethylene oxide)). Tests with different chitosan:PEO ratios revealed that higher PEO fractions resulted in better spinnability and more regular fibre mats, but make stabilization of the fibre structure more challenging.

In recent years, the basic electrospinning setup has undergone many modifications carried out to enhance the quality and improve the functionality of the resulting nanofibers. Being one of these modifications, coaxial electrospinning has attracted great attention. It enables to use different materials in nanofiber production and produce multi-layered and functional nanofibers in one step. In this study, TiO₂ has been added to the shell layer of coaxial nanofibers to develop functional nanofibers which may be used in water treatment applications. The coaxial nanofibers containing TiO₂ in the shell layer are compared to uniaxial nanofibers containing TiO₂ in bulk fiber structure, regarding their morphology and photocatalytic activity. Uniform uniaxial and coaxial nanofibers with TiO₂ were obtained. The average nanofiber diameter of coaxial nanofibers were higher. Coaxial nanofibers, which contained lower amount of TiO₂, displayed similar performance to uniaxial nanofibers with TiO₂ in terms of photocatalytic degradation ability against isoproturon.

Needleless electrospinning operated as a one-stage process producing nanofibres webs from spinning solutions with the corresponding to the final use properties seems has a good future prospects. Complicated spinning solution designing started with the selection of composition and components proportion, pre-processing sequence and parameters establishing for every component and for their mixing. Spinning solution viscosity and electro conductivity together with the spinning distance and intensity of electromagnetic field are main parameters determined spin ability and properties of obtained nanofibers. Influence of some pre-processing parameters of components, combinations of organic and non-organic components and their concentration influence on spinning solution viscosity and conductivity, as well on fibres diameters are under discussion.

Schiff base ligands are regarded as an important class of organic compounds on account of the fact that their complexation ability with transition metal ions. A new monomeric Schiff base Cu(II) complex, [Cu(HL)₂], 1 [H₂L = 2–((E)–(2–hydroxypropylimino)methyl)–4–nitrophenol] has been synthesized and characterized by elemental analysis, UV and IR spectroscopy, single crystal X-ray diffraction and photoluminescence study. While the Schiff base ligand and its Cu(II) complex are excited at λ_ex = 349 nm in UV region, the Schiff base ligand shows a blue emission band at λ_max = 480 nm whereas its Cu(II) complex shows a strong green emission band at λ_max = 520 nm in the solid state at room temperature. The luminescent properties showed that the Schiff base ligand and its Cu(II) complex can be used as novel potential candidates for applications in textile such as UV-protection, antimicrobial, laundry and functional bleaching treatments.

The development of new multifunctional textiles containing nanoparticles (NPs) has a special interest in several applications for pharmaceutical and medical products. Cu, Zn and Ag are the most promising antimicrobial NPs, exhibiting strong antibacterial activities. However, most of antimicrobial textiles coated with NPs are not able to perform a controlled release of NPs because of the high degree of aggregation. The aim of this study is to assess the effect of NPs stabilizers such as citrate, alginate and polyvinyl alcohol (PVA) in Cu, Zn and Ag NPs dispersions. The obtained dispersions were used to develop a new class of antibacterial NPs coatings onto polyamide 6,6 (PA66) and polyester fabrics (PES) by Double Dielectric Barrier (DBD) plasma discharge. Dynamic light scattering (DLS) was used to evaluate the best dispersing agent in terms of size, polydispersity index and zeta potential. Coating efficiency was evaluated by SEM, XPS and FTIR. The washing fastness of the coatings developed was also tested. The results show that the best dispersions were obtained using 2.5% of citrate for ZnO, 5% Alginate for Cu and 2.5% alginate for Ag NPs. SEM, XPS and FTIR analysis shows that DBD is an efficient deposition technique only for Ag and Cu NPs and that better perform in PA66 than PES fabric. The DBD deposition in air display similar results in term of NPS deposition of usually more efficient plasma jets using carrier gas such as N₂ and Ar.

Due to growing demand for production of safe water a search of new materials for water purification is of critical issue. Their production should be of low cost and offers easily scalable manufacturing protocol. In this study, we have described preparation and properties of hydrophilic/oleophobic microfiltration membranes produced by means of wire electrospinning. Selective separation of oil or water was tested for oil-water emulsion by using a dead-end filtration unit. The obtained data allowed us to claim membranes as excellent separators for splitting emulsions.

In this work, poly (styrene-methyl methacrylate-acrylic acid) P(St-MMA-AA) composite nanospheres were deposited onto chitosan-cationized woven cotton fabrics followed by a second layer of chitosan. The deposited photonic crystals (PCs) on the fabrics were evaluated for coating efficiency and resistance, chemical analysis and color variation by optical and SEM microscopy, ATR-FTIR, diffuse reflectance spectroscopy and washing fastness. Chitosan deposition on cotton fabric provided cationic groups on the fiber surface promoting electrostatic interaction with photonic crystals. SEM images of the washed samples indicate that the PCs are firmly coated on the cotton surface only in the chitosan treated sample. The photonic nanospheres show an average diameter of 280 nm and display a face-centered cubic closepacking structure with an average thickness of 10 μm. A further chitosan post-treatment enhances color yield of the samples due to the chitosan transparent covering layer that induce bright reflections where the angles of incidence and reflection are the same. After washing, no photonic crystal can be detected on control fabric surface. However, the sample that received a chitosan post-treatment showed a good washing fastness maintaining a reasonable degree of iridescence. Chitosan fills the spaces between the polymer spheres in the matrix stabilizing the photonic structure. Sizeable variations in lattice spacing will allow color variations using more flexible non-close-packed photonic crystal arrays in chitosan hydrogels matrices.