Deutsches Textilforschungszentrum Nord-West

Cyclodextrins are non-toxic cyclic polysaccharides. They form inlusion complexes with numerous organic molecules. The physical and chemical properties of the guest molecules change due to complex formation. Thus, for example, the stability of the complexed molecule against light and oxygen increases and the vapor pressure is reduced. The solubility of slightly soluble molecules increases in a cyclodextrin complex. All these and further advantages of cyclodextrins and their complexes can be used for the formulation of cosmetic products. As a result, effects are possible not realizable with common techniques.

A new dyeing process is reported for synthetic fibers and fabrics. The use of super critical fluids, especially supercritical carbon dioxide, as dyeing media completely avoids water pollution. Laboratory results are reported on the dyeing of poly(ethylene tere phthalate) and other synthetic materials and on factors influencing dye uptake and levelness. The fundamentals and future aspects of this new procedure are discussed.

Hybrid biocomposite coatings of ZnO and Ag:ZnO nanoparticles with antibacterial activity were prepared and dispersed in chitosan.

Durable press (DP) or easy care finishing is almost always used for cotton fabrics or textiles with a high content of cellulosic fibers. This finish provides resistance against shrinkage and improved wet and dry wrinkle recovery to cellulosic textiles. Inhibition of easy movement of the cellulose chains by crosslinking with resins/polymers is the mechanism of a DP finish. Initially, derivatives of urea such as urea-formaldehyde and melamine-formaldehyde resins were used. Environmental concerns and the potential danger of formaldehyde led to the introduction of formaldehyde-free finishes. Among them, polycarboxylic acids such as 1,2,3,4-butanetetracarboxylic acids and citric acids are the most promising chemicals. To enhance the flexibility, tensile strength and whiteness of the easy care finished textiles, novel finishing agents have been recently considered; for example, ionic crosslinking, polyamino carboxylic acids and non-ionic polyurethane, as well as employing nano-materials as the catalyst or co-catalyst. The possible application of the easy care treatment with other functional finishes, mainly antimicrobial, flame retardancy and water–oil repellency, has been also been focused upon.

Despite their excellent flame retardant properties, polyphosphazenes are currently not used as flame retardant agents for textile finishing, because a permanent fixation on the substrate surface has failed so far. Here, we present the successful synthesis and characterization of a noncombustible and foam-forming polyphosphazene derivative, that can be immobilized durably on cotton and different cotton/polyester blended fabrics using photoinduced grafting reactions. The flame retardant properties are improved, a higher limiting oxygen index is found, and the modified textiles pass several standardized flammability tests. As flame retardant mechanism a synergistic effect between the immobilized polyphosphazene and the textile substrate was observed. The polyphosphazene finishing induces an earlier decomposition of the material with a reduced mass loss in thermogravimetric analysis. The decomposition of cotton and polyester leads to the formation of phosphorus oxynitride, which forms a protecting barrier layer on the fiber surface. In addition, the permanence of the flame retardant finishing was proven by laundry and abrasion tests.

Throughout human history, textiles have been integral to daily life, but their exploration in catalysis has been rare. Herein, we show a facile and permanent immobilization of organocatalysts on the textile nylon using ultraviolet light. The catalyst and the textile material require no chemical modification for the immobilization. All of the prepared textile-immobilized organocatalysts (a Lewis basic, a Brønsted acidic, and a chiral organocatalyst) display excellent stability, activity, and recyclability for various organic transformations. Very good enantioselectivity (>95:5 enantiomeric ratio) can be maintained for more than 250 cycles of asymmetric catalysis. Practical and straightforward applications of textile organocatalysis may be beneficial for various fields by offering inexpensive and accessible functionalized catalytic materials.

Because of the success of dyeing synthetic fibers with disperse dyes in supercritical carbon dioxide, we have investigated the possibility of dyeing natural fibers with this technique. Experiments are presented for wool and cotton dyeings after a special pretreatment.

Morphological studies of aligned nanofibers scaffolds made of poly(glycerol sebacate)(PGS)/poly( ϵ ‐caprolactone)(PCL) blends for application as corneal tissue scaffolds are presented. Parallel conductive bars are used as ground electrode to generate unidirectional nanofibers. Scaffolds have fibers diameter in the range of 550–300 nm. The structural stability and wettability, especially the in vitro degradation rate, of the electrospun scaffolds can be controlled by regulating the blended ratio of the polymers. The results indicate that PGS/PCL nanofiber scaffolds can be considered as ideal candidates for corneal tissue engineering scaffolds. The particular motivation for this work is to engineer a tissue‐like construct that will mimic the stromal tissue of the cornea.

Excimer-laser-induced ablation of polymers is often accompanied by a modification of the surface morphology at the irradiated regions. Only very recently models have been proposed for this effect, the origin being searched in different absorption properties of crystalline and amorphous material. A study by the authors on synthetic fibers irradiated by the UV laser is in contrast with that assumption and gave evidence of a thermal contribution to laser-polymer interaction. Furthermore, a strong influence of internal or external stress fields is found. On this basis a synergetic understanding of the surface structures is proposed.

Cyclodextrins are cyclic oligosaccharides. These molecules are able to form inclusion complexes with a large number of organic molecules. The properties of cyclodextrins enable them to be used in a variety of different textile applications. Cyclodextrins may act as auxiliaries in washing and dyeing processes, and they can also be fixed onto different fibre surfaces. Owing to the complexing abilities of cyclodextrins, textiles with new functional properties could be made available.

Structural and mechanical properties of aligned PGS/PCL nanofibers for cornea tissue engineering are studied and compared to natural corneal stroma.

An overview of a new dyeing process for dyeing synthetic fibres and fabrics is presented. The use of disperse dyes in supercritical carbon dioxide as dyeing medium completely avoids water pollution and the need of drying. Laboratory results which show that excellent levelness and fastness can be achieved on poly- (ethylene terephthalate) and other synthetic materials are presented. The technical development is described and other potential uses of supercritical fluids in the textile field are discussed.

Abstract A super-hydrophobic character is increasingly required for high-performance technical textiles in order to attain effective liquid repellence, self-cleaning, uni-directional liquid transport, or to create barrier coatings on fiber surfaces. Accordingly, numerous novel approaches to decrease the surface free energy of fibers have been studied in the last years, either employing wet-chemical finishes based on modern chemical developments such as silane chemistry, nanocomposite structures, or physically applied thin layers. Similar to other branches, textile researchers have also tried to mimic the extreme water repellence of several plant and animal surfaces according to the understanding by Cassie and Baxter. The scope of this paper is to give a critical overview of the principles, advantages and disadvantages of several concepts. While leading to high water or even oil repellence, chemical finishes applied using conventional methods — i.e. dipping or padding and ensuing thermal fixation — mostly fail to withstand influences such as mechanical stress — e.g. abrasion, high tensile forces —, climate, aggressive chemical environments, and high temperatures, to which technical textiles are subjected to in use. This is true for conventional fluorocarbons or novel finishes such as silicones. Here, cross-linked layers of non-polar character prove to be superior. These can either be obtained by deposition of inorganic–organic nanocomposites, e.g. using the sol–gel technique, or by deposition of thin layers by physical methods. With regard to the effects of microrough fiber surfaces, present knowledge indicates an inferior durability due to the destruction of the delicate topography in use. In natural systems such as plants, this effect is overcome by self-healing mechanisms which technical products do not possess. Keywords: SUPERHYDROPHOBICTEXTILEFIBERSOL–GELTHIN LAYERSMICROROUGHNESS

In this work, we explore the ability of utilizing hydrogels synthesized from a temperature-sensitive polymer and a polyelectrolyte to desalinate salt water by means of reversible thermally induced absorption and desorption. Thus, the influence of the macromolecular architecture on the swelling/deswelling behavior for such hydrogels was investigated by tailor-made network structures. To this end, a series of chemically cross-linked polymeric hydrogels were synthesized via free radical-initiated copolymerization of sodium acrylate (SA) with the thermoresponsive comonomer N-isopropylacrylamide (NIPAAm) by realizing different structural types. In particular, two different polyNIPAAm macromonomers, either with one acrylate function at the chain end or with additional acrylate functions as side groups were synthesized by controlled polymerization and subsequent polymer-analogous reaction and then used as building blocks. The rheological behaviors of hydrogels and their estimated mesh sizes are discussed. The performance of the hydrogels in terms of swelling and deswelling in both deionized water (DI) and brackish water (2 g/L NaCl) was measured as a function of cross-linking degree and particle size. The salt content could be reduced by 23% in one cycle by using the best performing material.

The antibacterial performance of sol-gel-derived inorganic-organic hybrid polymers filled with ZnO nanoparticles-chitosan against a gram-negative bacterium Escherichia coli and a gram-positive Micrococcus luteus has been investigated. Three different molecular weights (MW) of chitosan (CTS) 1.36 · 10 5 , 2.2 · 10 5 , and 3.0 · 10 5 Da with equal degree of deacetylation (DD, 85%) (coded as S 85-60, He 85-250, and He 85-500) with equal degree of deacetylation (DD, 85%) were examined. ZnO was prepared by the base hydrolysis of zinc acetate in isopropanol using lithium hydroxide (LiOH · H 2 O) to hydrolyze the precursor. Sol-gel-based inorganic-organic hybrid polymers were modified with these oxides and were applied to cellulosic cotton (100%) and cotton/polyester (65/35%) fabrics. Inorganic-organic hybrids polymers were based on 3-glycidyloxypropyltrimethoxysilane (GPTMS). Bacteriological tests were performed in nutrient agar media on solid agar plates and in liquid broth systems using ZnO nanoparticles with average particle size of (40 nm). Our study showed the enhanced antibacterial activity of ZnO nanoparticles chitosan (different MW) of against a gram-negative bacterium Escherichia coli DSMZ 498 and a gram-positive Micrococcus luteus ATCC 9341 in repeated experiments. The antibacterial activity of textile treated with ZnO nanoparticles chitosan increases with decreasing the molecular weight of chitosan.

Thin films of [Cu(3)(btc)(2)](n) (btc = 1,3,5-benzenetricarboxylate) metal organic framework were deposited in a stepwise manner on surfaces of flexible organic polymers. The thickness of films can be precisely controlled. The deposition of the first cycles was monitored by UV-vis spectroscopy. The porosity was proven by the adsorption of pyrazine, which was monitored by FT-IR and thermogravimetric analysis. The deposition of MOF thin films on flexible polymer surfaces might be a new path for the fabrication of functional materials for different applications, such as protection layers for working clothes and gas separation materials in the textile industry.

Abstract A water‐soluble carboxymethyl chitosan was prepared with a view to develop a multifunctional finish on cotton. Carboxymethyl chitosan (CMCTS) was synthesized by chemical reaction of chitosan with monochloroacetic acid under alkaline condition. The water soluble CMCTS was applied to cationized cotton with different concentrations. The treated fabrics were characterized through monitoring the textile physical properties and for the antibacterial activity against Escherichia coli DSMZ 498 and Micrococcus luteus ATCC 9341. The results obtained show that the physical properties of the treated fabrics are improved by increasing the CMCTS concentration, as well as the antibacterial activity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Mono-, oligo- and polyamide rotaxanes with the macrocycle cucurbituril are synthesized easily with high yields by interfacial condensation. The complex of cucurbituril with 1,6-hexanediammonium ion is used as preorganized structure. With different acid and diacid chlorides a great variety of amiderotaxanes and polyrotaxanes can be synthesized. The characterization is difficult due to the low solubility of cucurbituril and rotaxanes. But with the methods of IR, DTA, 1H NMR and elemental analyses, the existence of the rotaxanes is shown.

Abstract In the present study, DOPO-based alkoxysilane (DOPO-ETES) and amido alkoxysilane (DOPO-AmdPTES) were synthesized by one-step and without by-products as halogen-free flame retardants. The flame retardants were applied on cotton fabric utilizing sol–gel method and pad-dry-cure finishing process. The flame retardancy, the thermal stability and the combustion ehaviour of treated cotton were evaluated by surface and bottom edge ignition flame test (according to EN ISO 15025), thermogravimetric analysis (TGA) and micro-scale combustion calorimeter (MCC). Unlike CO/DOPO-ETES sample, cotton treated with DOPO-AmdPTES nanosols exhibits self-extinguishing ehaviour with high char residue, an improvement of the LOI value and a significant reduction of the PHRR, HRC and THR compared to pristine cotton. Cotton finished with DOPO-AmdPTES reveals a semi-durability after ten laundering cycles keeping the flame-retardant properties unchanged. According to the results obtained from TGA-FTIR, Py-GC/MS and XPS, the major activity of flame retardant occurs in the condensed phase via catalytic induced char formation as physical barrier along with the activity in the gas phase derived mainly from the dilution effect. The early degradation of CO/DOPO-AmdPTES compared to CO/DOPO-ETES, triggered by the cleavage of the weak bond between P and C=O, as the DFT study indicated, provides the beneficial effect of this flame retardant on the fire resistance of cellulose. Graphical abstract

The detection of shedded fibers in effluents from textile washing has attracted much attention due to its reported contribution to microplastic pollution. Commonly used analytical methods for fiber detection in liquids are based on filtration with subsequent microscopic analysis and/or gravimetric weighing. These approaches are time-consuming and prone to errors. In this study, an approach based on dynamic image analysis was applied in order to set up an efficient method to analyze fibers in effluents from washing processes. In an initial validation step, reliable information on the counts of fibers and the morphological characteristics were confirmed. For wastewaters from polyester-cotton blends, the chemical nature of the fiber debris (natural vs. synthetic origin) was determined by combining the dynamic image analysis with a chemical pre-treatment. In this study, dynamic image analysis was revealed as a rapid, non-destructive, precise, and reliable technology for the characterization and quantification of the fiber debris, offering a promising approach for fiber analysis in liquids.