Organic nanoparticulate photochromes

Photochromic organic dyes can be widely used in materials for optically rewritable data storage, photonic switches, memories, sensors, or actuators. In recent years photochromic materials based on nanoparticles became particularly focused, since they can be dispersed in colloidal aqueous suspensions or incorporated in thin films, avoiding problems of light scattering or shallow light penetration in bulk materials. Spiropyrans, spirooxazines and diarylethenes were by far the most researched photochromes in nanoparticulate systems. Great effort was made to investigate photochromic dyes incorporated into organic nanoparticles via self-assembly strategies, covalent linkage or dispersion of the molecular species in polymers (doping). Nanoparticles composed of solely photochromic dyes were prepared by laser ablation and reprecipitation techniques. Photochromic dyes were microencapsulated by self-assembly, soap free-, emulsion/microemulsion/miniemulsion or free radical- (co)polymerization. Sol-gel processing from silane precursors to poly(organo)siloxane matrix is a common method to synthesize doped or core-shell photochromic organogels. Coloured forms of some photochromes display fluorescence; however, a more effective strategy for fluorescence modulation with photochromic molecules is integrating them, covalently or noncovalently, with a separate fluorophore in the same nanoparticles. These photoresponsive nanoparticles may find applications particularly in biological fields such as cell labelling and bioimaging. The purpose of this review is to summarize the preparation methods of organic nanoparticles containing photochromic dyes and to investigate their typical properties derived from their nanoparticulate character

The Study of Release of Chlorhexidine from Preparations with Modified Thermosensitive Poly-N-isopropylacrylamide Microspheres

The aim of this study was to investigate and compare the release rates of chlorhexidine (CX) base entrapped in the polymeric beads of modified poly-N-isopropylacrylamides (pNIPAMs) at temperatures below and over the volume phase transition temperature (VPTT) of synthesized polymers: pNIPAM-A with terminal anionic groups resulting from potassium persulfate initiator, pNIPAM-B with cationic amidine terminal groups, and pNIPAM-C comprising anionic terminals, but with increased hydrophobicity maintained by the N-tert-butyl functional groups. The preparations, assessed in vitro below the VPTT, release an initial burst of CX at different time periods between 120 and 240 min, followed by a period of 24 h, when the rate of release remains approximately constant, approaching the zero-order kinetics; the release rates for the polymers beads are as follows: pNIPAM-C>pNIPAM-B>pNIPAM-A. The pattern of release rates at temperature over the VPTT is as follows: pNIPAM-C>pNIPAM-A>pNIPAM-B. In the presence of pNIPAM-C, the duration between the start of the release and the attained minimal inhibitory concentration (MIC) for most of the microbes, in conditions over the VPTT, increased from 60 to 90 min. The release prolongation could be ascribed to some interactions between the practically insoluble CX particle and the hydrophobic functional groups of the polymer

The development of a novel smart material based on colloidal microgels and cotton

Colloidal microgels are often described as “smart” due to their ability to undergo quite dramatic conformational changes in response to a change in their environmental conditions (e.g. temperature, pH). A range of novel smart materials were developed by the incorporation of colloidal microgels into cotton fabric. A series of microgels have been prepared by a surfactant free emulsion polymerization based on N-isopropylacrylamide (NIPAM) monomer. Poly(NIPAM) is a thermosensitive polymer which undergoes a conformational transition close to the human skin temperature. Poly(NIPAM) was co-polymerized acrylic acid (AA), to prepare pH/temperature-sensitive microgels. Microgel particles were characterized by scanning electron microscopy (SEM), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, and dynamic light scattering (DLS). This research aims at coupling microgel particles onto cotton fibers and comparing between different attachment techniques. The coupling reactions between microgels and cotton cellulose are only feasible if they both have appropriate functionalities. For microgels, this was achieved by using different initiators which introduce different functional groups on the particle surface and different surface charges. Cotton samples were successfully modified by carboxymethylation, periodate oxidation, grafting of 1,2,3,4-butanetetracarboxylic acid, and chloroacetylation in order to target possible reactions with the terminal functional groups of the microgel particles. Microgels were attached to the cotton fabrics using different methods and the bonds formed were determined by ATR-FTIR spectroscopy and SEM. The reaction yields were quantified gravimetrically and the maximum weight increase of cotton samples due to the attached microgels was around 24% (w/w)

Recycling of textile materials

Conferència sobre el reciclatge de materials tèxtils, a càrrec de Bojana Voncina del Department of textile materials design. University of Maribor, dins el marc del 7th International Seminar on Sustainable Technology Development: Sustainable Clothing: Production and Consumption que es va dur a terme del 9 al 20 de juny de 2014.Conferència sobre el reciclatge de materials tèxtils, a càrrec de Bojana Voncina del Department of textile materials design. University of Maribor, dins el marc del 7th International Seminar on Sustainable Technology Development: Sustainable Clothing: Production and Consumption que es va dur a terme del 9 al 20 de juny de 2014

Biodegradation of natural textile materials in soil

World is facing numerous environmental challenges, one of them being the increasing pollution both in theatmosphere and landfi lls. After the goods have been used, they are either buried or burnt. Both ways of disposalare detrimental and hazardous to the environment. The term biodegradation is becoming more andmore important, as it converts materials into water, carbon dioxide and biomass, which present no harm tothe environment. Nowadays, a lot of research is performed on the development of biodegradable polymers,which can “vanish” from the Earth surface after being used. In this respect, this research work was conductedin order to study the biodegradation phenomenon of cellulosic and non-cellulosic textile materials whenburied in soil, for them to be used in our daily lives with maximum effi ciency and after their use, to be disposedof easily with no harmful eff ects to the environment. This research indicates the time span of the uselife of various cellulosic and non-cellulosic materials such as cotton, jute, linen, fl ax, wool when used for thereinforcement of soil. The visual observations and applied microscopic methods revealed that the biodegradationof cellulose textile materials proceeded in a similar way as for non-cellulosic materials, the only differencebeing the time of biodegradation. The non-cellulosic textile material (wool) was relatively more resistantto microorganisms due to its molecular structure and surface.Keywords: biodegradation, composting, natural textile materials, FT-I

Color Build-Up and UV-Protection Performance of Encapsulated Photochromic Dye-Treated Cotton Fabrics

WOS: 000387650000001A spirooxazine-based photochromic dye was encapsulated by an oil-in-water emulsion, solvent evaporation method. The encapsulated dye was applied to cotton fabric by a pad-cure process with different binder types. Ultraviolet (UV) protection was increased with application of the encapsulated photochromic dye. The type of binder used affected the photochromic color build-up during UV irradiation and could modify the UV protection imparted by the encapsulated photochromic dyes on textiles.Scientific and Technical Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109M363]The authors would like to gratefully acknowledge the financial support for this research received through Project No. 109M363 of The Scientific and Technical Research Council of Turkey (TUBITAK)

Preparation of SMART wound dressings based on colloidal microgels and textile fibres

Wound dressings and other types of wound healing technologies are experiencing fast-paced development and rapid growth. As the population ages, demand will continue to rise for advanced dressings used to treat chronic wounds, such as pressure ulcers, venous stasis ulcers, and diabetic ulcers. Moist wound dressings, which facilitate natural wound healing in a cost-effective manner, will be increasingly important. In commercially available hydrogel / gauze wound dressings the gel swells to adsorb wound excreta and provide an efficient non adhesive particle barrier. An alternative to hydrogels are microgels. Essentially discrete colloidal gel particles, as a result of their very high surface area to volume ratio compared to bulk gels, they have a much faster response to external stimuli such as temperature or pH. In response to either an increase or decrease in solvent quality these porous networks shrink and swell reversibly. When swollen the interstitial regions within the polymer matrix are available for further chemistry; such as the incorporation of small molecules. The reversible shrinking and swelling as a function of external stimuli provides a novel drug release system. As the environmental conditions of a wound change over its lifetime, tending to increase in pH if there is an infection combining these discrete polymeric particles with a substrate such as cotton, results in a smart wound dressing