Nanocrystalline anatase titanium dioxide films were successfully produced on cotton fabrics from alkoxide solutions under ambient pressure using the low temperature sol-gel process. At a temperature as low as 40°C, only anatase phase formed from X-ray diffraction spectroscopy (XRD). Field scanning electron microscopy (FESEM) images show the formation of uniform continuous films of titanium dioxide on cotton fabrics. The self-cleaning properties of these fabrics were evaluated by measuring anti-bacterial activities and the decomposition of a colorant Neolan Blue 2G. The results indicated that anatase treated cotton fabrics exhibited good self-cleaning performance.

We have utilized the fact that syndiotactic and isotactic Poly(methyl methacrylate) {PMMA} form a stereocomplex to spin semi-crystalline PMMA fibers. Our goal is to produce oriented semi-crystalline fibers with a high enough melting point to withstand atactic-PMMA processing conditions. We successfully developed stereocomplex PMMA fibers by wet spinning and gel spinning, and characterized their properties by means of differential scanning calorimetry, optical/electron microscopy, mechanical testing and X-ray crystallography. Stereocomplex fibers from gel spinning have highest melting points and polymer chain orientation, hence are the best reinforcing agents. We are currently working on producing self-reinforced composites using these fibers.

The world is becoming more health conscious and as a result healthcare is evolving in many ways. Wearable computing is assisting with this evolution, finding its place in many biomedical applications where real-time monitoring of general health indicators is required. However, the inconvenience of connecting sensors through wires, which not only incurs high maintenance, limits the freedom of the person therefore hampering a true reflection of the person's actions. By using sensors attached to wireless sensor nodes, this constraint is removed. Also in order to be “wearable” the sensors must be comfortable, a factor often overlooked by traditional sensors, where functionality and robustness are of higher importance. This work is focused on the use of foam-based pressure sensors and similar textile-based sensors for monitoring the ambulatory movements of the wearer. Characterization of the molecular nature of the materials and their environment are presented. We find these sensors to be successful in detecting the movement events without imposing on the daily activity of the wearer.

This paper studies a flexible strain sensor from PPy-coated fabric prepared by a chemical vapor deposition procedure under low temperature. The mechanisms of its strain sensing behavior were investigated. In-situ tensile tests in a scanning electron microscope (SEM) were conducted for PPy-coated electrically conducting yarns prepared in the same procedure as that for the PPy-coated fabric. The results exhibited the developed PPy-coated fabric possessed the high strain sensitivity and the large workable strain range, which attribute to the high performance of PPy-coated PU fibers and the crack-opening and crack-closing mechanism happened on the surface of PU fibers, as well as the excellent properties of knitted fabric structure.

A number of natural and synthetic, and biodegradable polymers were investigated and remain to be elucidated for both soft and hard tissue repair, and for possible construction of excipient therapeutic templates. Nonwoven matrices from poly (ε-caprolactone) (PCL) homopolymers and poly (L-lactide/ε-caprolactone) (PLLA/CL) copolymers by electrospinning process were investigated for possible applications in burn/wound dressings. Efforts are currently underway to control the release characteristics of these biodegradable fibers by varying aliphatic polyesters. This perspective will have a profound effect on the time-controlled transport of vaccine to a targeted site. These materials will play a key role in developing novel chemotherapeutic agents that could be important in targeting specific genes and may provide selective control of gene expression. Furthermore, these fibers-by-design address many issues relating to the fundamental challenges in the synthesis of novel, biocompatible and safe delivery of vaccine and nanofiber materials to foster antibacterial and/or hygienic functionality, System-on-Fibers (SoF), and will have tremendous application in global security and defense.

In order to bring widely distributed polysaccharides materials into more medical applications, cotton fiber surfaces were modified into substrates for apatite deposition. Using a solid phase reaction, cotton fibers were conveniently carboxylated in large scale. The carboxylated cotton fibers were coated by apatite in a biomimetic way. Through soaking in a concentrated simulated body fluid (SBF × 5), nano-size apatite particles rapidly and finely grew on the fiber surfaces. The nucleation and growth of apatite was investigated with the aid of scanning electron microscopy (SEM). In comparison to pure cotton, the cotton coated with apatite showed improved cell affinity to osteoblast-like cells.

Tetracene single crystals were prepared by the vapor transport method. The polyimide films were used for both substrate and gate dielectric layer. The single-crystal FETs should perform better than thin film transistors. Very thin crystals (~1 μm) were adhered to the substrate by due to electrostatic forces. The mobility of tetracene single-crystal field-effect transistors reaches the room-temperature value of 5×10-4 cm2/Vs.

We present a fluid dynamics model for the drawing of hollow multilayer polymer optical fiber. A newtonian model is considered assuming slender geometries. Hollow core collapse during drawing and layer thickness non-uniformity are investigated as a function of draw temperature, draw ratio, feeding speed, core pressurization and mismatch of material properties in a multilayer.

By incorporating optical fiber based devices into woven and non-woven fabrics, one can distribute these devices across large areas. In this work, novel fiber optic devices with nanofunctionality are developed by incorporating metallic and semiconducting films and nanoparticles inside the optical fibers. This is accomplished by first depositing the material of interest on the tip of the optical fiber, then overcoating the fiber with a protective layer of silicon dioxide before fusing this structure to an optical fiber. This results in a continuous fiber that can be woven, or placed into nonwoven textiles. In this study the incorporation of gold nanoparticles and vanadium oxide compounds into the core of optical fibers and an in-line Fabry-Perot sensor using these techniques are described.

Conductive-polymer coated fabrics have been investigated as intelligent materials in the past years. In this paper, a flexible fabric strain sensor coated with polypyrrole is reported, which is featured with high sensitivity, good stability and large deformation. It is fabricated by chemical vapor deposition at low temperature. The effects of temperature, humidity, acid and alkaline medium have been assessed. The conductivity-strain tests reveal the sensor exhibits a high strain sensitivity of ~160 for a deformation as large as 50%, while its good stability is indicated by a small loss of conductivity after the thermal and humidity aging tests, and supported by the slight change in conductivity and sensitivity over a storage of eighteen months. The acid and alkaline solution mainly decreased their initial conductivity but have the slight effect to their sensitivity. The flexible fabric strain sensor is expected to be a promising “soft” smart material in the smart garment, wearable hardware and biomedical applications.

Fiber coating is an effective way to impart smartness to a fiber. Die coating is a process that utilizes a die to control the thickness and concentricity of the coating layer. In the present work the die coating mechanism is studied numerically. A mathematical model for the fiber coating thickness has been developed. Compared with the previous work, the proposed model considers the effect of gravity force to get the general solution. The shear rate acting on the fiber surface is proportional to the fiber draw speed in an unpressurized applicator and can be minimized in a pressurized applicator through the applied external pressure. A serials of experiments using open-cup and pressurized applicators have been designed and conducted to measure simultaneously the coating speed and coating thickness in the coating process. It was found that the gravity may be an important driving force for the coating flow when the drawing velocity is small and the viscous force decreases, but may be relatively insignificant for high speed coating process. The calculated results were compared with the experimental data and a good agreement was obtained.

Poly(vinylidene fluoride) (PVDF) is well known for its ferroelectric and piezoelectric properties. Currently, this polymer is used in applications in the form of films. PVDF fibers are expected to open up exciting new opportunities such as design and use of active textiles and composites. It is well-known that synthetic fiber properties improve substantially with the decrease of their diameter. However, conventional mechanical fiber spinning processes usually produce fibers with diameters in the range from tens to hundreds of microns. In this work, ultrafine, submicron-diameter continuous PVDF nanofibers were fabricated by electrospinning method. The method consists of spinning polymer solutions in high electric fields. Effects of process parameters on nanofiber diameter and morphology were studied. XRD and FTIR analyses of PVDF nanofibers were performed. The latter indicated that the initial á phase of the raw material was converted to â phase PVDF during electrospinning. As â phase is primarily responsible for the piezo- and ferroelectric properties of PVDF, the latter result is very encouraging. The demonstrated novel continuous PVDF nanofibers can be used in nanostructured active textiles and composites and can lead to unusual new designs for actuators and sensors.

We have printed arrays of strain sensors on textiles by inkjet printing of conducting lines and piezoresistive polymer (PEDOT) in order to provide detailed information about the response of a fabric in use. Conducting polymer has been printed onto polyamide and cellulose woven fabrics to form sensors using a modified HP inkjet print-head and X-Y linear positioning table. Good penetration and attachment is found on mercerized cotton but not on polyamide. Silver nitrate lines have been printed onto polyamide and converted to silver connectors by electroless plating. We observed that resistance of silver lines ranged from 0.7-1.5Ω/cm whereas for the conducting polymer it was 1-3 kΩ/mm by a four point probe method. The conducting polymer formed a surface coat on the fabric and also penetrated the weave. On stretching, the surface layer tended to crack but the embedded polymer acts as a strain gauge with a gauge factor of about 5. On the other hand the silver showed minimal change in resistance with stretching, as is required for connectors. Sensitivity towards temperature and humidity and the effect of orientation to stress and weave directions will be reported. Preliminary experiments show that these sensors attached to a sleeve could be effective for monitoring human joint motion.

This paper reports on layer-by-layer (LbL) self-assembly of poly (3, 4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) conducting polymer on lignocellulose wood microfibers to make conducting paper. Polycation such as poly(allylamine hydrochloride) (PAH) was used with polyanionic PEDOT-PSS to construct the multilayers. The physical characterization of the microfiber was done using roughness step tester (RST) and surface profilometer (TENCOR). Thickness of the coated film was estimated using a quartz crystal micro-balance. Current – Voltage characterization was performed using a Keithley measurement system after each self-assembly of PEDOT-PSS to study the electrical properties of the coated film. It was observed that the conductivity of the microfiber was proportional to the number of polyelectrolyte bilayers deposited. The measured conductivities ranged from (1 to 5) × 10-3 Scm-1 to 1 to 10 Scm-1 for different bilayers of PEDOT-PSS on wood microfibers. It was also observed that the conductivity of the nano-coated fibers is dependent upon the salt concentration used in PAH polycations to from the multilayer. In this work we are developing scale integration from nano, to micro and macro (nanocoating-microfibers-macropaper). The results obtained show great promise for the development of smart paper technology and its contribution to the economic development of the nation.

The conductive polymer poly (3,4-Ethylenedioxythiophene) (PEDOT) is a low band-gap polymer with high charge mobility and good thermal and chemical stability. Nanosized Ag particles have found many potential applications in technical fields because of their reduced sizes, high surface-to-volume ratio, and relatively high chemical stability in air. In this report, 3,4-Ethylenedioxythiophene (EDOT) was used as the reductant for the first time in the preparation of silver nanoparticles by the reduction of AgNO3 in water. And Ag/PEDOT nanoparticles composites conducting films deposited by inkjet printing technique on plastic substrates.

This paper presents an approach for decoding the pressure information exerted over a piece of fabric by means of resistive sensing. The proposed sensor includes a distributed resistive grids constructed by two systems of orthogonally contacted electrical conductive yarns, with no external sensing element to be attached on the fabric. Since the conductive yarns serve as the sensing and wiring elements simultaneously, this design simplifies the fabrication process, reduces the cost and makes the production of large area flexible pressure sensor possible. The location of the pressure applied on the fabric can be identified by detecting the position where the change of the resistances occurs between two embroidered yarns. Meanwhile, the magnitude of the pressure can be acquired by measuring the variations of the resistance. In order to eliminate the “crosstalk” effect between adjoining fibers, the yarns were separately wired on the fabric surface.

New stable silver oxide suspension in chitosan solution was prepared from a mixture of silver nitrate and chitosan in dilute acetic acid as precursor, in which the complex interactions between silver ion and chitosan was also investigated through various instrumentation method seriously. The suspension was charactized through laser scan, infrared ray spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis) and X-ray diffraction (XRD), which indicated that the interactions between silver and chitosan in its precursor were destroyed partially. The measurements of the nanoparticles through scanning electron microscopy (SEM) and transmission electron microscopy (TEM) disclosed the spherical profiles of these silver oxide nanoparticles of 10-20nm in average. Cotton fabrics treated by this emulsion were entitled remarkable antibacterial activity against S aureus and E. coli at pH 5 and 7 with sightless color effect and good washing fastness.

The present development of textile market is connected with an ever increasing demand for new functionalities for highly specific applications. At the same time, the industrial supply has been restricted to only a few types of synthetic fibers. Given that background, surface modification became one of the most important topics to create new textiles. Beside other techniques, the functionalisation of fibers by making use of concepts of the nanotechnology is part of our work for several years. Coatings based on nanosols and inorganic-organic hybrid polymers, derived from sol-gel process, have an immense potential for creative modifications of surface properties and can be applied with a comparatively low technical effort and at moderate temperatures. The coatings often combine properties of organic polymers with those of ceramic materials [1-11]. Therefore those hybrid polymers are of an enormous interest for technical textiles. The basic materials offer the opportunity to produce very hard but flexible coatings, especially by filling or modifying the networks with nano-particles. Approaches to modify these systems by various inorganic or organic substances can lead to a huge number of additional functionalities which are increasingly demanded from the textile industries [12-18]. Coatings of a thickness of less then one micron can act as effective barriers against chemical attacks, super-repellent surfaces can be created, or the wear-resistance of textile materials can be improved. Coatings incorporating nanoparticles as employed in sun creams protect sensitive polymers against decomposition due to ultraviolet radiation. Ballistic body wear based on fabrics protects against gun attacks but generally not against knives. For these products, thin coatings based on inorganic-organic hybrid polymers filled with alumina nanoparticles were found to give good stab-resistance. Further approaches deal e.g. with reversible photochromic coatings – coatings that change its color if irradiated with sun light -, (superpara-)magnetic hybrid polymers or medical systems based on porous sol-gel-coatings with immobilized drugs that are released in contact with skin. This paper will focus on approaches to improve ballistic body wear with respect to stab-resistance, UV-protection and water and oil repellence.

A simple sonochemical method has been employed for the surface functionalization of carbon nanotubes. Pristine single-walled carbon nanotubes (SWNTs) were irradiated by ultrasound in methyl methacrylate monomer. Polymer grafted carbon nanotubes were easily prepared by in situ sonochemically initiated radical polymerization of methyl methacrylate. FT-IR, TGA, SEM and TEM were used to characterize the polymethyl methacrylate (PMMA) grafted SWNTs. The surface-modified SWNTs afforded are then dispersible in good solvents for PMMA, such as dichloromethane and chloroform. The ‘green’ value involved in this simplifying processing contains low hazard, clean operation, reduced chemical consumption and short time, which undoubtedly generate profound impact on the development of carbon nanotube based nanochemistry and large scale nanotextiles application.

This paper describes our current work on electrical percolation in carbon nanotubes filled thermoplastic polymer fibers. The objective of this work is to develop an understanding of how the electrical properties of the nanotube/polymer composites are affected by processing conditions, orientation of nanotubes, and their loading fraction. In the first part of the work, mesoscale modelling of nanotubes was carried out using a dissipative particle dynamics method. The percolation threshold required to achieve an electrically conductive network of nanotubes within in a polymer fibre was predicted as a function of orientation and aspect ratio of nanotubes using a Monte Carlo method to measure the network impedance. In the second part of this work, X-ray diffraction analyses were carried out to find the degree of alignment of nanotubes in polyamide 12 fibers.