Zeeshan Khatri

Cationic-cellulose nanofibers: preparation and dyeability with anionic reactive dyes for apparel application.

Continuous effort in research and development of nanofibers for apparel usage has been focused within their functional properties only. We investigated esthetic properties by producing colored cationic-cellulose nanofibers for the very first time for the potential application of apparel use. The cellulose acetate nanofibers were electrospun followed by deacetylation and cationization to produce functional cationic-cellulose nanofibers and then dyed with anionic reactive dyes. The spectrophotometric measurement of dyed samples was carried out to determine color coordinates and color yield values. The cationic-cellulose nanofibers showed enhanced color yield and dye fixation without addition of an electrolyte in comparison to cellulose nanofibers. The cationization of cellulose nanofibers significantly enhanced the color yield values of around 76% at dye concentrations of 5%. Excellent color fastness results demonstrate that these new colored and breathable materials can potentially be considered as future apparel for casual or fashion.

Cold Pad-Batch dyeing method for cotton fabric dyeing with reactive dyes using ultrasonic energy

Reactive dyes are vastly used in dyeing and printing of cotton fibre. These dyes have a distinctive reactive nature due to active groups which form covalent bonds with -OH groups of cotton through substitution and/or addition mechanism. Among many methods used for dyeing cotton with reactive dyes, the Cold Pad Batch (CPB) method is relatively more environment friendly due to high dye fixation and non requirement of thermal energy. The dyed fabric production rate is low due to requirement of at least twelve hours batching time for dye fixation. The proposed CPB method for dyeing cotton involves ultrasonic energy resulting into a one third decrease in batching time. The dyeing of cotton fibre was carried out with CI reactive red 195 and CI reactive black 5 by conventional and ultrasonic (US) method. The study showed that the use of ultrasonic energy not only shortens the batching time but the alkalis concentrations can considerably be reduced. In this case, the colour strength (K/S) and dye fixation (%F) also enhances without any adverse effect on colour fastness of the dyed fabric. The appearance of dyed fibre surface using scanning electron microscope (SEM) showed relative straightening of fibre convolutions and significant swelling of the fibre upon ultrasonic application. The total colour difference values ΔE (CMC) for the proposed method, were found within close proximity to the conventionally dyed sample.

Antibacterial property and characterization of cotton fabric treated with chitosan/AgCl-TiO2 colloid

The antibacterial activity of cotton fabric was studied by using chitosan/AgCl-TiO2 colloid. Different blend ratios of chitosan to AgCl-TiO2 colloid were used to investigate the efficacy of antibacterial activity against Staphylococcus aureus (gram positive) and Escherichia coli (gram negative) and its effect on physical properties of cotton fabric. Our study shows that the combination of chitosan with AgCl-TiO2 colloid produced better antibacterial activity than the fabric treated without chitosan; 100% bacterial reduction against S. aureus and E. coli obtained with chitosan/AgCl-TiO2 colloid at concentrations of 4 g/L and 10 g/L respectively. Moreover, the treated cotton indicates improved tensile strength and wrinkle recovery angle (WRA). Increasing chitosan concentration slightly affected the fabric stiffness and whiteness. The treated cotton fabrics were further characterized by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), energy dispersive X-ray (EDX) and wide angle X-ray (WAXD). We can expect a direct industrial application of our proposed work because it is simple one go pad-dry-cure method and the low cost commercial grades of chitosan and AgCl-TiO2 are conveniently available in the market.

Zein/cellulose acetate hybrid nanofibers: Electrospinning and characterization

Protein based scaffolds are preferred for tissue engineering and other biomedical applications owing to their unique properties. Zein, a hydrophobic protein, is a promising natural biodegradable polymer. However, electrospun structures prepared from Zein have poor mechanical and wetting properties. Cellulose acetate (CA) is an economical, biodegradable polymer having good mechanical and water retention properties. The aim of present study was to fabricate a novel material by electrospinning Zein/CA blends. A series of Zein/CA hybrid nanofibers were electrospun and characterized. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATRFTIR) spectrum showed the characteristic peaks of both Zein and CA, and was composition dependent. The X-ray photoelectron spectrometry (XPS) curves of Zein/CA blends demonstrated a similar profile to that of pristine Zein nanofibers. Thermogravimetric analyser (TGA) studies confirmed that the Zein/CA hybrid nanofibers have a higher degradation temperature and better thermal stability than pristine Zein nanofibers. The glass transition temperature (Tg) of Zein/CA hybrid nanofibers was also increased in comparison to pure Zein nanofibers as revealed by differential scanning calorimetry (DSC). Zein/CA hybrid nanofibers have hydrophilic surface character as revealed by water contact angle (WCA) analysis. SEM imaging showed bead free morphology of the electrospun nanofibers. The average nanofiber diameter decreased for Zein/CA blends with increasing CA composition. The electrospun Zein/CA hybrid nanofibers may be used for tissue engineering scaffolds and for other biomedical materials.

Co-electrospun poly(ɛ-caprolactone)/cellulose nanofibers-fabrication and characterization

We report fabrication of poly (ɛ-caprolactone) (PCL)/cellulose (CEL) nanofiber blends via co-electrospinning for the possible use as biofilters and biosensor strips. Five different ratios of PCL to CEL were fabricated to investigate the wicking behavior. The cellulose acetate (CA) was taken as precursor to make cellulose nanofibers. Double nozzles were employed for jetting constituent polymers toward collector drum independently and resultant nanofibers webs were deacetylated in aqueous alkaline solution to convert CA into CEL as confirmed by FTIR spectra. FTIR further revealed that there is no effect of deacetylation on PCL nanofiber. The morphology of each blend webs under SEM showed uniform and bead-free nanofibers. Wicking behavior for five different ratios of PCL/CEL suggested that increasing CEL ratio in the blend enhanced the wicking front height; however, X-ray diffraction patterns of PCL/CEL showed a slight decrease in crystallinity.

Ultrasonic dyeing of cellulose nanofibers.

Textile dyeing assisted by ultrasonic energy has attained a greater interest in recent years. We report ultrasonic dyeing of nanofibers for the very first time. We chose cellulose nanofibers and dyed with two reactive dyes, CI reactive black 5 and CI reactive red 195. The cellulose nanofibers were prepared by electrospinning of cellulose acetate (CA) followed by deacetylation. The FTIR results confirmed complete conversion of CA into cellulose nanofibers. Dyeing parameters optimized were dyeing temperature, dyeing time and dye concentrations for each class of the dye used. Results revealed that the ultrasonic dyeing produced higher color yield (K/S values) than the conventional dyeing. The color fastness test results depicted good dye fixation. SEM analysis evidenced that ultrasonic energy during dyeing do not affect surface morphology of nanofibers. The results conclude successful dyeing of cellulose nanofibers using ultrasonic energy with better color yield and color fastness results than conventional dyeing.

Photodegradation of dyes by a novel TiO2/u-RuO2/GNS nanocatalyst derived from Ru/GNS after its use as a catalyst in the aerial oxidation of primary alcohols (GNS = graphene nanosheets)

Ruthenium nanoparticles (RuNPs) supported on graphene nanosheets (GNS), a composite (Ru/GNS), were prepared by a dry synthesis method and were used as nanocatalysts for the aerial oxidation of various primary alcohols. Ru/GNS was highly efficient, selective, stable and heterogeneous in nature. Owing to the high stability of the used catalyst (u-Ru/GNS), it was further applied in a different catalytic system viz photocatalytic degradation, after suitable modifications. We have obtained a novel TiO2/u-RuO2/GNS catalyst from u-Ru/GNS by the sol-gel method. The catalytic activity of TiO2/u-RuO2/GNS toward the photodegradation of methyl orange (MO) and acridine orange (AO) was found to be excellent. Overall, the sustainable use of these recyclable materials (Ru/GNS and TiO2/u-RuO2/GNS) could lead to economic and environmental benefits.

Ultrasonic-assisted deacetylation of cellulose acetate nanofibers: A rapid method to produce cellulose nanofibers.

Herein we report a rapid method for deacetylation of cellulose acetate (CA) nanofibers in order to produce cellulose nanofibers using ultrasonic energy. The CA nanofibers were fabricated via electrospinning thereby treated with NaOH and NaOH/EtOH solutions at various pH levels for 30, 60 and 90min assisted by ultrasonic energy. The nanofiber webs were optimized by degree of deacetylation (DD%) and wicking behavior. The resultant nanofibers were further characterized by FTIR, SEM, WAXD, DSC analysis. The DD% and FTIR results confirmed a complete conversion of CA nanofibers to cellulose nanofibers within 1h with substantial increase of wicking height. Nanofibers morphology under SEM showed slightly swelling and no damage of nanofibers observed by use of ultrasonic energy. The results of ultrasonic-assisted deacetylation are comparable with the conventional deacetylation. Our rapid method offers substantially reduced deacetylation time from 30h to just 1h, thanks to the ultrasonic energy.

Preparation and characterization of hybrid polycaprolactone/cellulose ultrafine fibers via electrospinning

A series of poly(ɛ-caprolactone) (PCL)/cellulose acetate (CA) ultrafine fiber webs were prepared via electrospinning followed by deacetylation in an aqueous alkaline solution to convert CA into cellulose (CEL). The wetting properties of PCL/CA and PCL/CEL blends were evaluated to investigate wicking behavior. The results showed that the conversion of PCL/CA into PCL/CEL leads to an improved wettability. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) study revealed that CA was completely converted into CEL after deacetylation, and PCL/CEL blends exhibited characteristics peaks of both constituent fibers. The differential scanning calorimetry (DSC) analysis demonstrated that the PCL/CA ultrafine fibers were partially miscible in PCL/CA ultrafine fibers. The fiber morphology under field emission scanning electron microscopy (FE-SEM) showed that the electrospun ultrafine fibers were bead free. The crystallinity of PCL-CEL, (1:4) blend was greatly decreased in comparison to the treated PCL as revealed by wide angle X-ray diffraction (WAXD) measurements. The potential applications of PCL/CEL webs include liquid biofilters, biosensor and biomedical materials.

Antibacterial efficacy of poly(vinyl alcohol) composite nanofibers embedded with silver-anchored silica nanoparticles

Silver has been widely used as an effective antibacterial agent especially for treating burns and wounds. However, release of silver from materials often arouse side effects due to toxicity of silver towards mammalian cells. Argyria and argyrosis are well known problems of acute toxicity of silver towards human body. Immobilization of silver is an effective approach to reduce silver release. Herein, we present poly(vinyl alcohol) (PVA) composite nanofibers embedded with silver-anchored silica nanoparticles (SSNs) as a novel antibacterial material. Silver nanoparticles anchored on silica nanoparticles were prepared and incorporated into PVA nanofibers to fabricate silver-silica embedded PVA nanofibers (SSN-PVA) by electrospinning. Incorporation of SSNs into PVA was confirmed by TEM and SEM results revealed regular nanofibers whose diameter increased with successive addition of SSNs. The SSN-PVA nanofibers showed significant antibacterial efficacy against both Gram-negative and Gram-positive bacteria. Our research results demonstrated SSN-embedded polymeric nanofibers can open up a promising prospect for the prevention of bacterial infection in diverse biomedical fields including wound dressing.