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Issues of fossil fuel and plastic pollution are shifting public demand toward biopolymer-based textiles. For instance, silk, which has been traditionally used during at least 5 milleniums in China, is re-emerging in research and industry with the development of high-tech spinning methods. Various arthropods, e.g. insects and arachnids, produce silky proteinic fiber of unique properties such as resistance, elasticity, stickiness and toughness, that show huge potential for biomaterial applications. Compared to synthetic analogs, silk presents advantages of low density, degradability and versatility. Electrospinning allows the creation of nonwoven mats whose pore size and structure show unprecedented characteristics at the nanometric scale, versus classical weaving methods or modern techniques such as melt blowing. Electrospinning has recently allowed to produce silk scaffolds, with applications in regenerative medicine, drug delivery, depollution and filtration. Here we review silk production by the spinning apparatus of the silkworm Bombyx mori and the spiders Aranea diadematus and Nephila Clavipes. We present the biotechnological procedures to get silk proteins, and the preparation of a spinning dope for electrospinning. We discuss silk’s mechanical properties in mats obtained from pure polymer dope and multi-composites. This review highlights the similarity between two very different yarn spinning techniques: biological and electrospinning processes.

Fish oil (FO) is a rich source of long-chain omega-3 polyunsaturated fatty acids (ω-3 LCPUFA) which are important for human health. This research investigated the fortification of chicken nuggets with encapsulated FO-Garlic essential oil (GEO) as a possible way for delivery of ω-3 LCPUFA. Five different chicken nugget samples were prepared according to different treatments: Control sample (without fish oil and encapsulated FO-GEO), bulk fish oil samples (0.4% and 0.8%, w/w), and encapsulated FO-GEO samples (4% and 8%, w/w). The quality of the chicken nugget samples were monitored during a 20-day refrigerated storage. Results showed that the addition of encapsulated FO-GEO could significantly delay lipid oxidation and microbiological spoilage of the samples during refrigerated storage. This is reflected by the pH, PV, TBARS and TVBN data (P

The Skin Model is modified with a frame in order to model the microclimate which is present between the skin and the clothing. The aim of the study is to design and instrument the system by allowing dynamic control of moisture management as a function of time. Resistive humidity sensors are placed at 4 locations in the frame to measure the transfer rate of water molecules through the fabric layer. After checking the reproducibility of measurement, the influence of physical parameters (weight, thickness, moisture regain and fabric design) and thermo-hydric characteristics of fabrics (air permeability, wetting time, one-way transport index, thermal resistance and water vapour permeability) on the transfer rate is analyzed by applying a multiple linear regression. The statistical analysis suggests that one of the main parameters significantly affecting the moisture management is the moisture regain of the fabrics related to its chemical composition, since high fabric moisture regain values lead to low water vapor transfer through the layer. Furthermore, the textile design (1×1 Interlock or jersey), wetting time (WT) and one-way transport index (R) have a low influence on these hydric transfers. To obtain further information, dynamic vapor sorption (DVS) and desiccant inverted cup methods are introduced. For the DVS, the maximum water sorption at 35 °C was determined by the mass difference between 0 and 98 % relative humidity (RH). The desiccant inverted cup method allows moisture transfer to be measured without forcing it unlike frame tests. Methods are compared and this investigation clearly demonstrates that DVS and frame test can be used to assess quantitatively the hygroscopicity, and the moisture transfer rate between the microclimate and the surrounding environment. These parameters are related to the interactive forces between fibers and water molecules, and the ability to store water molecules within fibers by increasing the sample mass.

In this study, a series of immiscible polymer blend fibers with polypropylene (PP) and polyvinyl alcohol (PVA) was obtained by a melt spinning process, and two different draw ratios were attempted. Efforts were made to obtain the porous PP fibers by removing the water-soluble PVA phase. The thermal properties of the blends were tested by thermogravimetric analysis and differential scanning calorimetry. The blends showed excellent thermal stability and differentiated fractionated crystallization behaviors of PP. The melt flow indexes of the blends were evaluated, exhibiting a higher fluidity than that of the neat polymers. Among the possible candidates for the spinning process, only the PP70–PVA30 had suitable spinnability, for which the draw ratio reached 3. The morphology of the fibers was investigated by selective extraction experiment and scanning electron microscopy, as well as wide-angle X-ray diffraction. The biphasic morphology and the crystallization behaviors varied according to the PVA content. Furthermore, the mechanical properties of the multifilament fibers were studied via tensile testing and dynamical mechanical analysis. The 70/30 weight ratio (PP/PVA) was the most suitable for producing biphasic fibers with a high degree of accessibility in PVA and mechanical properties that increase with the increase in the drawing ratio. The feasibility of fabric knitting was checked, and the mechanical properties and air permeability of the obtained textile structure were also evaluated.

This study focuses on the adoption of hybrid Janus kaolinite particles into immiscible PP–PVA blends for melt spinning, as an extension for the textile field. The anisotropic grafting of kaolinite ...

Poly(vinylidene fluoride) (PVDF)-electrosprayed nanofibers have been the subject of much research due to their flexibility and piezoelectric properties compared to other piezoelectrics, for example, ceramics or other polymeric materials. The piezoelectric performance of PVDF is mainly related to the presence of β-phase. This study aims to determine the influence of working and formulation parameters on the generation of β-phase, morphology, and crystal structure of PVDF nanofibers. In addition, this research innovatively analyzes the effect of the dispersion state of PVDF molecular chains in the solvent on the electrospinning results. The morphology and crystal structure of PVDF nanofibers were determined using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). Beadless nanofibers are obtained when the PVDF concentration reaches the semi-diluted regime entangled in dimethylformamide (DMF) or DMF/acetone solution. The optimization of the process parameters (static collector, tip to collector distance—25 cm, flow rate—1 mL/h, applied voltage—20 kV) allows the increase in the β-phase fraction from 68.3% ± 1.2% to 94.5% ± 0.6% for a PVDF concentration of 25 w/v% in a DMF/acetone mixture (2/3 v/v). With these same parameters applied to a rotating collector, it was observed that the piezoelectric performance is at maximum for a maximum β-phase fraction of 90.6% ± 1.1%, obtained for a rotational speed of 200 rpm. The effect of orientation of PVDF nanofibers on piezoelectric properties was quantitatively discussed for the first time; the piezoelectric properties are independent of the alignment of the nanofibers.

Polyvinylidene fluoride (PVDF) is among the most attractive piezo-polymers due to its excellent piezoelectricity, lightweight, flexibility, high thermal stability, and chemical resistance. PVDF can exist under different forms of films, membranes, and (nano)fibers, and its piezoelectric property related to its β phase content makes it interesting for energy harvesters and wearable applications. Research investigation shows that PVDF in the form of nanofibers prepared by electrospinning has more flexibility and better air permeability, which make them more suitable for these types of applications. Electrospinning is an efficient technique that produces PVDF nanofibers with a high β phase fraction and crystallinity by aligning molecular dipoles (–CH2 and –CF2) along an applied voltage direction. Different nanofibers production techniques and more precisely the electrospinning method for producing PVDF nanofibers with optimal electrospinning parameters are the key focuses of this paper. This review article highlights recent studies to summarize the influence of electrospinning parameters such as process (voltage, distance, flow rate, and collector), solution (Mw, concentration, and solvent), and ambient (humidity and temperature) parameters to enhance the piezoelectric properties of PVDF nanofibers. In addition, recent development regarding the effect of adding nanoparticles in the structure of nanofibers on the improvement of the β phase is reviewed. Finally, different methods of measuring piezoelectric properties of PVDF nanofibrous membrane are discussed.

Biobased lignin represents one of the possible materials for next-generation flame retardant additives due to its sustainability, environmental benefits and comparable efficiency to other flame retardant (FR) additives. In this context, this study presents the development of FR polyamide 11 (PA11) multifilament yarns and fabric structures containing different industrial lignins (i.e., lignosulfonate lignin (LL), and Kraft lignin (KL)) and zinc phosphinate (ZnP). The combination of ZnP and lignin (KL or LL) at different weight ratios were used to prepare flame retarded PA11 blends by melt mixing using a twin-screw extruder. These blends were transformed into continuous multifilament yarns by the melt-spinning process even at a high concentration of additives as 20 wt%. The mechanical test results showed that the combination of KL and ZnP achieved higher strength and filaments showed regularity in structure as compared to the LL and ZnP filaments. Thermogravimetric (TG) analysis showed the incorporation of lignin induces the initial decomposition (T5%) at a lower temperature, at the same time, maximum decomposition (Tmax) shifts to a higher temperature region and a higher amount of char residue is reported at the end of the test. Further, the TGA-FTIR study revealed that the ternary blends (i.e., the combination of LL or KL, ZnP, and PA11) released mainly the phosphinate compound, hydrocarbon species, and a small amount of phosphinic acid during the initial decomposition stage (T5%), while hydrocarbons, carbonyls, and phenolic compounds along with CO2 are released during main decomposition stage (Tmax). The analysis of decomposition products suggests the stronger bonds formation in the condensed phase and the obtainment of a stable char layer. Cone calorimetry exploited to study the fire behavior on sheet samples (polymer bulk) showed an improvement in flame retardant properties with increasing lignin content in blends and most enhanced results were found when 10 wt% of LL and ZnP were combined such as a reduction in heat release rate (HRR) up to 64% and total heat release (THR) up to 22%. Besides, tests carried out on knitted fabric structure showed less influence on HRR and THR but the noticeable effect on postponing the time to ignition (TTI) and reduction in the maximum average rate of heat emission (MARHE) value during combustion.

Electrospraying is considered to be a green, high-efficiency method for synthesizing phase change microcapsules (mPCMs) for possible applications in the fields of energy storage and thermal regulation. In this study, a coaxial nozzle was used to prepare n-hexadecane/polycaprolactone (PCL) microparticles. The objectives of this study were to investigate the influence of working parameters and solutions on morphology, particle size, thermal properties and encapsulation efficiency. Thus, three theoretical loading contents in n-hexadecane (30%, 50% and 70% w/w) and two concentrations of PCL (5 and 10% w/v) were used. The structures, morphologies and thermal properties of mPCMs were characterized by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). Spherical microcapsules with a mean diameter of 10&ndash, 20 &micro, m were prepared. The increased concentration of n-hexadecane and PCL resulted in a change in the particle size distribution from a poly-disperse to monodisperse size distribution and in a change in the surface state from porous to non-porous. In addition, higher encapsulation efficiency (96%) and loading content (67%) were achieved by the coaxial nozzle using the high core-shell ratio (70/30) and 10% w/v of PCL. The latent heat of the mPCMs reached about 134 J.g&minus, 1. In addition, it was also observed that the thermal stability was improved by using a coaxial system rather than a single nozzle.

In this study, the sorption and desorption isotherms from the dynamic vapor sorption test are modeled by using six different models, that is, the (i) BET (Brunauer–Emmett–Teller), (ii) modified BET, (iii) GAB (Guggenheim–Anderson–Boer), (iv) PEK (parallel exponential kinetics), (v) HH (Hailwood–Horrobin), and (vi) Nelson and Young models. The application principle of each model is explained and a comparison is done between these models, based on the understanding of sorption mechanisms on or into the textile substrates. They mainly depend on the chemical nature of the fibers used to manufacture the samples. Thus, the presence of various sorption/desorption sites on the surface and/or in the inner core of hydrophilic materials promotes the formation of more hydrogen bonds with water vapor molecules than for hydrophobic materials. Among these previous used models, the PEK, HH, and Nelson and Young models were studied to analyze the water molecule diffusion into the structures, while the GAB and BET models were selected to gain information on the water uptaken as the monolayer and energies of interactions between fibers and water molecules. By understanding the hydric behavior of fabrics during sorption/desorption processes, the fiber blends can be modified for improving the wearer comfort.

This study investigates the thermal decomposition and fire behavior of zinc phosphinate (ZnP) in combination with low sulphonate content alkali lignin (LS) in a polyamide 11 (PA11) matrix. The influence of ZnP with LS on PA11 was assessed by using thermogravimetric analysis coupled with FTIR spectroscopy (TG-FTIR). Such decomposition products as hydrocarbons, amide and carbonyl units, phenolic and phosphinate compounds control the decomposition. The chemical structure of the condensed phase was evaluated by FTIR measurements carried out on the residues. The fire behavior was investigated using UL 94 vertical flame spread tests and cone calorimetry tests. In the ternary blends, the addition of LS promotes char formation as assessed by TG analyses; furthermore, ZnP contributes to flame inhibition mainly by radical trapping and partially by dilution of fuel, due to phosphinate ions and a small amount of phosphinic acid released in the gas phase. Besides, phosphate compounds are formed in the condensed phase. The combination of LS and ZnP enhanced flame-retardant properties due to the formation of a stable char layer with barrier features.

The behavior of aqueous chitosan (CH), type-B gelatin (GB) and CH-GB coacervate was studied on oil-in-water emulsion formulation at various pH and concentration ratio. The coacervate was formed by phase separation at ratios CH:GB, 1:10 to 1:1 with total biopolymer concentrations of 0.55%-1.0% (w/v) at pH 4.0-5.5. Soluble complexes were formed below pH 5.0 and coacervate formation was confirmed at pH 5.0 and above by zeta potential and UV-spectroscopy measurements. The coacervate formation was found maximum at the CH-GB ratios of 1:10 and 1:5 at pH 5.5. Formulated emulsions (>10μm droplets) using 1% (w/v) chitosan and GB were found stable (+52.5mv and creaming index 86%) and unstable respectively. Emulsion stabilized by mixed CH:GB 1:5 (3%w/v) had no creaming effect. The instability was attributed to the lower surface activity (K=5.0Lg-1) of pure GB compared to CH (K=14.3Lg-1). The formulation and methods can successfully tune the stability of the emulsions.

Zinc phosphinate (Exolit OP950), nanosilica particles and polyethylene terephthalate (PET) have been blended and thereafter melt-spinned to develop a new flame retardant (FR) system for PET textiles. The effects of the two types of nanosilica fillers on the wettability, dispersibility and thermal properties were studied to determine how the degree of hydrophilicity affects the PET matrix. The influence of the blends on thermal transitions has been investigated by differential scanning calorimetry (DSC), the thermal stability of the polymer/FR blend composites has been assessed by thermogravimetric analysis (TGA) and cone calorimetry has been used to study the fire reaction. It was noticed that the nanoparticles have a limited influence on the thermal transitions of the PET matrix, but zinc phosphinate acted as a plasticizer and a compatibilizer for the more hydrophobic particles. Thermogravimetric analysis results showed that the addition of silica particles and FR compound improves slightly the thermal stability of the PET systems under nitrogen and air atmospheres. Furthermore, it was noticed that the incorporation of nanoparticles gives almost no improvement in the PET fire reaction from cone calorimeter experiments. However, in the presence of Exolit OP950, the systems acted as FR in PET films and knitted structures. The heat release rate during the combustion decreased, and the thermal behaviors of these structures were closed to those with 10% wt of Exolit OP950. Copyright © 2017 John Wiley & Sons, Ltd.

The phase change microcapsule (mPCM) is one of the primary candidates in the fields of energy storage and thermal regulation. In this study, electro-spraying, as a green, high-efficiency electrohydrodynamic atomization technology, is applied to the microencapsulation of two phase change materials (PCM) (n-hexadecane and n-eicosane) with three loading contents (30%, 50%, and 70% by weight) in a polycaprolactone matrix. Ethyl acetate (EA) and chloroform (Chl) were chosen as solvents to prepare the working solutions. The objective of this study is to clarify the microencapsulation process during electro-spraying and to optimize the structure and properties of the electro-sprayed mPCM. The structures, morphologies, and thermal properties of the mPCM were characterized by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), and fourier transform infrared spectroscopy (FT-IR). Electro-sprayed spherical and non-porous mPCM have been successfully prepared. The mean diameter and the particle size distribution depend mainly on the choice of the n-alkane, as well as the solvent used to prepare the working solutions. Meanwhile, the structure formation of electro-sprayed mPCM and the loading content of PCM were mainly influenced by the evaporation of the solvent and the phase separation between PCM and poly(caprolactone) (PCL) matrix. During the shell formation or PCL solidification, the control of the PCM leaching out of the matrix allows improving the loading content. Finally, based on a high latent heat and simple formation process, the electro-spraying route of PCM is a green, non-toxic, and high-efficiency direction for energy storage and heat regulation.

In the field of pharmaceutical technology, significant attention has been paid on exploiting skin as a drug administration route. Considering the structural and chemical complexity of the skin barrier, many research works focused on developing an innovative way to enhance skin drug permeation. In this context, a new class of materials called bio-functional textiles has been developed. Such materials consist of the combination of advanced pharmaceutical carriers with textile materials. Therefore, they own the possibility of providing a wearable platform for continuous and controlled drug release. Notwithstanding the great potential of these materials, their large-scale application still faces some challenges. The present review provides a state-of-the-art perspective on the bio-functional textile technology analyzing the several issues involved. Firstly, the skin physiology, together with the dermatological delivery strategy, is keenly described in order to provide an overview of the problems tackled by bio-functional textiles technology. Secondly, an overview of the main dermatological nanocarriers is provided; thereafter the application of these nanomaterial to textiles is presented. Finally, the bio-functional textile technology is framed in the context of the different dermatological administration strategies; a comparative analysis that also considers how pharmaceutical regulation is conducted.

Flame retardancy of polymers is a recurring obligation for many applications. The development trend of biobased materials is no exception to this rule, and solutions of flame retardants from agro-resources give an advantage. Lignin is produced as a waste by-product from some industries, and can be used in the intumescent formation development as a source of carbon combined with an acid source. In this study, the flame retardancy of polyamide 11 (PA) is carried out by extrusion with a kraft lignin (KL) and ammonium polyphosphate (AP). The study of the optimal ratio between the KL and the AP makes it possible to optimize the fire properties as well as to reduce the cost and facilitates the implementation of the blend by a melting process. The properties of thermal decomposition and the fire reaction have been studied by thermogravimetric analyzes, pyrolysis combustion flow calorimetry (PCFC) and vertical flame spread tests (UL94). KL permits a charring effect delaying thermal degradation and decreases by 66% the peak of heat release rate in comparison with raw PA. The fire reaction of the ternary blends is improved even if KL-AP association does not have a synergy effect. The 25/75 and 33/67 KL/AP ratios in PA give an intumescence behavior under flame exposure.

A series of thermosensitive films for firefighting applications were synthesized by two-step polymerization from two types of polyol and isophorone diisocyanate and by the formation of aqueous polyurethane dispersions. This study was conducted to clarify the influence of different parameters such as the type of polyol, the chain length of polyol, and the hard segment content on the chemical, thermal, mechanical and diffusion properties of the final films using ATR infrared spectroscopy, differential scanning calorimetry, thermogravimetric analyses, water vapor permeability, swelling behavior, contact angle measurement, and dynamic mechanical analyses. It was noticed that the humidity transfer was influenced by the soft segment crystallization. Indeed, it enhanced the chain mobility in bulk materials leading to an increase in water vapor permeability rather than in swelling. In contrast, low crystallization induced surface state modification resulting in higher swelling capacity.

This study focuses on the influence of electrospinning processes on the properties of electrospun fibres. We have optimised the parameters: distance, voltage, concentration of electrospinning to analyse the influence of these parameters on the properties, in particular the structure and morphology of the nano-fibres. The mass of the required polyamide was measured using an analytical balance and dissolved in formic acid to obtain a homogeneous mixture. The solution was stirred for 24 hours and then cooled and inserted into the syringe to be electro-threaded. The concentration of the solution played a decisive role during the spinning process and influenced in particular the determination of the diameter but also the morphology of the nanofibres. A concentration of 15% PA-6 and a low viscosity solution of 266 mPa allowed us to obtain higher quality fibres. The results obtained by the SEM show that the increase in the electric field causes the fibre diameter to increase from 170nm to 234nm. The structures, nano-fibre morphologies and thermal properties of PA-6 have been characterised using scanning electron microscopy (SEM), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). Defect-free fibres with extremely small diameters and a large specific surface area were produced. Which we will use to manufacture photo deformable textiles. After spinning the flawless fibres, we can continue this study in the near future by adding a fire retardant active ingredient to the polyamide solution, to improve the resistance of the fibres and their morphology.

Electrosprayed poly(caprolactone) (PCL) microparticles were produced using five solvents (ethyl acetate, acetone, anisole, glacial acetic acid and chloroform) under different PCL concentrations and operating parameters. Not only green and appropriate solvent for PCL electrospraying was pointed out, but also the effects of solution properties (surface tension, electrical conductivity, viscosity and vapor pressure) and operating parameters (flow rate, working distance and applied voltage) on the formation of electrosprayed particles were clarified. The formation and shape of Taylor cone during electrospraying was observed by high-speed images captured with a camera, and the size and morphology of electrosprayed particles were characterized by optical and scanning electron microscopies. It can conclude that the cone&ndash, jet range of applied voltage mainly depended on electrical conductivity, and an ideal Taylor cone was easier to form under high viscosity and low surface tension. Although high electrical conductivity was a contributor to fabricate tiny particles, it was easier to fabricate mono-dispersed microparticles under low electrical conductivity. The poly-dispersed distribution obtained with a high electrical conductivity converted into mono-dispersed distribution with the increasing of viscosity. Furthermore, the size of electrosprayed particles also correlated with the surface tension and vapor pressure of the solvent used. Ethyl acetate, due to mild electrical conductivity and surface tension, moderate viscosity and vapor pressure, is a green and suitable solvent for PCL electrospraying. Single pore PCL microparticles with smooth cherry-like morphology can be prepared from ethyl acetate. Finally, long working distance not only stabilizes the break-up of charged jet, but also promotes the evaporation of solvent.

In this study, two different types of industrial lignin (i.e., lignosulphonate lignin (LL) and kraft lignin (DL)) were exploited as charring agents with phosphorus-based flame retardants for polyamide 11 (PA11). The effect of lignins on the thermal stability and fire behavior of PA11 combined with phosphinate additives (namely, aluminum phosphinate (AlP) and zinc phosphinate (ZnP)) has been studied by thermogravimetric analysis (TGA), UL 94 vertical flame spread, and cone calorimetry tests. Various blends of flame retarded PA11 were prepared by melt process using a twin-screw extruder. Thermogravimetric analyses showed that the LL containing ternary blends are able to provide higher thermal stability, as well as a developed char residue. The decomposition of the phosphinates led to the formation of phosphate compounds in the condensed phase, which promotes the formation of a stable char. Flammability tests showed that LL/ZnP ternary blends were able to achieve self-extinction and V-1 classification, the other formulations showed a strong melt dripping and higher burning. In addition to this, cone calorimetry results showed that the most enhanced behavior was found when 10 wt % of LL and AlP were combined, which strongly reduced PHRR (&minus, 74%) and THR (&minus, 22%), due to the interaction between LL and AlP, which not only promotes char formation but also confers the stability to char in the condensed phase.

In recent years, the textile industry has been moving to novel concepts of products, which could deliver to the user, improved performances. Such smart textiles have been proven to have the potential to integrate within a commodity garment advanced feature and functional properties of different kinds. Among those functionalities, considerable interest has been played in functionalizing commodity garments in order to make them positively interact with the human body and therefore being beneficial to the user health. This kind of functionalization generally exploits biopolymers, a class of materials that possess peculiar properties such as biocompatibility and biodegradability that make them suitable for bio-functional textile production. In the context of biopolymer chitosan has been proved to be an excellent potential candidate for this kind of application given its abundant availability and its chemical properties that it positively interacts with biological tissue. Notwithstanding the high potential of chitosan-based technologies in the textile sectors, several issues limit the large-scale production of such innovative garments. In facts the morphologies of chitosan structures should be optimized in order to make them better exploit the biological activity; moreover a suitable process for the application of chitosan structures to the textile must be designed. The application process should indeed not only allow an effective and durable fixation of chitosan to textile but also comply with environmental rules concerning pollution emission and utilization of harmful substances.

The textile industry has recently been developing innovative products that integrate functional properties within commodity textiles. In particular, research has focussed on the concept of biofunctional textiles, i.e., textile materials possessing beneficial properties for human health. Biofunctional textiles are synthesised by functionalization of fabric surfaces with biopolymers. As an example, the chitosan biopolymer is promising for textile functionalization due to chitosan availability, low cost, safety and unique properties. Yet several challenges have to be overcome. Firstly, the morphology of chitosan must be optimized prior chitosan application to the textile surface. Secondly, the last treatment must be carefully designed in order to achieve an effective and durable functionalization. Lastly, the overall production process must comply with environmental rules concerning pollution emission and utilization of harmful substances. This review describes microencapsulation as a strategy to overcome limitations and to confer better properties to the textile material. The properties of chitosan and the concept of microencapsulation are presented. Then we present the main techniques of chitosan encapsulation. Furthermore, we detail the textile finishing processes and the textile products. Last, the perspectives are discussed in the context of green chemistry and compliance with an environmentally friendly approach.

Flash nanoprecipitation (FNP) is a widely used technique to prepare particulate carriers based on various polymers, and it was proven to be a promising technology for the industrial production of drug loaded nanoparticles. However, up to now, only its application to hydrophobic compounds has been deeply studied and the encapsulation of some strongly hydrophilic compounds, such as caffeine, remains a challenge. Caffeine loaded poly-&epsilon, caprolactone (PCL) nanoparticles were produced in a confined impinging jet mixer using acetone as the solvent and water as the antisolvent. Caffeine was dissolved either in acetone or in water to assess the effects of two different process conditions. Nanoparticles properties were assessed in terms of loading capacity (LC%), encapsulation efficiency (EE%), and in vitro release kinetics. Samples were further characterized by dynamic light scattering, scanning electron microscopy, X-ray photo electron spectroscopy, and infrared spectroscopy to determine the size, morphology, and structure of nanoparticles. FNP was proved an effective technique for entrapping caffeine in PCL and to control its release behavior. The solvent used to solubilize caffeine influences the final structure of the obtained particles. It was observed that the active principle was preferentially adsorbed at the surface when using acetone, while with water, it was embedded in the matrix structure. The present research highlights the possibility of extending the range of applications of FNP to hydrophilic molecules.

Sol–gel polycondensation was used to encapsulate two different kinds of core with a silica shell, i.e. castor oil which is considered as a model active agent, and bisphenol A bis(diphenyl phosphate), an insoluble liquid fire retardant. The influence of the nature of the emulsifier was also studied, i.e. Pickering emulsion based on the interface stabilization performed by the organization of solid nanoparticles was compared to a classical emulsion process using a non-ionic surfactant. The influence of both cores and emulsifiers on the stability of emulsion was studied by granulometric analysis, optical microscopy and macroscopic morphology (from nacked-eye observations). The sol–gel encapsulation efficiency was assessed by Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analysis. Finally, thermal stability of microcapsules was evaluated by thermogravimetric analysis (TGA). Results show that both Pickering and classical emulsions processing allow successful sol–gel encapsulation of castor oil and bisphenol A bis (diphenyl phosphate) with a satisfying thermal stability for textile application. However, the use of Pickering emulsion with nanoparticles provides more highly stable emulsions and promotes silica shell formation.

A series of chitosan/gelatin based microcapsules containing n-hexadecane was synthesized through complex phase coacervation from chitosan (CH) and type-B gelatin (GB), and crosslinked by glutaraldehyde (GTA). This research was conducted to clarify the influence of different parameters on the encapsulation process, i.e., the emulsion formation and the shell formation, using zeta potential and surface tension measurements, attenuated total reflectance (ATR), and thermal analysis such as differential scanning calorimetry (DSC). The optimal values of biopolymer ratios (TBP), crosslinker amount, emulsion time and feeding weight ratio of core/shell polymer (RCS) were identified. The stability of the emulsion was depended on the surface activity and TBP ratio, which also affected the droplet size distribution and the thickness of the shell. Furthermore, core content, encapsulation efficiency and thermal properties of the microcapsules were related to TBP and RCS; with the lowest RCS giving the best microcapsules features.

In recent years transdermal drug delivery has aroused significant interest as a sustained and non-invasive way of administering active substances. The advancements of nanotechnology allowed the development of novel pharmaceutical formulations overcoming skin barrier. Furthermore, such nano-system can be combined with conventional fabrics to pave the way to a new generation of wearable drug delivery devices: bio-functional garments. First the NP were produced by flash nanoprecipitation technique (FNP), the production process was optimized to produce particles with suitable size for transdermal applications. The nanoparticles were characterized in terms of drug content by UV-visible spectroscopy and in term of antioxidant activity by Electron Paramagnetic Resonance spectroscopy (EPR) coupled with spin trapping technique. The NPs were used to functionalize cotton and viscose-micromodal fabrics and the transdermal release properties were tested in vitro by Franz's Cell experiment. FNP was proven to be an effective technique to produce tunable size particles. Moreover, the nanoencapsulated drug exhibited antioxidant activity. The Franz's Cell test evidenced a controlled release behavior, providing evidence that the bio-functional textile is suitable for applications where sustained release and antioxidant properties are required.

Linseed oil which has various biomedical applications was encapsulated by chitosan (Chi)-based microcapsules in the development of a suitable carrier. Oil droplets formed in oil-in-water emulsion using sodium dodecyl sulfate (SDS) as emulsifier was stabilized by Chi, and microcapsules with multilayers were formed by alternate additions of SDS and Chi solutions in an emulsion through electrostatic interaction. No chemical cross-linker was used in the study and the multilayer shell membrane was formed by ionic gelation using Chi and SDS. The rigidification of the shell membrane of microcapsules was achieved by alkali treatment in the presence of a small amount of 1-butanol to reduce aggregation. A trisodium citrate solution was used to stabilize the charge of microcapsules by ionic cross-linking. Effects of butanol during alkali treatment and citrate in post alkali treatment were monitored in terms of morphology and the chemical properties of microcapsules. Various characterization techniques revealed that the aggregation was decreased and surface roughness was increased with layer formation.

The present study describes the development of multilayer microcapsules by 11 alternate additions of chitosan (Chi) and sodium dodecyl sulfate (SDS) in a combined emulsification and phase coacervation method based on ionic interactions. After an alkali treatment, microcapsules are applied on polyester (PET) fabric by a padding process to investigate their wash-durability on fabric. Air atmospheric plasma treatment is performed on PET fabric to modify the surface properties of the textiles. Zeta potential, X-ray photoelectron spectroscopy (XPS), wetting measurements, scanning electron microscopy (SEM), and atomic force microscopy (AFM) with surface roughness measurements are realized to characterize and determine wash durability of microcapsule samples onto PET. After alkali treatment, the microcapsules are selected for textile application because they are submicron sized with the desired morphology. The results obtained from various characterization techniques indicate that microcapsules are wash-durable on PET fabric pre activated by air plasma atmospheric as Chi based microcapsules can interact directly with PET by ionic interactions.

The present study focused on formation of chitosan (CS) droplets particles/microcapsules by ionic gelation method with sodium dodecylsulfate (SDS) for encapsulating linseed oil as active substance. Chitosan droplet particles with four alternate layers of CS and SDS were developed from oil in water emulsion using SDS as an anionic emulsifier. The process was optimized by zeta potential measurements to avoid overcharging of particles by excess addition of CS. The drying process promoted coalescence of CS droplet particles to form a functional coating and to protect the core substance against influence of environmental conditions. The functional coating formed by the particles was characterized by scanning electron microscopy, wetting measurements, and atomic force microscopy and surface roughness. Atomic force microscopy and surface roughness analyses indicated that smooth surface with more hydrophobic groups on the surface of functional coating was obtained after CS addition and it was due to film forming ability of CS chains in the system.

This study investigated nano-encapsulation of fish oil (FO) and garlic (Allium sativum L.) essential oil (GEO) using Persian gum (PG) and chitosan (Chi) as wall materials (at the ratio of 2:1, 1:1 and 1:2 (w/w) and core/wall ratio of 10:2 (w/w)), applying the electrostatic layer-by-layer deposition method. Our findings revealed that PG:Chi 2:1 ratio was the best combination of wall material, giving good zeta potential (33.4 ± 1.6 mV), maximum emulsion stability, surface tension (56 ± 0.3 mN m−1) and viscosity (1.09 ± 0.04 Pa s) while maintaining minimum droplet size (23.19 nm) and PDI (0.120 ± 0.002). Consistent with the emulsion studies, the PG:Chi 2:1 ratio gave nano-capsules with the best reconstituted emulsion properties. This includes zeta potential of 34±1 mV, droplet size in nano range (mean size, 65 nm) with good stability and low dispersibility (PDI, 0.385 ± 0.004). From scanning electron microscopy (SEM), the FO-GEO nano-capsules show agglomerated morphology with spherical particles. The success of FO-GEO encapsulation was confirmed by the results obtained from differential scanning calorimetry (DSC), X-Ray Diffraction (XRD) and Fourier-Transform Infrared Spectroscopy (FTIR) analyses. The physicochemical characteristics and thermal stability indicated that such nano-capsules have promising use in pharmaceutical and food industries for delivery of FO-GEO.