Nano-Structured Ridged Micro-Filaments (≥100 µm Diameter) Produced Using a Single Step Strategy for Improved Bone Cell Adhesion and Proliferation in Textile Scaffolds.

Textile scaffolds that are either 2D or 3D with tunable shapes and pore sizes can be made through textile processing (weaving, knitting, braiding, nonwovens) using microfilaments. However, these filaments lack nano-topographical features to improve bone cell adhesion and proliferation. Moreover, the diameter of such filaments should be higher than that used for classical textiles (10−30 µm) to enable adhesion and the efficient spreading of the osteoblast cell (>30 µm diameter). We report, for the first time, the fabrication of biodegradable nanostructured cylindrical PLLA (poly-L-Lactic acid) microfilaments of diameters 100 µm and 230 µm, using a single step melt-spinning process for straightforward integration of nano-scale ridge-like structures oriented in the fiber length direction. Appropriate drawing speed and temperature used during the filament spinning allowed for the creation of instabilities giving rise to nanofibrillar ridges, as observed by AFM (Atomic Force Microscopy). These micro-filaments were hydrophobic, and had reduced crystallinity and mechanical strength, but could still be processed into 2D/3D textile scaffolds of various shapes. Biological tests carried out on the woven scaffolds made from these nano-structured micro filaments showed excellent human bone cell MG 63 adhesion and proliferation, better than on smooth 30 µm- diameter fibers. Elongated filopodia of the osteoblast, intimately anchored to the nano-structured filaments, was observed. The filaments also induced in vitro osteogenic expression, as shown by the expression of osteocalcin and bone sialoprotein after 21 days of culture. This work deals with the fabrication of a new generation of nano-structured micro-filament for use as scaffolds of different shapes suited for bone cell engineering.

In Situ Detection of Water Leakage for Textile-Reinforced Composites.

By incorporating electrically conductive yarns into a waterproof membrane, one can detect epoxy resin cracking or liquid leakage. Therefore, this study examined the electrical conductivity variations of several yarns (metallic or carbon-based) for cracking and water detection. The first observations concerned the detectors' feasibility by investigating their conductivity variations during both their resin implementation processes and their resin cracking. Throughout this experiment, two phenomena were detected: the compression and the separation of the fibres by the resin. In addition, the resin cracking had an important role in decreasing the yarns' conductivity. The second part of this study concerned water detection. Two principles were established and implemented, first with yarns and then with yarns incorporated into the resin. First, the principle of absorption was based on the conductivity variation with the yarns' swelling after contact with water. A short circuit was established by the creation of a conductive path when a drop of water was deposited between two conductive, parallel yarns. Through the influence of the yarns' properties, this study explored the metallic yarns' capacity to better detect water with a short circuit and the ability of the carbon-based yarns to detect water by the principle of absorption.

The influence of 1-butanol and trisodium citrate ion on morphology and chemical properties of chitosan-based microcapsules during rigidification by alkali treatment.

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.

Green synthesis of MOF-based textile composites for the degradation of a chemical warfare agent simulant.

A green synthesis of UiO-66-NH2 embedded in chitosan and deposited on textiles has been investigated for the degradation of chemical warfare agents. This method requires no heating or use of toxic solvents. The composite synthesized presents an interesting efficiency in detoxifying common simulants of chemical warfare agents, such as DMNP. In parallel, resistance and permeability tests were also realized in order to confirm the suitability of the composites for further applications.

Assessing Alternative Pre-Treatment Methods to Promote Essential Oil Fixation into Cotton and Polyethylene Terephthalate Fiber: A Comparative Study.

This study aims to develop a new refreshing feeling, ecological, and antimicrobial fabrics for medicinal applications. The geranium essential oils (GEO) are incorporated into polyester and cotton fabrics by different methods, such as ultrasound, diffusion, and padding. The effect of solvent, nature of fibers, and treatment processes were evaluated via the thermal properties, the color strength, the odor intensity, the wash fastness, and the antibacterial activities of the fabrics. It was found that the ultrasound method was the most efficient process for incorporation of GEO. Ultrasound produced a great effect on the color strength of the treated fabrics, suggesting the absorption of geranium oil in fiber surface. The color strength (K/S) increased from 0.22 for the original fabric to 0.91 for the modified counterpart. In addition, the treated fibers showed appreciable antibacterial capacity against Gram-positive (Staphylococcus epidermidis) and Gram-negative (Escherichia coli) bacteria strains. Moreover, the ultrasound process can effectively guarantee the stability of geranium oil in fabrics without decreasing the significant odor intensity and antibacterial character. Based on the interesting properties like ecofriendliness, reusability, antibacterial, and a refreshing feeling, it was suggested that textile impregnated with geranium essential oil might be used as a potential material in cosmetic applications.

Piezoresistive Properties of 3D-Printed Polylactic Acid (PLA) Nanocomposites.

An increasing interest is focused on the application of 3D printing for sensor manufacturing. Using 3D printing technology offers a new approach to the fabrication of sensors that are both geometrically and functionally complex. This work presents the analysis of the 3D-printed thermoplastic nanocomposites compress under the applied force. The response for the corresponding resistance changes versus applied load is obtained to evaluate the effectiveness of the printed layer as a pressure/force sensor. Multi-walled carbon nanotubes (MWNT) and high-structured carbon black (Ketjenblack) (KB) in the polylactic acid (PLA) matrix were extruded to develop 3D-printable filaments. The electrical and piezoresistive behaviors of the created 3D-printed layers were investigated. The percolation threshold of MWNT and KB 3D-printed layers are 1 wt.% and 4 wt.%, respectively. The PLA/1 wt.% MWNT 3D-printed layers with 1 mm thickness exhibit a negative pressure coefficient (NPC) characterized by a decrease of about one decade in resistance with increasing compressive loadings up to 18 N with a maximum strain up to about 16%. In the cyclic mode with a 1 N/min force rate, the PLA/1 wt.% MWNT 3D-printed layers showed good performance with the piezoresistive coefficient or gauge factor (G) of 7.6 obtained with the amplitude of the piezoresistive response (Ar) of about -0.8. KB composites could not show stable piezoresistive responses in a cyclic mode. However, under high force rate compression, the PLA/4 wt.% KB 3D-printed layers led to responses of large sensitivity (Ar = -0.90) and were exempt from noise with a high value of G = 47.6 in the first cycle, which is a highly efficient piezoresistive behavior.

Microwave-Assisted Synthesis of Porous Composites MOF-Textile for the Protection against Chemical and Nuclear Hazards.

Since the emergence of chemical, biological, radiological, and nuclear risks, significant efforts have been made to create efficient personal protection equipment. Recently, metal-organic framework (MOF) materials have emerged as new promising candidates for the capture and degradation of various threats, like chemical warfare agents (CWAs) or radioactive species. Herein, we report a new synthesis method of MOF-textile composites by microwave irradiation, with direct anchoring of MOFs on textiles. The resistance of the composite has been tested using normed abrasion measurements, and non-stable samples were optimized. The protection capacity of the MOF-textile composite has been tested against dimethyl 4-nitrophenyl phosphate, a common CWA simulant, showing short degradation half-life (30 min). Radiological/nuclear protection has also been tested through uranium uptake (up to 15 mg g-1 adsorbent) and the capture of Kr or Xe gas at 0.9 and 2.9 cm3/g, respectively.

High-performance polylactide/ZnO nanocomposites designed for films and fibers with special end-use properties.

Metallic oxides have been successfully investigated for the recycling of polylactide (PLA) via catalyzed unzipping depolymerization allowing for the selective recovery of lactide monomer. In this contribution, a metallic oxide nanofiller, that is, ZnO, has been dispersed into PLA without detrimental polyester degradation yielding PLA/ZnO nanocomposites directly suitable for producing films and fibers. The nanocomposites were produced by melt-blending two different grades of PLA with untreated ZnO and surface-treated ZnO nanoparticles. The surface treatment by silanization proved to be necessary for avoiding the decrease in molecular weight and thermal and mechanical properties of the filled polyester matrix. Silane-treated ZnO nanoparticles yielded nanocomposites characterized by good mechanical performances (tensile strength in the interval from 55 to 65 MPa), improved thermal stability, and fine nanofiller dispersion, as evidenced by microscopy investigations. PLA/ZnO nanocomposites were further extruded in films and fibers, respectively, characterized by anti-UV and antibacterial properties.

Melt Spinning of Flexible and Conductive Immiscible Thermoplastic/Elastomer Monofilament for Water Detection.

In many textile fields, such as industrial structures or clothes, one way to detect a specific liquid leak is the electrical conductivity variation of a yarn. This yarn can be developed using melt spun of Conductive Polymer Composites (CPCs), which blend insulating polymer and electrically conductive fillers. This study examines the influence of the proportions of an immiscible thermoplastic/elastomer blend for its implementation and its water detection. The thermoplastic polymer used for the detection property is the polyamide 6.6 (PA6.6) filled with enough carbon nanotubes (CNT) to exceed the percolation threshold. However, the addition of fillers decreases the polymer fluidity, resulting in the difficulty to implement the CPC. Using an immiscible polymers blend with an elastomer, which is a propylene-based elastomer (PBE) permits to increase this fluidity and to create a flexible conductive monofilament. After characterizations (morphology, rheological and mechanical) of this blend (PA6.6CNT/PBE) in different proportions, two principles of water detection are established and carried out with the monofilaments: the principle of absorption and the short circuit. It is found that the morphology of the immiscible polymer blend had a significant role in the water detection.

Antibacterial Textile Based on Hydrolyzed Milk Casein.

Antimicrobial textile structures are developed based on polypropylene (PP) and a natural material, hydrolyzed casein. The casein, from bovine milk, is subjected to acid hydrolysis in aqueous media, then blended into the PP matrix in the melt phase by extrusion. The obtained blend, containing 5 wt.% of hydrolyzed casein, is then processed by a melt spinning process to get multifilaments, leading to the production knitting structures. Thanks to the addition of the hydrolyzed casein, the obtained textile showed a strong antibacterial activity towards both Gram (+) and Gram (-) bacterial strains. The addition of 5 wt.% hydrolyzed casein does not significantly impact the mechanical properties of PP in the dumbbells form, but a small decrease was observed in the tenacity of the filaments. No moisture retention was observed after the addition of hydrolyzed casein, but the rheological behavior was slightly affected. The obtained results can contribute to addressing concerns regarding nonrenewable antibacterial agents used in textile materials, particularly their effects on the environment and human health, by offering antibacterial agents from a biobased and edible substance with high efficiency. They are also promising to respond to issues of wasting dairy products and recycling them, in addition to the advantages of using melt processes.

Study of the Influence of PCL on the In Vitro Degradation of Extruded PLA Monofilaments and Melt-Spun Filaments.

This work presents the effect of a melt-spinning process on the degradation behavior of bioresorbable and immiscible poly(d,l-lactide) (PLA) and polycaprolactone (PCL) polymer blends. A large range of these blends, from PLA90PCL10 (90 wt% PLA and 10 wt% PCL) to PLA60PCL40 in increments of 10%, was processed via extrusion (diameter monofilament: ∅ ≈ 1 mm) and melt spinning (80 filaments: 50 to 70 µm each) to evaluate the impact of the PCL ratio and then melt spinning on the hydrolytic degradation of PLA, which allowed for highlighting the potential of a textile-based scaffold in bioresorbable implants. The morphologies of the structures were investigated via extracting PCL with acetic acid and scanning electron microscopy observations. Then, they were immersed in a Dulbecco's Modified Eagle Medium (DMEM) media at 50 °C for 35 days and their properties were tested in order to evaluate the relation between the morphology and the evolution of the crystallinity degree and the mechanical and physical properties. As expected, the incorporation of PCL into the PLA matrix slowed down the hydrolytic degradation. It was shown that the degradation became heterogeneous with a small ratio of PCL. Finally, melt spinning had an impact on the morphology, and consequently, on the other properties over time.

Influence of a Coaxial Electrospraying System on the n-Hexadecane/Polycaprolactone Phase Change Microcapsules Properties.

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 10-20 µm 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-1. In addition, it was also observed that the thermal stability was improved by using a coaxial system rather than a single nozzle.

Development of Flexible and Conductive Immiscible Thermoplastic/Elastomer Monofilament for Smart Textiles Applications Using 3D Printing.

3D printing utilized as a direct deposition of conductive polymeric materials onto textiles reveals to be an attractive technique in the development of functional textiles. However, the conductive fillers-filled thermoplastic polymers commonly used in the development of functional textiles through 3D printing technology and most specifically through Fused Deposition Modeling (FDM) process-are not appropriate for textile applications as they are excessively brittle and fragile at room temperature. Indeed, a large amount of fillers is incorporated into the polymers to attain the percolation threshold increasing their viscosity and stiffness. For this reason, this study focuses on enhancing the flexibility, stress and strain at rupture and electrical conductivity of 3D-printed conductive polymer onto textiles by developing various immiscible polymer blends. A phase is composed of a conductive polymer composite (CPC) made of a carbon nanotubes (CNT) and highly structured carbon black (KB)- filled low-density polyethylene (LDPE) and another one of propylene-based elastomer (PBE) blends. Two requirements are essential to create flexible and highly conductive monofilaments for 3D-printed polymers onto textile materials applications. First, the co-continuity of both the thermoplastic and the elastomer phases and the location of the conductive fillers in the thermoplastic phase or at the interface of the two immiscible polymers are necessary to preserve the flexibility of the elastomer while decreasing the global amount of charges in the blends. In the present work based on theoretical models, when using a two-step melt process, the KB and CNT particles are found to be both preferentially located at the LDPE/PBE interface. Moreover, in the case of the two-step extrusion, SEM characterization showed that the KB particles were located in the LDPE while the CNT were mainly at the LDPE/PBE interface and TEM analysis demonstrated that KB and CNT nanoparticles were in LDPE and at the interface. For one-step extrusion, it was found that both KB and CNT are in the PBE and LDPE phases. These selective locations play a key role in extending the co-continuity of the LDPE and PBE phases over a much larger composition range. Therefore, the melt flow index and the electrical conductivity of monofilament, the deformation under compression, the strain and stress and the electrical conductivity of the 3D-printed conducting polymer composite onto textiles were significantly improved with KB and CNT-filled LDPE/PBE blends compared to KB and CNT-filled LDPE separately. The two-step extrusion processed 60%(LDPE16.7% KB + 4.2% CNT)/40 PBE blends presented the best properties and almost similar to the ones of the textile materials and henceforth, could be a better material for functional textile development through 3D printing onto textiles.

Study of the Wear Resistance of Conductive Poly Lactic Acid Monofilament 3D Printed onto Polyethylene Terephthalate Woven Materials.

Wear resistance of conductive Poly Lactic Acid monofilament 3D printed onto textiles, through Fused Deposition Modeling (FDM) process and their electrical conductivity after abrasion are important to consider in the development of smart textiles with preserved mechanical and electrical properties. The study aims at investigating the weight loss after abrasion and end point of such materials, understanding the influence of the textile properties and 3D printing process parameters and studying the impact of the abrasion process on the electrical conductivity property of the 3D printed conductive polymers onto textiles. The effects of the 3D printing process and the printing parameters on the structural properties of textiles, such as the thickness of the conductive Poly Lactic Acid (PLA) 3D printed onto polyethylene terephthalate (PET) textile and the average pore sizes of its surface are also investigated. Findings demonstrate that the textile properties, such as the pattern and the process settings, for instance, the printing bed temperature, impact significantly the abrasion resistance of 3D printed conductive Poly Lactic Acid (PLA) onto PET woven textiles. Due to the higher capacity of the surface structure and stronger fiber-to-fiber cohesion, the 3D printed conductive polymer deposited onto textiles through Fused Deposition Modeling process have a higher abrasion resistance and lower weight loss after abrasion compared to the original fabrics. After printing the mean pore size, localized at the surface of the 3D-printed PLA onto PET textiles, is five to eight times smaller than the one of the pores localized at the surface of the PET fabrics prior to 3D printing. Finally, the abrasion process did considerably impact the electrical conductivity of 3D printed conductive PLA onto PET fabric.

Selection of Immiscible Polymer Blends Filled with Carbon Nanotubes for Heating Applications.

In many application fields, such as medicine or sports, heating textiles use electrically conductive multifilaments. This multifilament can be developed from conductive polymer composites (CPC), which are blends of an insulating polymer filled with electrically conductive particles. However, this multifilament must have filler content above the percolation threshold, which leads to an increase of the viscosity and problems during the melt spinning process. Immiscible blends between two polymers (one being a CPC) can be used to allow the reduction of the global filler content if each polymer is co-continuous with a selective localization of the fillers in only one polymer. In this study, three immiscible blends were developed between polypropylene, polyethylene terephthalate, or polyamide 6 and a filled polycaprolactone with carbon nanotubes. The morphology of each blend at different ratios was studied using models of co-continuity and prediction of fillers localization according to viscosity, interfacial energy, elastic modulus, and loss factor of each polymer. This theoretical approach was compared to experimental values to find out differences between methods. The electrical properties (electrical conductivity and Joule effect) were also studied. The co-continuity, the selective localization in the polycaprolactone, and the Joule effect were only exhibited by the polypropylene/filled polycaprolactone 50/50 wt.%.

Stress, strain and deformation of poly-lactic acid filament deposited onto polyethylene terephthalate woven fabric through 3D printing process.

Although direct deposition of polymeric materials onto textiles through 3D printing is a great technique used more and more to develop smart textiles, one of the main challenges is to demonstrate equal or better mechanical resistance, durability and comfort than those of the textile substrates before deposition process. This article focuses on studying the impact of the textile properties and printing platform temperature on the tensile and deformations of non-conductive and conductive poly lactic acid (PLA) filaments deposited onto polyethylene terephthalate (PET) textiles through 3D printing process and optimizing them using theoretical and statistical models. The results demonstrate that the deposition process affects the tensile properties of the printed textile in comparison with the ones of the textiles. The stress and strain at rupture of the first 3D printed PLA layer deposited onto PET textile material reveal to be a combination of those of the printed layer and the PET fabric due to the lower flexibility and diffusion of the polymeric printed track through the textile fabric leading to a weak adhesion at the polymer/textile interface. Besides, printing platform temperature and textile properties influence the tensile and deformation properties of the 3D printed PLA on PET textile significantly. Both, the washing process and the incorporation of conductive fillers into the PLA do not affect the tensile properties of the extruded polymeric materials. The elastic, total and permanent deformations of the 3D-printed PLA on PET fabrics are lower than the ones of the fabric before polymer deposition which demonstrates a better dimensional stability, higher stiffness and lower flexibility of these materials.

[When textiles help your recovery]. / Quand les textiles vous soignent.

Textiles are widely used in the biomedical domain, particularly in wound dressings or as implantable devices for strengthening or even replacing some damaged organs. Nowadays they present more and more sophisticated functionalities contributing to the healing process, to the organs regeneration, and fight against infection or thrombosis. Advanced spinning technologies of biostable or bioresorbable polymers and surface treatment technologies are often used, as well as nanotechnologies, to implement two main strategies for development of bio-active textiles. A long or medium term technology is obtained by grafting the bio-active molecule through stable chemical bonds while a short term activity is produced by using "reservoir" systems such as hydrogels and cyclodextrins that release the active agents in situ. ‡.

Development of multilayer microcapsules by a phase coacervation method based on ionic interactions for textile applications.

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.

Development of superhydrophilic and superhydrophobic polyester fabric by growing zinc oxide nanorods.

ZnO nanorods were grown on microfibers of Polyethylene terephthalate (PET) fabric by seeding method to develop hierarchical roughness structure. XRD and XPS analysis show the presence of crystalline ZnO and chemical Zn species at the fiber surface at each stage of the process. Five series of samples with different seed concentrations have been realized, and their surface morphology and topography were characterized by AFM and SEM. Increasing seed concentrations lead to samples with superhydrophilic properties. Not only the water contact angle at fabric surface tends to zero but also the water capillary diffusion inside fabric is faster. Nanostructuration affects the structure inside the fabric, and further experiments with decane liquid have been made to get a better understanding of this effect. To study the superhydrophobicity, nanorods treated samples were modified with octadecyltrimethoxysilane (ODS) by two method; solution deposition and vapor deposition. The superhydrophobicity was characterized by measuring the water contact angle and water sliding angle with 5 µl water droplet. The samples modified with ODS by vapor deposition showed higher water contact angles and low water sliding angle than the ones modified with solution method. The lotus effect has been well correlated with the surface morphology of the nanorods structured fibers. The application of the Cassie-Baxter equation is discussed.

Preparation of microcapsules with multi-layers structure stabilized by chitosan and sodium dodecyl sulfate.

The microcapsules with oil core and multi-layers shell were developed from poly-cationic chitosan (CS) and anionic SDS in multistep electrostatic layer by layer deposition technique combined with oil in water emulsification process. The net charge of microcapsules determined by zeta potential indicated that microcapsules are highly positive charged because of poly-cationic nature of CS, and charge neutralization of microcapsules occurred after alkali treatment. The granulometry measurement showed increase in average diameter of microcapsules by alkali treatment suggesting swelling or formation of small aggregates. The morphology analysis of microcapsules by optical microscopy corroborated the results of granulometry, and diameter of microcapsules was found to be decreased in multistep process due to tight packing of layers in outer shell of microcapsules. The alkali treatment of microcapsules to solidify outer shell was optimized with 0.02 N NaOH to reduce microcapsules aggregation and gel formation by CS chains as found in optical micrographs.