BACKGROUND:Soft-tissue reconstruction is crucial in fields such as plastic surgery and oncology to address the repair of damaged tissues. Knitted scaffolds from bioresorbable copolymers, specifically poly(D,L-lactide) (PLA) and polycaprolactone (PCL), offer mechanical and biological properties that are essential for tissue engineering. This study assessed three-dimensional knitted scaffolds fabricated from melt-spun PLA and PCL multifilaments for soft tissue engineering applications. It examined the impact of the PLA/PCL ratio on the knitted scaffold structure, mechanical properties, and biological responses to determine the optimal composition for adipose tissue reconstruction. RESULTS:Knitted scaffolds fabricated with the PLA/PCL blends (PLA70/PCL30 and PLA90/PCL10) exhibited distinct mechanical and biological profiles. PLA70/PCL30 scaffolds with a higher PCL content showed enhanced elasticity and porosity, whereas PLA90/PCL10 scaffolds maintained better structural integrity and stiffness. Biological assays confirmed the biocompatibility of all scaffolds in vitro, with no cytotoxic effects. The scaffolds supported adipogenic differentiation in vitro, although PLA70/PCL30 exhibited slightly reduced efficacy. Vascularization was evident using chorioallantoic membrane assays, in which blood vessel formation and penetration were observed, regardless of the scaffold composition. In vivo implantation in rat models revealed effective adipocyte integration, structural stability, and minimal inflammatory response, with PLA90/PCL10 scaffolds outperforming PLA70/PCL30 in terms of vascularization and less macrophage infiltration of connective tissue. CONCLUSION:PLA/PCL knitted scaffolds offer a promising solution for enhancing graft volume maintenance and improving long-term outcomes, with tunable mechanical properties and biodegradability. The PLA90/PCL10 scaffold is a superior candidate for adipose tissue reconstruction, balancing the structural stability with biological compatibility. These findings underscore the potential of PLA/PCL scaffolds for reconstructive surgery. Future studies should focus on scalability and long-term biocompatibility to facilitate clinical translation.

Many textile fields, such as industrial structures or clothing, use the electrical conductivity variation of yarns to detect fluid leakage. Such yarns can be developed by melt spinning conductive polymer composites (CPC). CPC filaments are composed of a polymer’s matrix which is blended with sufficient quantity of electrically conductive fillers to make the filament conductive. To combine properties or improve the compounds preparation, more and more studies are investigating different polymers blends. In this study, CPC monofilaments and multifilaments are developed and characterized to observe the formulation influence on spinnability and the implementation process on the water detection. Two principles of water detection are studied on the CPC which is composed of a blend of partially miscible polymers (polyethylene terephthalate (PET)/polybutylene terephthalate (PBT)) filled with carbon nanotubes (CNT). The principle of absorption is based on the electrical conductivity variation of the filament in contact with water. For the short circuit principle, the presence of the liquid is detected when the water creates a conductive path between two filaments in parallel.

Correction for 'Environmentally responsive hydrogel composites for dynamic body thermoregulation' by M. Garzón Altamirano et al., Soft Matter, 2023, 19, 2360-2369, https://doi.org/10.1039/D2SM01548J.

Efficient thermal management is essential for the energy balance and thermal comfort. In this context, the design of textiles, which can modulate the infrared radiation emitted by the human body, is attractive. These fabrics will manage the microclimate between the skin and fabric. The proposed textile design consists of the coating of commercial woven fabrics based on polyamide 6-6 by a dip-coating process. The coating is based on the incorporation of fine spherical silica particles with a submicron size within thermosensitive poly(N-isopropylacrylamide) hydrogels. Neat commercial fabrics reflect 12% of the radiation, while the addition of silica particles leads to a reflection of 24% of the infrared radiation in the 5-15 mu m wavelengths range. The infrared radiation reflection capacity of the coated fabrics can be increased by managing the size and the content of the silica particles, which allows reaching 36% of reflected radiation. Our findings open opportunities for warming up fabrics and thus reduce energy consumption in heating close space.

Hydrogel composites exhibiting dynamic thermo-hydro responsive modulation of infrared radiation (IR) in the 5-15 μm range are designed for personalized body thermoregulation. Fabrication of the proposed system relies on the periodic arrangement of submicron-sized spherical fine silica (SiO2) particles within poly(N-isopropylacrylamide) (PNIPAM)-based hydrogels. The dependence of the SiO2 particles content on the IR reflection, followed by its modulation in response to any immediate environmental changes are thereby investigated. The addition of 20 wt% of SiO2 allowed the hydrogel composites to reflect 20% of the IR emitted by the human body at constant temperature (i.e. T = 20 °C) and relative humidity (i.e. RH = 0%). According to Bragg's law, we found that the smaller the distance between the SiO2 particles, the higher the IR reflection. The IR reflection further increased to a maximum of 42% when the resulting hydrogel composites are subjected to changes in relative humidity (i.e. RH = 60%) and temperature (i.e. T = 35 °C). Thermography is used to map the IR radiation emitted from the hydrogel composites when placed on the skin of the human body, demonstrating that the composite is actually reflecting IR. The latter results are supported by theoretical models that define the IR reflection profile of the resulting hydrogel composites with respect to the silica content, relative humidity and temperature.

In order to avoid environmental pollution by effluents, the incorporation of electrical conductive yarns in a waterproof membrane allows detecting a leak or crack on industrial concrete structure. The membrane is made of composite materials: a glass textile structure equipped with the detector yarns and molded in an epoxy resin. The liquid’s detection and the data’s transmission depend on the yarn’s conductivity variation and its chemical and physical properties. This study aims to develop a water detector monofilament from conductive polymer composites (CPC): an immiscible polymers blend (polyamide 6.6/elastomer) filled with carbon nanotubes (CNT). The addition of elastomer in the CPC yarn is important to withstand the mechanical deformation of the resin structure without breaking. The morphology of the immiscible polymers blend and the localization of the CNT influence the electrical conductivity of the yarn and thus, its property of water detection. Two principles of water detection are investigated with this blend: the short circuit and the absorption. For the short circuit, the presence of liquid is detected when the liquid creates a conductive path between two yarns in parallel. While, the absorption principle is based on the conductivity variation with the yarn’s swelling in contact with water.

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.

Nowadays, the heating textiles are used in many fields of applications as medicine or comfort. The heating property for the most part of these textiles was ensured by electrical conductive fiber as metallic yarn thanks to Joule Effect. A challenge for heating textile is to have an electrical conductive fiber which has a temperature self-regulation at the comfort temperature. Thanks to this temperature self-regulation, the heating textile reaches more autonomy. To develop this kind of textile, conductive polymer composite (CPC), which is the combination between an insulating polymer and electrical conductivity nanofillers [1], is made by melt spinning. The temperature self-regulation is provided by the positive temperature coefficient (PTC) effect, which allows switching between an electrical conductivity state and an insulating state when the CPC is close to a transition phase temperature (glass transition temperature or melt temperature). However, when the PTC effect can take place at the melting point, the mechanical properties are not involved. So to maintain the final product an immiscible polymer blend was used: one polymer was the CPC and the second polymer was an insulating polymer with a higher melting point than the target temperature. In fact, the CPC involve the electrical conductivity and the PTC effect, whereas the insulating polymer involves the mechanical properties. However, a high electrical conductivity is necessary to reach the comfort temperature (defined around 42°) by Joule Effect. So to reach this temperature, the coating on a metallic yarn by the conductive immiscible polymer blend was used. The electrical conductivity of this product was improved by the metallic yarn and the self-regulating temperature by the PTC effect of the immiscible polymer blend (figure 1). In this paper the immiscible polymer blend used is a polycaprolactone (PCL) filled with multiwall carbon nanotubes (MWCNT) and a polypropylene (PP). In fact, in a previous paper the co-continuity and the selective localisation of the fillers in the PCL for this blend was studied [2]. The influence of the thickness CPC coating and the influence of the structure of metallic yarn were studied on the electrical conductivity, the Joule Effect and PTC effect.

The human body exchanges heat through the environment by various means, such as radiation, evaporation, conduction, and convection. Thermo-physiological comfort is associated with the effective heat transfer between the body and the atmosphere, maintaining the body temperature in a tolerable thermal range (36.5–37.5ºC). In order to ensure comfort, the body heat must be preserved or emitted, depending on external conditions. If the body heat is not properly managed, it can cause hyperthermia, heatstroke, and thermal discomfort. Conventionally, heating, ventilation, and air conditioning systems are used to provide comfort. However, they require a huge amount of energy, leading to an increase in global warming, and are limited to indoor applications. In recent decades, scientists across the world have been working to provide thermal comfort through wearable innovative textiles. This review article presents recent innovative strategies for moisture and/or thermal management at the material, filament/fiber, yarn, and fabric scales. It also summarizes the passive/active textile models for comfort. Integrating electrical devices in garments can rapidly control the skin temperature, and is dynamic and useful for a wide range of environmental conditions. However, their use can be limited in some situations due to their bulky design and batteries, which must be frequently recharged. Furthermore, adaptive textiles enable the wearer to maintain comfort in various temperatures and humidity without requiring batteries. Using these wearable textiles is convenient to provide thermal comfort at the individual level rather than controlling the entire building temperature.

The immiscible polymeric blend of polypropylene (PP) and polyvinyl alcohol (PVA) was manufactured into multifilament fibers via the melt-spinning process, of which the mass ratio of PP to PVA was selected as 30%/70%.The PP micro/nanofibers were accessible with the removal of PVA in hot water.Kaolinite particles were also incorporated to modify the micro/nanofibers surface, for functionalization efficiencies play a useful role with the aid of a high specific surface area.The octahedral layers of kaolinite particles were grafted with a regioselective process by octadecyl (C 18 H 37 -) groups modified into Janus particles to better localize the fillers at the biphasic interface.As a result, the kaolinite particles having a Janus morphology are more distributed at the interface of the polymers, as observed by SEM.The knitting structures are capable of being maintained after the selective phase extraction leaving numbers of micro/nanofibers.After the incorporation of kaolinite particles, there are still some amounts of particles appearing on the surface of PP micro/nanofibers.Besides, there is a mechanical enhancement of the knitted fabrics, especially when the Janus particles are used, even after the selective phase extraction, which the conventional chemical treatment cannot bring.This study sets an example of fabricating PP micro/nanofiber fabrics surface-modified and mechanically enhanced using Janus kaolinite particles.

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.

Poly(vinylidene fluoride) (PVDF) fibres used to develop sensors or energy harvesters have great potential in the sector of portable electronic devices and especially in the development of smart textiles. This polymorphic polymer is known for several years for its excellent piezoelectric properties related to its different crystalline phases and more particularly to the polar beta-phase is the subject of studies dedicated to the development, optimization, and characterization of beta-PVDF fibres. The presence and the evolution of the different crystalline phases are linked to different factors and can be controlled for example by changing some parameters during the process. In the case of the spinning process, the influence of the operating conditions, such as temperature and drawing on the crystalline structure is currently determined by post-mortem analyses. Development of 'mimetic' tests to characterize in situ the evolution of the crystalline structure of a mechanically stretched polymer is a possible way. Nevertheless, this cannot totally reproduce a real process. For the first time, phase transformations and evolutions of PVDF during a melt-spinning process were studied online thanks to in situ Raman spectroscopy measurements. Performed at different stages of the spinning line, this method allows us to follow the evolution of the crystalline phases in real time, during the key steps of the process and to conclude on the conditions for obtaining the piezoelectric phase. The successful online characterization of PVDF crystalline phases by Raman spectroscopy opens new perspectives for the optimization of these fibres by controlling the evolution of the structure when changing process parameters.

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 PP 70 –PVA 30 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.

Abstract With a final view to prototyping a textile energy harvesting system, piezoelectric textile structures based on 100% poly(vinylidene fluoride) (PVDF) were developed and characterized. Multifilaments of 246 tex were produced by melt spinning. The mechanical stretching during the process provides PVDF fibers with an optimal β-phase ratio (97%). Some studies have already been carried out on piezoelectric PVDF-based structures as films or textiles. The goal of the study is the investigation of the differences between 2D and 3D woven fabrics structures from piezoelectric PVDF multifilament yarns. The textile structures were poled after the weaving process, and a maximum output voltage of 2.3 V was observed on an angle - through-the-thickness interlock (interlock 3D structure) under compression by DMA tests. Energy harvesting is optimized in a 3D interlock thanks to the stresses of the multifilaments in the thickness. This finding has led to the design of an inner sole prototype from a knitting structure and another structure with piezoelectric fibers outside the plane of the fabric. The prototype is able to harvest energy and the results are consistent with the measurement realized with DMA under dynamic compression close to walking.

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.

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 by octadecylphosphonic acid allowed the localization of the particles at the PP-PVA interface. Then surface-modified PP porous fibers have been obtained by selective extraction of the PVA phase. The SEM observations and selective extraction experiments indicated that the unmodified kaolinite particles were localized within the PVA phase having limited impact on the PVA accessibility, while Janus-modified particles were distributed at the biphasic interface decreasing significantly the PVA accessibility. The volume average diameter of PVA within annealed blends is dramatically decreased from 73.3 to 13.6 mu m by the addition of 5 wt % of Janus kaolinite particles, proving the strong compatibility effect. Gel-like behavior was also observed in rheological investigations for blends filled with modified kaolinite. The melt flow index (MFI) was tested for adapting the conditions of melt spinning. The PVA accessibility can reach more than 90%, and the interface-located fillers can enhance the Young's modulus of the biphasic fibers with 57% increment. The crystallization structure of the porous PP fibers was also influenced by the Janus kaolinite particles, with the enhancement of crystal perfection.

Energy harvesting is a promising concept that can be used in the development of smart textiles to solve one of the major issues: energy supply. Producing PVDF piezoelectric fibers is a possible way. However, to ensure the piezoelectric character and lead an electromechanical conversion its β phase is needed. The modification of crystalline phases is linked to the processing parameters. In-situ Raman spectroscopy measurements are made on a spinning device used for new synthetic fibers developments or small productions. The content of the crystalline phases α and β is measured for the first time at key points of such process.