Elastomeric Poly Research Articles

Ultrasoft and High-Mobility Block Copolymers for Skin-Compatible Electronics.

Polymer semiconductors (PSCs) are an essential component of organic field-effect transistors (OFETs), but their potential for stretchable electronics is limited by their brittleness and failure susceptibility upon strain. Herein, a covalent connection of two state-of-the-art polymers-semiconducting poly-diketo-pyrrolopyrrole-thienothiophene (PDPP-TT) and elastomeric poly(dimethylsiloxane) (PDMS)-in a single triblock copolymer (TBC) chain is reported, which enables high charge carrier mobility and low modulus in one system. Three TBCs containing up to 65 wt% PDMS were obtained, and the TBC with 65 wt% PDMS content exhibits mobilities up to 0.1 cm2 V-1 s-1 , in the range of the fully conjugated reference polymer PDPP-TT (0.7 cm2 V-1 s-1 ). The TBC is ultrasoft with a low elastic modulus (5 MPa) in the range of mammalian tissue. The TBC exhibits an excellent stretchability and extraordinary durability, fully maintaining the initial electric conductivity in a doped state after 1500 cycles to 50% strain.

Combination of in vitro thermally-accelerated ageing and Fourier-Transform Infrared spectroscopy to predict scaffold lifetime

Biodegradable elastomers face a growing use in soft tissue engineering due to the possibility to tune, by an appropriate selection of the synthesis and process conditions, the material thermo-mechanical properties to match the stress–strain behavior of the tissue to replace. However, changes in material properties can impact drastically the scaffold durability and therefore the efficiency of tissue reconstruction. Few studies focus on approaches allowing the prediction of the scaffold lifetime, while there is a need for strategies using accelerated testing protocols and versatile tools to easily investigate on the material degradation rate.In the present study, elastomeric cross-linked poly(ester-urethane-urea) scaffolds have been developed through an emulsion technique allowing to produce highly interconnected porous structure. Thermally-accelerated ageing was performed in cell culture medium at different temperatures: 37°C, 55°C, 75°C and 90°C. The degradation process was followed by gravimetry, swelling measurements, compression tests and infrared spectroscopy. The study revealed that the scaffold chemical composition variation was temperature dependant and its analysis by Fourier-Transform infrared spectroscopy allowed an easy determination of the activation energy of the hydrolytic degradation process, leading to the prediction of the scaffold lifetime at 37°C using Arrhenius extrapolation. This approach could be used to simply and straightforwardly screen the durability of new scaffolds.

Influence of Morphology on Fracture Propagation of PMMAe/PC Blend in Tensile Tests at High Strain Rate

AbstractThe aim of this study is to evaluate toughness mechanism of elastomeric poly(methyl methacrylate) (PMMAe) and polycarbonate (PC) blend through crack propagation at high speed tensile tests. Samples are processed using two types of extruders, single and twin screw, in order to eliminate the influence of processing in the final product's properties. Pure polymers and polymer blend samples are cryo‐ultramicrotomed and their morphology is characterized using atomic force microscopy (AFM). Fractured samples obtained from uniaxial tensile tests at high strain rate are inspected using optical microscopy (OM) and scanning electron microscopy (SEM). The results obtained for the PMMAe/PC blend in tests at high deformation rate showed that the shear rate during the mixing process influences the maximum strength of the polymer blend near its region of co‐continuous morphology. The visual evaluation of the fracture surface and the fractographic analysis corroborated the results of this study of polymer toughening.

Itaconate Based Elastomer as a Green Alternative to Styrene–Butadiene Rubber for Engineering Applications: Performance Comparison

In response to increasingly stringent requirements for the sustainability and environmental friendliness of the rubber industry, the application and development of bio-based elastomers have received extensive attention. In this work, we prepared a new type of bio-based elastomer poly(dibutyl itaconate-butadiene) copolymer (PDBIB) nanocomposite using carbon black and non-petroleum-based silica with a coupling agent. Using dynamic thermodynamic analysis (DMTA) and scanning electron microscope (SEM), we studied the effects of feed ratio on dynamic mechanical properties, micro morphology, and filler dispersion of PDBIB composites. Among them, silica-reinforced PDBIB60 (weight ratio of dibutyl itaconate to butadiene 40/60) and carbon black-reinforced PDBIB70 (weight ratio of dibutyl itaconate to butadiene 30/70) both showed excellent performance, such as tensile strength higher than 18 MPa and an elongation break higher than 400%. Compared with the widely used ESBR, the results showed that PDBIB had better rolling resistance and heat generation than ESBR. In addition, considering the development of green tires, we compared it with the solution polymerized styrene–butadiene rubber with better comprehensive performance, and analyzed the advantages of PDBIB and the areas to be improved. In summary, PDBIB prepared from bio-based monomers had superior performance and is of great significance for achieving sustainable development, providing a direction for the development of high-performance green tire and holding great potential to replace petroleum-derived elastomers.

Stretchable, self-healing, conductive hydrogel fibers for strain sensing and triboelectric energy-harvesting smart textiles

Abstract Stretchable conductive fibers are essential for smart electronic textiles (E-textiles). Here, we develop a continuous dry-wet spinning approach to fabricate stretchable, conductive and self-healing hydrogel fibers. By tuning the contents of acrylamide (AAm) and N-acryloylglycinamide (NAGA), the physically cross-linked poly (NAGA-co-AAm) (PNA) hydrogel precursor exhibits thermally reversible sol-gel transition, which ensures the success of the spinning process. The obtained PNA hydrogel fiber achieves excellent tensile strength (2.27 Mpa), stretchability (900%), high conductivity (0.69 S m−1), and self-healing capability. With an elastomeric poly (methyl acrylate) (PMA) coating, the PNA/PMA core-sheath fiber shows excellent resistance to water evaporation and absorption. The strain sensing capability of the PNA/PMA fiber is demonstrated for monitoring human body motions. Furthermore, a triboelectric nanogenerator (TENG) textile woven from the PNA/PMA fibers is fabricated to convert mechanical motion energy into electric power. Our stretchable conductive hydrogel fibers suggest great potentials for next-generation multifunctional smart textiles and wearable electronics.

Bent‐But‐Not‐Broken: Reactive Metal‐Organic Framework Composites from Elastomeric Phase‐Inverted Polymers

AbstractA phase inversion process is used to fabricate composite beads from the metal–organic framework (MOF) UiO‐66‐NH2 and the elastomeric block copolymer poly(styrene‐block‐ethylene‐ran‐butylene‐block‐styrene) (SEBS) for improved performance over activated carbon‐based protective textiles. Textiles incorporating the best MOF‐composite materials reduced steady‐state permeation of the chemical warfare agent (CWAs) simulant, 2‐chloroethyl ethyl sulfide (CEES), by ≈60% versus activated carbon cloth. Additionally, the protection capabilities of the composite beads could be further tuned by adjusting bead size—textiles fabricated from smaller composite beads show enhanced diffusional properties whereas textiles generated from larger beads maximize protective capacity. The elastomeric beads also do not exhibit any attrition when subjected to a hardness test, whereas traditional pressing techniques result in materials with only a 20% retention of particle size. Furthermore, composites with increasing MOF content result in enhanced chemical capacity and reactivity, with the best composite outperforming activated carbon cloth against the CWAs soman (91% versus 17% reacted, respectively) and mustard (97% versus 0% reacted, respectively) over 24 h. The 80 wt% samples also have ≈1.4 and 2.2× higher adsorption capacity for soman and CEES, respectively, versus carbon cloth. Finally, mixing multiple MOFs results in optimal composites for the simultaneous filtration of chlorine and ammonia.

The Effect of Poly(ethylene glycol) (PEG) Length on the Wettability and Surface Chemistry of PEG-Fluoroalkyl-Modified Polystyrene Diblock Copolymers and Their Two-Layer Films with Elastomer Matrix.

Diblock copolymers composed of a polystyrene first block and a PEG-fluoroalkyl chain-modified polystyrene second block were synthesized by controlled atom transfer radical polymerization (ATRP), starting from the same polystyrene macroinitiator. The wettability of the polymer film surfaces was investigated by measurements of static and dynamic contact angles. An increase in advancing water contact angle was evident for all the films after immersion in water for short times (10 and 1000 s), consistent with an unusual contraphilic switch of the PEG-fluoroalkyl side chains. Such a contraphilic response also accounted for the retained wettability of the polymer films upon prolonged contact with water, without an anticipated increase in the hydrophilic character. The copolymers were then used as surface-active modifiers of elastomer poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS)-based two-layer films. The elastomeric behavior of the films was varied by using SEBS matrices with different amounts of polystyrene. Whereas the mechanical properties strictly resembled those of the nature of the SEBS matrix, the surface properties were imposed by the additive. The contraphilic switch of the PEG-fluoroalkyl side chains resulted in an exceptionally high enrichment in fluorine of the film surface after immersion in water for seven days.

Facile fabrication of stretchable and compressible strain sensors by coating and integrating low-cost melamine foam scaffolds with reduced graphene oxide and poly (styrene-b-ethylene-butylene-b-styrene)

With the progress of intelligent electronic equipment, flexible and wearable strain sensors are being widely used in various applications such as electronic skins and smart robot. In this work, we proposed a facile method for the preparation of stretchable strain sensors as well as compressible strain sensors by using commercially available melamine form (MF). Firstly, MF was coated with reduced graphene oxide (rGO) to construct conductive networks via layer-by-layer assembly of polyethyleneimine and graphene oxide followed by chemical reduction. Thermoplastic elastomer poly (styrene-b-ethylene-butylene-b-styrene) (SEBS) was then infused into the MF@rGO scaffolds through solution absorption method. By adjusting the concentration of SEBS solution used, stretchable and compressible strain sensors were fabricated and both of them exhibited excellent mechanical properties, sensitive responsiveness and electromechanical durability. The deformation capacity of these two types of sensors could reach as high as 50% strain and the maximum gauge factors of stretchable and compressible strain sensors was 2.43 and 1.74, respectively. Stable signals during at least 1000 cycles for both stretchable and compressible strain sensors were well maintained. The potential sensing application of real-time monitoring of human motions was also demonstrated.

Fluoroelastomer encapsulation for enhanced reliability of solution-processed carbon nanotube thin-film transistors

Single-walled carbon nanotube (SWCNT) has attracted considerable attention as a promising semiconducting material due to its high field-effect mobility, high current-carrying capability, and superior mechanical durability. However, SWCNT-based thin-film transistors (SWCNT-TFTs) generally show insufficient electrical reliability in terms of the drain-current hysteresis and threshold voltage shift under the bias stress. To facilitate the great advantages of SWCNT in commercial electronic devices, strategies are required for enhancing the electrical reliability of SWCNT-TFTs without compromising their mechanical flexibility. In this work, we demonstrate solution-processed, hysteresis-free, and bias-stable SWCNT-TFTs encapsulated with elastomeric poly(vinylidene fluoride-co-hexafluoropropylene) (e-PVDF-HFP) using a lamination method. The dipolar nature of e-PVDF-HFP suppresses the charge trapping, resulting in elimination of hysteresis as well as enhancement of field-effect mobility and subthreshold slope. The bias instability under the negative gate bias stress is also alleviated because the hydrophobic encapsulation layer can exclude physisorbed water/oxygen molecules on the hydrophilic surface. Besides, our solvent-free lamination method effectively prevents the potential damages of the active and electrode layers from the use of the solvents. The proposed encapsulation method with laminating the e-PVDF-HFP film can provide a possibility for realization of wearable applications based on highly reliable solution-processed SWCNT-TFT.

Bioactive Anti-inflammatory, Antibacterial, Antioxidative Silicon-Based Nanofibrous Dressing Enables Cutaneous Tumor Photothermo-Chemo Therapy and Infection-Induced Wound Healing.

Traditional skin tumor surgery and chronic bacterial-infection-induced wound healing/skin regeneration is still a challenge. The ideal strategy should eliminate the tumor, enhance wound healing/skin formation, and be anti-infection. Herein, we designed a multifunctional elastomeric poly(l-lactic acid)-poly(citrate siloxane)-curcumin@polydopamine hybrid nanofibrous scaffold (denoted as PPCP matrix) for tumor-infection therapy and infection-induced wound healing. The PPCP matrix showed intrinsically multifunctional properties including antioxidative, anti-inflammatory, photothermal, antibacterial, anticancer, and angiogenesis bioactivities. The polydopamine/curcumin presented an excellent near-infrared photothermal/cancer cell toxicity capacity, respectively, which supported PPCP for synergetic skin tumor therapy and antibacterial properties in vitro/in vivo. Additionally, the PPCP nanofibrous matrix significantly promotes the adhesion and proliferation of normal skin cells and accelerates the cutaneous wound healing in normal mice and bacterial-infected mice by enhancing the early angiogenesis. The PPCP nanofibrous matrix with multifunctional bioactivities provides a competitive strategy for skin tumor and bacterial-infection-induced wound healing.

Formation of highly elastomeric and property-tailorable poly(glycerol sebacate)-co-poly(ethylene glycol) hydrogels through thiol-norbornene photochemistry.

Poly(glycerol sebacate) (PGS) is a synthetic biorubber that presents good biocompatibility, excellent elasticity and desirable mechanical properties for biomedical applications; however, the inherent hydrophobicity and traditional thermal curing of PGS restrict its use in the fabrication of hydrogels for advanced bioapplications. Here, we designed a new class of hydrophilic PGS-based copolymers that allow hydrogel formation through thiol-norbornene chemistry. Poly(glycerol sebacate)-co-polyethylene glycol (PGS-co-PEG) macromers were synthesized through a stepwise polycondensation reaction, and then the norbornene functional groups were introduced to the PGS-co-PEG structure to form norbornene-functionalized PGS-co-PEG (Nor_PGS-co-PEG). Nor_PGS-co-PEG macromers can be crosslinked using dithiols to prepare hydrogels in the presence of light and photoinitiators. The mechanical, swelling and degradation properties of Nor_PGS-co-PEG hydrogels can be controlled by altering the crosslinker amount. In particular, the elongation of Nor_PGS-co-PEG hydrogels can be modulated up to 950%. Nor_PGS-co-PEG can be processed using electrospinning and 3D printing techniques to generate microfibrous scaffolds and printed structures, respectively. In addition, the cytocompatibility of Nor_PGS-co-PEG was also demonstrated using in vitro cellular viability studies. These results indicate that Nor_PGS-co-PEG is a promising biomaterial with definable properties for scaffold manufacturing, presenting a great potential for biomedical applications.

Prevention of excessive scar formation using nanofibrous meshes made of biodegradable elastomer poly(3-hydroxybutyrate-co-3-hydroxyvalerate)

To reduce excessive scarring in wound healing, electrospun nanofibrous meshes, composed of haloarchaea-produced biodegradable elastomer poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), are fabricated for use as a wound dressing. Three PHBV polymers with different 3HV content are used to prepare either solution-cast films or electrospun nanofibrous meshes. As 3HV content increases, the crystallinity decreases and the scaffolds become more elastic. The nanofibrous meshes exhibit greater elasticity and elongation at break than films. When used to culture human dermal fibroblasts in vitro, PHBV meshes give better cell attachment and proliferation, less differentiation to myofibroblasts, and less substrate contraction. In a full-thickness mouse wound model, treatment with films or meshes enables regeneration of pale thin tissues without scabs, dehydration, or tubercular scar formation. The epidermis of wounds treated with meshes develop small invaginations in the dermis within 2 weeks, indicating hair follicle and sweat gland regeneration. Consistent with the in vitro results, meshes reduce myofibroblast differentiation in vivo through downregulation of α-SMA and TGF-β1, and upregulation of TGF-β3. The regenerated wounds treated with meshes are softer and more elastic than those treated with films. These results demonstrate that electrospun nanofibrous PHBV meshes mitigate excessive scar formation by regulating myofibroblast formation, showing their promise for use as wound dressings.

Architectured helically coiled scaffolds from elastomeric poly(butylene succinate) (PBS) copolyester via wet electrospinning

Electrospinning is one of the most investigated methods used to produce polymeric fiber scaffolds that mimic the morphology of native extracellular matrix. These structures have been extensively studied in the context of scaffolds for tissue regeneration. However, the compactness of materials obtained by traditional electrospinning, collected as two-dimensional non-woven scaffolds, can limit cell infiltration and tissue ingrowth. In addition, for applications in smooth muscle tissue engineering, highly elastic scaffolds capable of withstanding cyclic mechanical strains without suffering significant permanent deformations are preferred. In order to address these challenges, we report the fabrication of microscale 3D helically coiled scaffolds (referred as 3D-HCS) by wet-electrospinning method, a modification of the traditional electrospinning process in which a coagulation bath (non-solvent system for the electrospun material) is used as the collector. The present study, for the first time, successfully demonstrates the feasibility of using this method to produce various architectures of 3D helically coiled scaffolds (HCS) from segmented copolyester of poly (butylene succinate-co-dilinoleic succinate) (PBS-DLS), a thermoplastic elastomer. We examined the role of process parameters and propose a mechanism for the HCS formation. Fabricated 3D-HCS showed high specific surface area, high porosity, and good elasticity. Further, the marked increase in cell proliferation on 3D-HCS confirmed the suitability of these materials as scaffolds for soft tissue engineering.

Design, Preparation, and Evaluation of a Novel Elastomer with Bio-Based Diethyl Itaconate Aiming at High-Temperature Oil Resistance

A novel elastomer poly(diethyl itaconate-co-butyl acrylate-co-ethyl acrylate-co-glycidyl methacrylate) (PDEBEG) was designed and synthesized by redox emulsion polymerization based on bio-based diethyl itaconate, butyl acrylate, ethyl acrylate, and glycidyl methacrylate. The PDEBEG has a number average molecular weight of more than 200,000 and the yield is up to 96%. It is easy to control the glass transition temperature of the PDEBEG, which is ranged from −25.2 to −0.8 °C, by adjusting the monomer ratio. We prepared PDEBEG/CB composites by mixing PDEBEG with carbon black N330 and studied the oil resistance of the composites. The results show that the tensile strength and the elongation at break of the composites with 10 wt% diethyl itaconate can reach up to 14.5 MPa and 305%, respectively. The mechanical properties and high-temperature oil resistance of the composites are superior to that of the commercially available acrylate rubber AR72LS.

Biomimetic Elastomeric Bioactive Siloxane‐Based Hybrid Nanofibrous Scaffolds with miRNA Activation: A Joint Physico‐Chemical‐Biological Strategy for Promoting Bone Regeneration

AbstractRapid and efficient disease‐induced or critical‐size bone regeneration remains a challenge in tissue engineering due to the lack of highly bioactive biomaterial scaffolds. Physical structures such as nanostructures, chemical components such as silicon elements, and biological factors such as genes have shown positive effects on bone regeneration. Herein, a bioactive photoluminescent elastomeric silicate‐based nanofibrous scaffold with sustained miRNA release is reported for promoting bone regeneration based on a joint physico‐chemical‐biological strategy. Bioactive nanofibrous scaffolds are fabricated by cospinning poly (ε‐caprolactone) (PCL), elastomeric poly (citrates‐siloxane) (PCS), and bioactive osteogenic miRNA nanocomplexes (denoted PPM nanofibrous scaffolds). The PPM scaffolds possess uniform nanostructures, significantly enhanced tensile stress (≈15 MPa) and modulus (≈32 MPa), improved hydrophilicity (30–60°), controlled biodegradation, and strong blue fluorescence. Bioactive miRNA complexes are efficiently loaded into the nanofibrous matrix and exhibit long‐term release for up to 70 h. The PPM scaffolds significantly promote the adhesion, proliferation, and osteoblast differentiation of bone marrow stem cells in vitro and enhanced rat cranial defect restoration (12 weeks) in vivo. This work reports an attractive joint physico‐chemical‐biological strategy for the design of novel cell/protein‐free bioactive scaffolds for synergistic tissue regeneration.

Hybrid elastomer-plastic microfluidic device as a convenient model for mimicking the blood-brain barrier in vitro.

In this study, we fabricated a hybrid elastomer-plastic microdevice using the silicone elastomer poly(dimethylsiloxane) (PDMS) and the plastic polycarbonate (PC), to mimic the human blood-brain barrier (BBB) in vitro. Specifically, the microchannel-imprinted elastomer was first coated with 3-aminopropyltriethoxysilane to produce amine-terminated PDMS. Then, simply by conformal contact at room temperature, the amine-functionalized PDMS was bonded to pristine PC through the formation of urethane linkages. Aside from realizing device bonding, the amine functionalization also assisted in subsequent dopamine coating to form polydopamine and provide a stable surface for culturing human endothelial cells and central nervous system-related cells (e.g., astrocytes) inside the microchannels. Successful mimicking of the BBB-like microenvironment was assessed by 3D co-culturing of human endothelial cells and astrocytes, where the microdevice was verified as an acceptable in vitro BBB model according to the following four criteria: the formation of tight junctions at the cell-cell boundaries of the endothelial cells, evaluated by the expression of the tight junction marker ZO-1; the formation of actin filaments, evaluated using rhodamine phalloidin dye; low permeability, tested using the fluorescent tracer 40-kDa FITC-dextran; and good transendothelial electrical resistance (a measure of the tight junction integrity formed between the endothelial cells). The fabricated PDMS-PC microfluidic device ensured simple yet stable device sealing, and simultaneously enhanced BBB-mimicking cell attachment, thus fulfilling all major criteria for its application as a convenient in vitro BBB model.

Balanced strength and toughness improvement in polylactide (PLA)/poly(1,4-cyclohexylene dimethylene terephthalate glycol) (PCTG) blends using various compatibilizers

Generally, improving the toughness of polylactic acid (PLA) is very important for its practical applications. Blending with elastomer is considered to be the effective way for property modification of PLA. As an efficient toughener, the elastomer poly(1,4-cyclohexylene dimethylene terephthalate glycol) (PCTG) showed great potential in improving the toughness of PLA. However, the compatibility between PLA and PCTG is still a key problem. Here, the PLA/PCTG blends with various compatibilizers of SOG-02, SAG-008, and AX8900 were successfully prepared using melt compounding. The compatibility effects of SOG-02, SAG-008, and AX8900 on PLA/PCTG blends were investigated from their mechanical properties, thermal stabilities, melt flow rates, and crystallization behavior. Based on the results, SOG-02 showed the best compatibilizing effect on PLA/PCTG blends among the used compatibilizers. More importantly, it is worth noting that use of SOG-02 together with AX8900 further enhanced its compatibilizing effect on the PLA/PCTG blends with obvious improvements in mechanical properties and toughness. After blending with 3 wt% of SOG-02 and 2 wt% of AX8900, the tensile and bend strengths of PLA/PCTG/SOG-02/AX8900 were ~ 52.9 and ~ 67.2 MPa, respectively. In the meantime, the PLA/PCTG/SOG-02/AX8900 still kept benign notched impact strength (~ 6.3 MPa) and high elongation-at-break (~ 12.7%).

Patterned, Flexible, and Stretchable Silver Nanowire/Polymer Composite Films as Transparent Conductive Electrodes.

The emergence of flexible and stretchable optoelectronics has motivated the development of new transparent conductive electrodes (TCEs) to replace conventional brittle indium tin oxide. For modern optoelectronics, these new TCEs should possess six key characteristics: low cost, solution-based processing; high transparency; high electrical conductivity; a smooth surface; mechanical flexibility or stretchability; and scalable, low-cost patterning methods. Among many materials currently being studied, silver nanowires (AgNWs) are one of the most promising, with studies demonstrating AgNW films and composites that exhibit each of the key requirements. However, AgNW-based TCEs reported to date typically fulfill two or three requirements at the same time, and rare are examples of TCEs that fulfill all six requirements simultaneously. Here, we present a straightforward method to fabricate AgNW/polymer composite films that meet all six requirements simultaneously. Our fabrication process embeds a AgNW network patterned using a solution-based wetting-dewetting protocol into a flexible or stretchable polymer, which is then adhered to an elastomeric poly(dimethylsiloxane) substrate. The resulting patterned AgNW/polymer films exhibit ∼85% transmittance with an average sheet resistance of ∼15 Ω/sq, a smooth surface (a root-mean-square surface roughness value of ∼22 nm), and also withstand up to 71% bending strain or 70% stretching strain. We demonstrate the use of these new TCEs in flexible and stretchable alternating current electroluminescent devices that emit light to 20% bending strain and 60% stretching strain.

Stretching-induced Alignment of Carbon Nanotubes and Associated Mechanical and Electrical Properties of Elastomeric Polyester-based Composite Fibers

Composite fibers composed of elastomeric segmented copolyetherester (CPEE) and poly(ethylene glycol)-functionalized multi-walled carbon nanotubes (MWCNT-PEG) (80/20 by wt%) were manufactured using wet-spinning and stretched up to 200 % at room temperature. It was confirmed that the introduction of PEG chains on the surfaces of the MWCNTs provides a specific interfacial interaction between the MWCNTs and CPEE matrix, which results in an enhanced alignment of the MWCNTs in the CPEE/MWCNT-PEG composite fibers through a simple stretching at room temperature without any high-temperature conditions required for the general drawing or stretching processes. As a result, the initial modulus and tensile strength of the composite fibers stretched up to 200 % were increased by 320 % and 350 %, respectively, as compared to the as-spun composite fibers. In addition, the electrical conductivity of the composite fibers was also noticeably increased with an increase in the stretching ratio. Interestingly, the correlation coefficient among the MWCNT alignment, modulus, and conductivity is 0.97, which means that the alignment of the MWCNTs is closely related to the change in the physical properties of the composite fibers.

The Use of Platelet-Rich Plasma to Promote Cell Recruitment into Low-Molecular-Weight Fucoidan-Functionalized Poly(Ester-Urea-Urethane) Scaffolds for Soft-Tissue Engineering.

Due to their elastomeric behavior, polyurethane-based scaffolds can find various applications in soft-tissue engineering. However, their relatively inert surface has to be modified in order to improve cell colonization and control cell fate. The present study focuses on porous biodegradable scaffolds based on poly(ester-urea-urethane), functionalized concomitantly to the scaffold elaboration with low-molecular-weight (LMW) fucoidan; and their bio-activation with platelet rich plasma (PRP) formulations with the aim to promote cell response. The LMW fucoidan-functionalization was obtained in a very homogeneous way, and was stable after the scaffold sterilization and incubation in phosphate-buffered saline. Biomolecules from PRP readily penetrated into the functionalized scaffold, leading to a biological frame on the pore walls. Preliminary in vitro assays were assessed to demonstrate the improvement of scaffold behavior towards cell response. The scaffold bio-activation drastically improved cell migration. Moreover, cells interacted with all pore sides into the bio-activated scaffold forming cell bridges across pores. Our work brought out an easy and versatile way of developing functionalized and bio-activated elastomeric poly(ester-urea-urethane) scaffolds with a better cell response.