Search

Hydrophilic macroporous sponge has been widely used in solar steam generation, catalysis, biosensing and other fields due to its high water transporting and adsorption ability. However, the synthesis step of hydrophilic sponge usually needs the assistance of a freezing process and toxic chemicals such as chemical crosslinkers or foaming agents. To solve these problems, herein, a novel and facile tactic based on the salting out effect was proposed to prepare hydrophilic amphibious open-cell macroporous sponge from the poly(vinyl alcohol) (PVA) solution. Glycerol, CaCl2 and Na3Cit were successively added into PVA solution. The sol–gel transition would occur due to the salting-out effect of Na3Cit and hydrogen bond crosslinking of glycerol. Finally, the hydrophilic PVA sponge with different shapes and sizes could be easily prepared. Moreover, this hydrophilic wet sponge could be room temperature dried into dry sponge and this dry sponge could be quickly restored to wet sponge after immersing in water due to its ultra-rapid water absorption. The microstructure and mechanical properties of PVA wet and dry sponges were studied. The PVA wet sponge showed excellent mechanical properties with a tensile strength, Young's modulus, and fracture energy of 1.51 ± 0.01 MPa, 0.44 ± 0.02 MPa, and 113.2 ± 1.6 kJ m−2, respectively. The wet sponge prepared in this work has an average porosity of up to 50 μm, and the pore structure can still be maintained during the conventional room temperature drying process. Moreover, the PVA sponge showed high stability in various aqueous media including acid, alkaline, and salt solutions. This work provided a simple and large-scale method to prepare amphibious open-cell hydrophilic PVA sponge. [ABSTRACT FROM AUTHOR]

To engineer tissue restoration, it is necessary to provide a bioactive, mechanically robust scaffold. Electrospun poly(i-caprolactone) (PCL) nanofiber is a promising biomaterial candidate with excellent mechanical properties, but PCL scaffolds are inert and lack natural cell recognition sites. To overcome this problem we investigated the incorporation of Antheraea pemyi silk fibroin (ASF) containing inherent RGD tripeptides with PCL in electrospinning process. The mixing ratios showed remarkable impact on the properties of hybrid nanofibers. Increasing PCL content significantly enhanced the mechanical properties of nanofibers. In particular, the mechanical properties were remarkably enhanced when PCL content increased from 50 wt% to 70 wt%. Moreover, the biological assays based on endothelial cells showed promoted cell viability when ASF content reached to 30 wt%. The data demonstrated that the nanofiber containing 70% of PCL and 30% of ASF achieved the most balanced performances for integrating the mechanical properties of PCL and the bioactivity of ASF. Furthermore, biomimetic alignment of 70PCL/30ASF nanofibers was achieved, which could support PC12 neuron-like cell growth and guide neurite outgrowth, providing a potentially useful option for the engineering of oriented tissues. The results show that the PCL/ASF hybrid nanofibers can be considered as a promising candidate for tissue engineering scaffolds. POLYM. ENG. SCI., 57:206-213, 2017. [C] 2016 Society of Plastics Engineers, INTRODUCTION Appropriate biomaterial scaffolds for tissue engineering should be designed such that they can improve cell growth and guide tissue regeneration. To engineer tissue restorations, it is necessary to control [...]

Fiber-reinforced polymer matrix composites during engineering applications can be influenced by critical environmental conditions (e.g., water and temperature), probably causing a negative impact on the mechanical performance. In this work, the hygrothermal aging behavior and flexural property of carbon fiber (CF)-reinforced polyethylene terephthalate glycol (PETG) composites were investigated at different aging temperatures and days. The CF/PETG composites were fabricated using the hot-press molding method. The mathematical fitting model and finite element analysis method were employed to reveal the hygrothermal aging behavior and the moisture absorption evolution. After 90 days of aging, the water uptakes of the specimens at 25°C, 45°C, and 60°C are 0.55%, 0.62%, and 1.67% for PETG and 0.47%, 0.54%, and 1.52% for CF/PETG, respectively. The flexural strengths of the CF/PETG composites at 25°C, 45°C, and 60°C after 90 days of aging decrease by 28.6%, 30.2%, and 32.2% as compared with the non-aging composites, respectively. The water uptakes of the CF/PETG composites tend to increase with the increase in cyclic aging time interval. The flexural strengths of the composites with the cyclic aging intervals of 2, 5, 10, and 15 days first decrease and then increase slightly. The knowledge gained in this study will benefit future design optimization of the CF/PETG composite material and lay the foundation for its engineering application. [ABSTRACT FROM AUTHOR]

Poly(vinyl alcohol) (PVA) films modified with Magnesium chloride hexahydrate (Mg[Cl.sub.2] * 6 [H.sub.2]O) were prepared by casting method. The prepared films were characterized by X-ray diffraction measurements (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and mechanical testing. It was found that the presence of Mg[Cl.sub.2] * 6 [H.sub.2]O had considerable effects on the crystallinity, thermal, and mechanical properties of PVA films. The crystallization of PVA film was interrupted and the degree of crystallinity of PVA film decreased with the addition of Mg[Cl.sub.2] * 6[H.sub.2]O. The glass transition temperature of PVA film decreased with the addition of Mg [Cl.sub.2] * 6[H.sub.2]O. After modifying with Mg [Cl.sub.2] * 6[H.sub.2]O, PVA film became soft, with lower tensile strength and higher elongation at break. The presence of Mg[Cl.sub.2] * 6 [H.sub.2]O could significantly increase the moisture content of PVA films and this may be the cause of the plasticizing. POLYM. ENG. SCI., 52:1565-1570, 2012. [C] 2012 Society of Plastics Engineers, INTRODUCTION Polymeric materials made from petroleum have been widely used throughout the world. However, a great majority of these products are disposed off into the environment after usage. Clearly, this [...]

Continuous real-time human motion and heart-rate monitoring systems can provide vital clinical information for disease diagnosis, preventive healthcare and rehabilitation care. However, it is still a challenge to design wearable pressure/strain sensors with great flexibility and sustainable power for motion detection and physiological signal monitoring. Here, a self-powered laminated fabric sensor based on Schottky contact was successfully fabricated. This laminated fabric sensor was constructed by sandwiching the polypyrrole (PPy)-coated fabric with the Ni-coated fabric and Al plastic film. The electrical outputs under strain were attributed to the single Schottky contact between PPy and Al. This fabric sensor exhibited excellent stability under continuous quick cycling operation and at high relative humidity, which could be adapted to different human body parts for continuous motion detection and heart-rate monitoring. This work is of great significance to demonstrate a promising strategy toward self-powered wearable pressure sensors used for human motion detecting and hear-rate monitoring. [ABSTRACT FROM AUTHOR]