New flexible methylsilsesquioxane (MSQ) aerogels have been facilely prepared by a sol–gel process with methyltrimethoxysilane (MTMS) and dimethyldimethoxysilane (DMDMS) as co-precursors, followed by surface modification and ambient pressure drying. The microstructure, mechanical properties and hydrophobicity of these MSQ aerogels after surface modifications of hexamethyldisiloxane (HMDSO) and/or hexamethyldisilazane (HMDS) were investigated in detail, and the applications of surface-modified MSQ aerogels in sound-absorbance, fast dye adsorption and oil/water separation were evaluated, respectively. The MSQ aerogels surface-modified by HMDS possess flexibility, elasticity and superhydrophobicity, and demonstrate good performance in the mentioned applications. The resultant MSQ aerogel used in sound-absorbance has high frequency (about 6 kHz) acoustic absorptivity of up to 80%, benefiting from its macroporous structure and porosity of 94%, and it also possesses intermediate frequency acoustic absorptivity (about 1 kHz) up to 80% owing to its elasticity. This MSQ aerogel can selectively separate oil from oil/water mixtures with high efficiency due to its superhydrophobicity and superlipophilicity, resulting from a lot of methyl groups, density as low as 0.12 cm3·g−1 and a water contact angle as high as 157°. This MSQ aerogel can be assembled to be a monolithic column applied for fast dye adsorption, and shows selective adsorption for anionic dyes and removal efficiency of methyl orange of up to 95%.
Stretchable resistive sensors attract wide attention due to their feasible fabrication method and promising application prospect, while the sensitivity (gauge factor (GF)) and response time for quick and effective response in working are very important for stretchable resistive sensors. Herein, a facile method combined with solution coating and laser direct writing is promoted to fabricate a silver nanowire/silver/poly(dimethylsiloxane) (AgNW/Ag/PDMS) strain sensor. The reduced Ag welds the AgNWs to make the conductive layer robust for deformation, and the obtained stretchable resistive sensor has a high GF of 623.2, a short response time of 51 ms, a recovery time of 50 ms, a wide sensing range beyond 35%, and good cyclic repeatability (over 2000 times). The sensor features highly sensitive and stable performance for monitoring diverse human and mechanical motions, demonstrating a promising and attractive application for wearable devices and human–machine interaction.
Wounds in diabetic patients, especially diabetic foot ulcers, are more difficult to heal compared with normal wounds and can easily deteriorate, leading to amputation. Common treatments cannot heal diabetic wounds or control their many complications. Growth factors are found to play important roles in regulating complex diabetic wound healing. Different growth factors such as transforming growth factor beta 1, insulin-like growth factor, and vascular endothelial growth factor play different roles in diabetic wound healing. This implies that a therapeutic modality modulating different growth factors to suit wound healing can significantly improve the treatment of diabetic wounds. Further, some current treatments have been shown to promote the healing of diabetic wounds by modulating specific growth factors. The purpose of this study was to discuss the role played by each growth factor in therapeutic approaches so as to stimulate further therapeutic thinking.
Methylsilsesquioxane (MSQ) aerogels with uniform mesopores were facilely prepared via a sol–gel process followed by microwave drying with methyltrimethoxysilane (MTMS) as a precursor, hydrochloric acid (HCl) as a catalyst, water and methanol as solvents, hexadecyltrimethylammonium chloride (CTAC) as a surfactant and template, and propylene oxide (PO) as a gelation agent. The microstructure, chemical composition, and pore structures of the resultant MSQ aerogels were investigated in detail to achieve controllable preparation of MSQ aerogels, and the thermal stability of MSQ aerogels was also analyzed. The gelation agent, catalyst, solvent, and microwave power have important roles related to the pore structures of MSQ aerogels. Meanwhile, the microwave drying method was found to not only have a remarkable effect on improving production efficiency, but also to be conducive to avoiding the collapse of pore structure (especially micropores) during drying. The resulting MSQ aerogel microwave-dried at 500 W possessed a specific surface area up to 821 m2/g and a mesopore size of 20 nm, and displayed good thermal stability.
Silver nanowire transparent conductive films (AgNW TCFs) were facilely prepared by screen printing conductive ink on a polyethylene terephthalate (PET) substrate, and the effects of ink compositions and oily stencil on the optoelectrical properties of AgNW TCFs were investigated in detail. 7.3 mg·mL-1 hydroxypropyl methylcellulose (HPMC), 4.12 mg·mL-1 AgNWs and 98T oily stencil allow the preparation of large-scale AgNW TCFs with high transmittance, low square resistance and high uniformity. The resultant screen printed AgNW TCFs possesses a sheet resistance as low as 13.0±0.6 Ω/sq, a transmittance of about 95.3% at 550 nm wavelength (deducting the background) and a haze of 3.86 (deducting the background), and can achieve a surface root mean square roughness of 3.33 nm, a film size of 15×20 cm2 and personalized pattern by means of the screen printing process. The transparent film heater (TFH) constructed by AgNW TCFs can rise to a usable temperature of 55°C at a low voltage of 4 V within 80 s. This process provides a simple strategy for fabricating uniform, patterned and large size AgNW TCFs for various devices.
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