A stretchable and multicolor electrothermal chromatic fiber is prepared based on reduced graphene oxide (RGO) functionalized elastic conductive fibers and various thermochromic materials. The colors of the fibers can be switched within 15s due to the good resistive-heating performance of the conductive fibers. Through a combination of different thermochromic materials, abundant and reversible color changes are clearly observed by the naked eye (e.g., from orange, red, green to yellow, purple, blue and white, respectively). Moreover, the fibers exhibit excellent color changing stability even after 1000 resistive-heating or stretching/releasing cycles owing to the structural stability of the multilayered fibers and the excellent electrothermal stability of RGO. Finally, they are easily woven into textiles and plaited into colorful hand chains, which showed huge application value especially for stretchable visual sensors and clothing integrated wearable displays.

Flexible actuators are widely in demand for many real-life applications. Considering that existing actuators based on polymers, low-dimensional materials and pore-rich materials are mostly limited by slow response rate, high driving voltage and poor stability, we report here a novel metal based flexible actuator which is fabricated simply through partial oxidation and nano-function of copper foil with the assistance of reduced graphene oxide. The obtained asymmetric metallic actuator is (electric-)thermally driven and exhibits fast response rate (∼2 s) and large curvature (2.4 cm−1) under a low voltage (∼1 V) with a sustainable operation of up to ∼50 000 cycles. The actuator can also be triggered by infrared irradiation and direct-heating under various conditions including air, water, and vacuum.

Many efforts have been devoted to fabricating three-dimensional graphene-derived aerogels owing to their promising real-world applications. However, it is still a challenge to fabricate a pure graphene-based aerogels with both high mechanical strength and conductivity. In this study, we report a facile and scalable method to prepare pure chemically converted graphene aerogels (CCGA) from high-concentration gel precursors with the assistance of two-step freeze-drying. The CCGA demonstrates a high compressive strength of 106.1 kPa under a strain of 80%. Its resistance in the thickness direction is variable and reaches as low as 6.6 Ω at a compressive strain of 90%. The aerogels also show many interesting behaviors and properties, including promising Joule heating-assisted oil absorption, non-flammability, and the ability to sense a wide range of applied pressure.Download high-res image (418KB)Download full-size image

Engineering traditional materials into the new form of atomic and free-standing two-dimensional structures is of both fundamental interest and practical significance, but it is in general facing challenges especially for metal oxide semiconductors. We herein report an ultragreen method for the cost-effective and fast preparation of atomic metal oxide nanosheets that can be further transformed into nanofilms. The method combines top-down building block synthesis and bottom-up electrophoretic assembly in water under ambient conditions, using only bulk metal and Milli-Q water without involving any additional reagents. The focus is on free-standing polycrystalline ZnO nanosheets that can be produced with a lateral dimension as large as 10 μm and a thickness of 1 nm (the thinnest free-standing metal oxide nanosheet ever reported). A new electrophoretic assembly mechanism dominated by intrinsic surface polarity was revealed. We also demonstrate potential applications of this approach for wet electronic systems as exemplified by facile and in situ fabrication of dielectric layers and cellular electrets.

Flexible and multifunctional sensors that continuously detect physical information are urgently required to fabricate wearable materials for health monitoring. This study describes the fabrication and performance of a strong and flexible vessel-like sensor. This electronic vessel consists of a self-supported braided cotton hose substrate, single-walled carbon nanotubes (SWCNTs)/ZnO@polyvinylidene fluoride (PVDF) function arrays and a flexible PVDF function fibrous membrane, and it possesses high mechanical property and accurate physical sensing. The rationally designed tubular structure facilities the detection of the applied temperature and strain and the frequency, pressure, and temperature of pulsed fluids. Therefore, the flexible electronic vessel holds promising potential for applications in wearable or implantable materials for the monitoring of health.