Light‐responsive reversible two‐way shape memory polymers (2W‐SMPs) are highly promising for many fields due to indirect heating, clean, and remote control. In this work, a composite with both thermal‐ and near‐infrared (NIR) light‐induced reversible two‐way shape memory effect (2W‐SME) is prepared by doping extremely little quantities of 2D non‐layered molybdenum dioxide nanosheets (2D‐MoO2) into semicrystalline poly(ethylene‐co‐vinyl acetate) (EVA) networks. This is the first report on light‐induced reversible two‐way shape memory composites employing 2D‐MoO2 as photothermal fillers. Upon switching the NIR light on and off, due to the excellent photothermal feature and stability of 2D‐MoO2, the composite exhibits remarkable light‐induced reversible 2W‐SME. A light‐driven actuator for sensing applications is designed based on the composite and the circuit, where the lamp acting as an alarm can raise and fade upon responding to NIR light. A completely flexible, fuel‐free self‐walking soft robot is designed based on the advantages of the light‐responsive reversible 2W‐SMPs. Additionally, the composite acting as a light‐fueled crane is able to lift and lower a load that is 3846 times its own weight. The results demonstrate that the prepared composite has a promising prospect for applications as actuators, self‐walking soft robot and crane.
Polyurethanes are commonly used as shape memory materials due to their micro‐phase separation structure. The degree of micro‐phase separation is the key factor in the shape memory properties of materials. In this study, the shape memory polyurethane (SMPU) elastomer was prepared based on polycaprolactone diols, isophorone diisocyanate, and 1, 4‐butanediol. And the branched structure is introduced by glycerol and hexamethylene diisocyanate to increase the degree of micro‐phase separation. Moreover, nano‐ZnO is also used to enhance micro‐phase separation. Atomic force microscopy images clearly show that the nano‐ZnO disperses uniformly in the polymer matrix and leads to significant change in the phase structure of SMPU. Dynamic mechanical analysis results indicate that the SMPU/ZnO nanocomposites possess two phase transition above 0°C, one is the melting transition of the soft segments, which is near the body temperature, and the other is the glass transition of hard segments. And with the addition of nano‐ZnO, the difference in transition temperature between the hard and the soft segments is significantly increased. The relationship between shape memory properties and the micro‐phase separation is explored and discussed. In vitro biocompatibility studies show that the SMPU/ZnO nanocomposites have good biosafety. Therefore, the obtained bionanocomposites have the potential application prospect as smart biomaterials.
Ceramic
fuel cells with Gd0.1Ce0.9O1.95 (GDC)
as an electrolyte and Ni0.8Co0.15Al0.05LiO2 (NCAL)-coated foam Ni as a symmetric electrode
are prepared. The effect of initial reduction temperature of the NCAL
anode on the performance of the cells is investigated. When the initial
test temperatures of the three cells were 550, 500, and 450 °C,
respectively, the maximum power densities of the three cells at 450
°C were 0.221, 0.125, and 0.02 W·cm–2,
respectively. At 450 °C, the ionic conductivities of the electrolytes
in the cells with three different initial reduction temperatures were
0.288 (550 °C), 0.165 (500 °C), and 0.011 S·cm–1 (450 °C), respectively. During the test, LiOH/Li2CO3 produced by H2 reduction of the
NCAL anode diffuses into the GDC electrolyte, and the interface between
LiOH/Li2CO3 and GDC becomes the main channel
of ion conduction. The scanning electron microscopy, X-ray photoelectron
spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction
results indicated that the amount and the diffusion rate of the LiOH/Li2CO3 mixture diffused into the GDC electrolyte increased
with the increase of initial reduction temperature. The LiOH/Li2CO3 mixture entering into the electrolyte will
directly affect the effective area or the length of the ion conduction
channel formed by the LiOH/Li2CO3 mixture and
GDC in the electrolyte, thus significantly affecting the electrochemical
performance of the cells.
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