A shape memory polymer based on poly(vinyl alcohol) (SM-PVA) chemically cross-linked with glutaraldehyde exhibits good temperature responsive shape memory behavior. In the present investigation, solvent-induced shape memory behavior is observed by immersing this kind of SM-PVA in good or poor solvents (including water, DMF, and EG etc.) for PVA. A significant indication of shape memory is the decrease of the glass transition temperature (T g ), which is caused by PVA swelling in certain solvents. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), swelling equilibrium and bending tests are carried out to find the mechanism behind this interesting phenomenon. Factors that influence the permeation of solvents in the polymer depend on the rate and degree of swelling and whether swelling will occur, which determines the shape recovery ratio in different solvents. Water can induce shape recovery in a shorter time than organic solvents. The structure of water and PVA, and the interaction between them, contribute to the shorter recovery time. SM-PVA has an excellent shape recovery ratio even after several test cycles. Using solvents as a stimulus for shape memory behavior will extend applications of SMPs, especially in the field of medical devices, where stimulus instead of heat is highly desired.

Uniform hollow spheres of CoS2 have been successfully synthesized via a facile solvothermal method and electrochemically investigated as anode material for lithium-ion batteries. The key strategy is that sulfur powder is used as the sulfur source, while absolute ethanol (EtOH) serves as the solvent and reducing agent simultaneously. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) patterns demonstrate the high purity of the product. SEM images display that the hollow spheres are about 2−3 μm in diameter and 300 nm in shell thickness. The mechanism for the formation of the final hollow structure is discussed. Temperature and reaction concentrations are found to be the key factors in controlling the morphologies. Meanwhile, electrochemical measurements reveal that the as-prepared CoS2 delivers high discharge capacity (1210 mAh g−1) and good cycle stability, indicating that it might find possible application as anode material for lithium-ion batteries in the long term.

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