Silk fibroin powder and biodegradable polybutylene adipate terephthalate (PBAT)/poly lactide (PLA) blends were melt-mixed together to fabricate natural and synthetic polymers as possible new sources of biomaterials. Morphological observations conducted through scanning electron microscopy indicated poor dispersion of the silk powder agglomerates, which resulted from strong hydrogen interactions between silk powder chains in the PBAT/PLA matrix. Although the silk powder agglomerates decreased the mechanical properties, as silk powder fractions increased, the ternary blend with 10 wt % silk powder still displayed high impact strength of 108 J/m and tensile modulus of 1.2 GPa. On the basis of mechanical analysis, this blend offered potential applications in fields which required high impact strength. Blends which contained Joncryl experienced a decrease in storage modulus. Furthermore, rheological studies confirmed that the viscosity of the PBAT/PLA/Silk powder blends decreased, which indicated possible weakening of hydrogen bonds between the silk chains, caused by the reaction between the epoxy groups of Joncryl. This reaction provides a possible method to improve the processability of this natural polymer and to improve its distribution in polymer blends.

Epitaxial BiFeO 3 (BFO) thin films with striped-and single-domain structures have been grown on SrTiO 3 (STO) ( 103) and ( 113) substrates by radiofrequency planar magnetron sputtering. The domain structure of BFO was controlled by the orientation of the STO substrate. Piezoelectric force microscopy revealed that BFO thin films on STO (103) and STO (113) had a striped-domain structure with 71°domain walls running along o010p STO , and a single-domain structure, respectively. To confirm the photovoltaic property, rectangular Pt electrodes with widths of 150-200 µm were deposited on BFO surfaces with interelectrodes distances of 200-250 µm. I-V characteristics were measured under an illumination of a collimated violet laser (λ = 405 nm) with a power density of 380 W/cm 2 . In the striped-domain-structure BFO film with Pt electrodes fabricated along domain walls, above-band-gap open-circuit voltage (V OC ) of 29 V was observed. In addition, single-domain-structured BFO thin film with Pt electrodes fabricated along h 110i also showed above-band-gap V oc of 26 V despite the absence of domain walls. It is considered that these largeV oc values originated from the photovoltaic effect not at the domain walls but in bulk BFO.

Lower critical solution temperature (LCST) phase transition of glycol ether (GE)-water mixtures induces an abrupt change in osmotic pressure driven by a mild temperature change. The temperature-controlled osmotic change was applied for the forward osmosis (FO) desalination. Among three GEs evaluated, di(ethylene glycol) n-hexyl ether (DEH) was selected as a potential FO draw solute. A DEH-water mixture with a high osmotic pressure could draw fresh water from a high-salt feed solution such as seawater through a semipermeable membrane at around 10 °C. The water-drawn DEH-water mixture was phase-separated into a water-rich phase and a DEH-rich phase at around 30 °C. The water-rich phase with a much reduced osmotic pressure released water into a low-salt solution, and the DEH-rich phase was recovered into the initial DEH-water mixture. The phase separation behaviour, the residual GE concentration in the water-rich phase, the osmotic pressure of the DEH-water mixture, and the osmotic flux between the DEH-water mixture and salt solutions were carefully analysed for FO desalination. The liquid-liquid phase separation of the GE-water mixture driven by the mild temperature change between 10 °C and 30 °C is very attractive for the development of an ideal draw solute for future practical FO desalination.

Abrupt changes in effective concentration and osmotic pressure of lower critical solution temperature (LCST) mixtures facilitate the design of a continuous desalination method driven by a mild temperature gradient. We propose a prototype desalination system by circulating LCST mixtures between low and high temperature (low T and high T) units. Water molecules could be drawn from a high-salt solution to the LCST mixture through a semipermeable membrane at a temperature lower than the phase transition temperature, at which the effective osmotic pressure of the LCST mixture is higher than the high-salt solution. After transfer of water to the high T unit where the LCST mixture is phase-separated, the water-rich phase could release the drawn water into a well-diluted solution through the second membrane due to the significant decrease in effective concentration. The solute-rich phase could be recovered in the low T unit via a circulation process. The molar mass, phase transition temperature, and aqueous solubility of the LCST solute could be tuneable for the circulatory osmotic desalination system in which drawing, transfer, release of water, and the separation and recovery of the solutes could proceed simultaneously. Development of a practical desalination system that draws water molecules directly from seawater and produces low-salt water with high purity by mild temperature gradients, possibly induced by sunlight or waste heat, could be attainable by a careful design of the molecular structure and combination of the circulatory desalination systems based on low- and high-molar-mass LCST draw solutes.