Organic ferroelectrics with high dielectric constant have received substantial attention for sustainable and flexible energy storage. Here, we report a high-κ dielectric, optically transparent, mechanically strong and flexible dielectric polymer produced by in situ formation of biaxial ferroelectric-molecule-modified poly(vinyl alcohol) (PVA). The composite film was fabricated by solution casting of a PVA solution containing water-soluble dielectric crystals [Hdabco]ClO 4 . Atomic force microscopic and polarized optical microscopic studies showed a uniform dispersion of TEDA.C crystals with tunable rod-like or dendritic microstructures in the PVA matrix. Because of the good compatibility and hydrogen bonds between PVA and TDEA.C, the modified PVA films presented a significant enhancement of the dielectric constant and energy storage density by 10−100-fold over neat PVA. The polarization-electric loops indicated that the PVA composite films possessed increased saturation polarization in comparison to neat PVA film. The remnant polarization of PVA composite films was improved by around 3200 times with 9 wt % TEDA.C. Also, the TEDA.C@PVA films exhibited 85% transparency throughout the visible spectrum, 116% increase in storage modulus, and 274% elongation at fracture. These unprecedented high-κ dielectric, optical, and mechanical properties may break the restrictions in the applications of traditional ferroelectric materials and greatly expand the usage of dielectric polymers in broad fields.

No abstract

No abstract

Highly efficient and regioselective synthesis of pharmacologically interesting aromatic esters of arbutin catalyzed by immobilized lipase from Penicillium expansum in cosolvent systems was successfully carried out. As compared to tetrahydrofuran solvent, the initial rate and substrate conversion of arbutin vanilylation were markedly enhanced in tetrahydrofuran-isopropyl ether (20%, v/v). Moreover, the effects of three reaction parameters (enzyme amount, temperature and substrate molar ratio of vinyl vanillic acid to arbutin) on 6-O-vanilloyl-arbutin synthesis were scrutinized and the key process parameters were optimized using response surface methodology (RSM). The experimental data were fitted well to a second order polynomial model by using multiple regression analysis. The best combination of variables was 50 • C, 93 U/mL and 11 for the reaction temperature, the enzyme amount and mole ratio of arbutin to vinyl vanilic acid, respectively, and which the reaction rate, substrate conversion and regioselectivity were as high as 8.2 mM/h, 93 and 99%. It was worth noting that a variety of aromatic esters of arbutin were obtained with much higher conversion (93-99%) at these optimal conditions.