a b s t r a c tWe proposed to combine a polarized mineral tourmaline and TiO 2 nanosemiconductor to form a hybrid photocatalyst, to simultaneously optimize the photocatalytic efficiency and macroscopic aggregation of nano-TiO 2 . Photoactivity assessment toward bisphenol A (BPA) degradation indicated the optimal T(20%)-TiO 2 catalyst exhibited higher performance than the bare TiO 2 or the mechanical mixtures. In view of the reactive species scavenging results and intermediate identification, a hydroxyl radical-initiated oxidation as the dominating BPA decomposition pathway was proposed. The results of photoluminescence spectra and photocurrent measurements along with electrochemical impedance spectra and Mott-Schottky analyses led us to a better understanding of the photocatalytic process involving the facilitated charge transfer and higher carrier density induced owing to tourmaline incorporation. The synergistic effects in tourmaline-involved photocatalysis would be attributed to the fact that the internal dipolar field, originating from tourmaline spontaneous polarization, resulted in spatially varied energy levels of the bands and changed band bending of TiO 2 semiconductor, which lowered the potential barrier for photoelectrons or holes to readily migrate to the surface and retarded electron-hole recombination. The concept of engineering internal field in heterogeneous photocatalysis using a polarized mineral of low cost will shed new light on applied photochemistry and development of nanotechnology enabled approaches for water treatment.

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Salt-induced self-assemblies of poly(ethylene glycol-block-spiropyran methacrylate) (PEG-b-PSPMA) block copolymers were studied in this research. PEG-b-PSPMA block copolymers were dissolved in a 10 : 1 N,N-dimethyl-formamide (DMF)/water mixture. Upon ultraviolet light (UV) irradiation, the pendant spiropyran (SP) groups in the PSPMA blocks were isomerized into open merocyanine (MC) forms and the addition of inorganic salts (CuCl2, FeCl3 and Zn(CH3COO)2) induced micellization of PEG-b-PSPMA block copolymers in the solutions. In a salt-induced micelle, complexes formed by PSPMA and inorganic ions are in the cores and PEG chains are in the coronae. The reverse conversion of the isomers from MC form to SP form in the dark was studied by UV-vis, and the self-assembled aggregates were analyzed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The self-assembly of PEG-b-PSPMA in aqueous medium was also investigated. In aqueous solution, amphiphilic PEG-b-PSPMA self-assembled into micelles with the hydrophobic PSPMA blocks in the cores and the hydrophilic PEG blocks in the coronae. Upon UV irradiation, the hydrophobic SP units in the cores were isomerized into hydrophilic MC forms. The MC isomers have the attractive MC-MC interactions, and the reversion from MC to SP in the dark is difficult. DLS and TEM results both demonstrated that the micelles self-assembled by PEG-b-PSPMA did not disassemble upon UV irradiation, due to the attractive MC-MC interactions in the cores.

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