Design And Synthesis Of Polyoxometalates/Polymer Composites And Their Application For Intelligent Catalysis

Heteropolyacids (HPAs), a large family of anionic metal–oxygenclusters of early transition metals,(also named polyoxometalates，POMs),have received increasing attention as oxidation catalysts because of their numerousadvantageous properties, such as inorganic nature, thermodynamic stability tooxidation, hydrostability, tunability of redox and acid properties. Stimuli-responsivepolymer materials are playing an increasingly important part in catalysis, as catalyticreactions can be controlled by applying appropriate stimuli (pH, heat, light, magnet,etc.). In this work, two different types of thermo-responsive catalysts were fabricatedusing molybdovanadophosphoric acid (H5PV2Mo10O40) and PNIPAM orPNIPAM-contained block copolymers, the obtained composite materials were wellcharacterized by XRD, SEM, TEM, IR, TG and nitrogen adsorption–desorption.Catalytic wet hydrogen peroxide oxidation of phenol was investigated, the catalystsshowed significant catalytic efficiency, reusability and the repeated on/off catalyticactivity switched by temperature control.1. Fabrication of molybdovanadophosphoric acids incorporated into SBA-15mesoporous silicas was achieved via a one-pot procedure. Catalytic wet hydrogenperoxide oxidation of phenol showed significant catalytic efficiency andreusability.2. A nanoreactor with thermo-responsive poly (N-isopropylacrylamide)(PNIPAM)coated on the external surface of SBA-15and molybdovanadophosphoric acids(H5PV2Mo10O40) loaded into the internal pores were fabricated. Catalytic wethydrogen peroxide oxidation of phenol indicated that the nanoreactor showed therepeated on/off catalytic activity switched by temperature control.3. Temperature responsive block copolymers composed of poly(N-isopropylacrylamide)(PNIPAM) and poly (L-lysine)(PLL) were synthesized.The self-assembly of these PLL-based copolymers induced by temperature wereinvestigated, HPAs were linked to the block copolymer via electrostatic forcebetween HPAs and amino groups. Catalytic wet hydrogen peroxide oxidation ofphenol indicated that the nanoreactor showed the notably different catalyticactivity as HPAs showed different affinity to substrate in different temperature.