Functional capsule membranes. Part 28. A capsule membrane grafted with viologen-containing polymers as a reactor of electron-transfer catalysis in heterophases

Abstract

Large, ultrathin nylon capsule membranes surface-grafted with viologen-containing polymers [poly(C_nV²⁺); n= 3, 6, and 10] were prepared. The viologen polymers acted as an effective electron-transfer catalyst in heterophases: the debromination of meso-1,2-dibromo-1,2-diphenylethane and the reduction of azobenzene in the inner organic solution of the capsule with excess of sodium dithionite in the outer aqueous solution was largely accelerated by the poly(C_nV²⁺) polymers grafted on the capsule membrane. The reaction rates increased with increasing spacer chain length (C_n) of the grafted poly(C_nV²⁺). The efficiency of electron-transfer catalysis was also influenced by the graft amount of poly(C_nV²⁺) on the capsule surface and by the ionic strength of the outer aqueous phase.