Electron Transfer to Anionic Reactants Incorporated within Polycationic Coatings on Glassy Carbon Electrodes. Comparison of Random and Block Copolymers

摘要

Block and random copolymers containing varying ratios of styrene and p-(diethylaminomethyl)styrene were synthesized and used to coat glassy carbon electrodes. In acidic electrolytes the coatings become polycationic and incorporated electroactive ions such as Fe(CN)(4-6)by anion exchange. With ratios of styrene to (aminomethyl)styrene groups up to ca. 2:1, the electrochemical responses exhibited by incorporated anions are very different in coatings prepared from random and block copolymer coatings of the same composition. As the quantity of protonated amino groups in the copolymer coatings increases, the electrochemical behavior of incorporated anions becomes more similar. The contrasting electrochemical behavior appears to originate in differences in the size of, and connections between, hydrophilic domains that are formed spontaneously within the coatings. Diffusion coefficients of the incorporated anions decrease sharply with the total quantity incorporated.