To demonstrate the effect of donor (D) and acceptor (A) units on the structure-property relationships of electrochromic polymers, design, synthesis, characterization and polymerization of a series of D-A type systems, 1-5, based on thiophene, 3,4-ethylenedioxythiophene, and 3,3didecyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine as D units and 2,1,3-benzoselenadiazole, 2,1,3benzothiadiazole and 2-decyl-2H-benzo [d][1,2,3]triazole as A units are highlighted. It is found that these units play key roles on the redox behavior, band gap, neutral state color, and the electrochromic performance (stability, optical contrast, coloration efficiency, and switching time) of the system. It is noted that electropolymerization of these D-A systems provides processable low band gap electrochromes, P1-P5, exhibiting high redox stability, coloration efficiency, transmittance and/or contrast ratio and low response time. Furthermore, P1-P5 reflect various hues of blue and green pallets of the RGB color-space in the neutral state. In particular, it is noteworthy that P5 is an excellent blue-to-colorless polymeric electrochrome, which, to our best knowledge, exhibits the highest optical contrast and coloration efficiency among the D-A type systems. The panoramic breadth of the neutral state colors and intriguing features of these polymeric materials further confirm that D-A approach allows engineering tunable electrochromes, which hold promise for commercialization of polymeric RGB electrochromics.

No abstract

No abstract

BACKGROUND: Microsphere and/or hollow sphere formation of methyl-substituted polyaniline derivatives was investigated via chemical polymerization where different sets of conditions were examined. It was found that a variety of parameters (e.g. types and concentrations of monomer and oxidant, polymerization time, solvent with and without acid) have a crucial influence on the morphology of the resulting polyaniline derivatives. RESULTS: Structures with desired morphologies (with or without microspheres and hollow spheres) may be obtained in a controlled manner by changing the parameters. Moreover, the electrochemical and optical properties of the polymers in the presence of acid and/or base were investigated via cyclic voltammetry and UV-visible and electron spin resonance spectroscopic techniques. It is noteworthy that the morphologies of microspheres and/or hollow spheres remained unchanged after repeated acid and base treatments.CONCLUSION: Micro/hollow spherical structures were successfully prepared via chemical polymerization of various substituted anilines by using ammonium persulfate as oxidant. It was found that the type of oxidant and monomers along with the polymerization time are quite important factors for the formation of micro/hollow spheres. Furthermore, hydrogen bond formation does not play any crucial role for the formation of these spheres. Chemically and electrochemically doped/dedoped states of microspheres and/or hollow spheres are very sensitive, and give rapid response towards vapours of HCl and NH 3 , which makes them amenable for use in sensors.