Green and Blue Electrochromic Polymers from Processable Siloxane Precursors

2013-07-23T00:00:00Z (GMT) by Ki-Ryong Lee Gregory A. Sotzing
Herein we report the synthesis of a new class of processable siloxane precursor polymers consisting of aromatic groups and flexible siloxane linkages and their conversions to green and blue electrochromic polymers in the solid state. 3,4-Ethylenedioxythiophene (EDOT), 2,2′-bis­(3,4-ethylenedioxythiophene) (BiEDOT), and a donor–acceptor moiety 4,7-bis­(EDOT)-2,1,3-benzothiadiazole (BEBTD) were incorporated as aromatic groups to demonstrate the versatility of the precursor method to different aromatic systems. The utilization of a siloxane linkage allows for a precursor polymer exhibiting improved solubility in common organic solvents and accessible glass transition temperatures (−1 to 132 °C) as compared to a previously reported silane precursor. A simple method to control the thermal properties of the precursor was also demonstrated by incorporation of both siloxane and silane functionalities into the precursor backbone. The oxidatively converted product from the precursors showed electronic and optoelectronic properties comparable to the conjugated polymer prepared by conventional electrochemical polymerization of monomers in an electrolyte bath. In addition to the dark-blue to sky-blue electrochromic PEDOT from EDOT and BiEDOT, a dual-band absorbing green to sky-blue electrochromic polymer was demonstrated using BEBTD. This demonstrates that the precursor approach is easily applicable and feasible for the preparation of conjugated polymers from numerable electrochemically polymerizable aromatic groups.