Grafting triphenylamine groups onto polysiloxanes to improve interaction between the electrochromic films and ITO

A novel series of triphenylamine (TPA)-contained polysiloxanes (PTPASi) have been synthesized by a normal reaction of hydrosilylation through poly(methylhydrosiloxane)(PMHS) with four TPA-based alkenes (TPAA) for electrochromic applications. Grafting TPA onto polysiloxanes was employed as a strategy to ameliorate the thermal stability and cycle stability of the electrochromic properties due to the enhanced force of adhesion between the polymer films and the ITO substrate. The morphology and impedance of the polymers after electro-oxidizing reaction was studied and didn't reveal significant change suggesting good stability of the hybrid system. Meanwhile, with the introducing of the polysiloxane backbones, the four polymer films appeared nearly colorless in their natural state, in contrast to three primary colors of red, green and blue in their oxidized state. Hence, these PMHS films can be mixed to obtain all the other colors on the basis of the color mixing theory. In addition, the potential switching properties of the four polymers at the temperature of 150 °C have been investigated for the first time, which indicate high thermal stability and potential for relatively high temperature and/or long term cycling applications.