Poly[oxymethylene-oligo(oxyethylene)] for use in subambient temperature electrochromic devices

Polymer electrolytes were prepared from oxymethylene-linked polyethylene gl ycol 200 with lithium perchlorate at O:Li mole ratios of 10, 25 and 70, and with zinc iodide at an O:Zn mole ratio of 70. At the higher salt concentra tions (O:Li less than or equal to 25), the electrolytes were amorphous at t emperatures down to -20 degrees C. Conductivity was measured over a range o f temperatures (eg for O:Li = 25, sigma ranged from 4 x 10(-8) S cm(-1) at -10 degrees C to 2 x 10(-4) S cm(-1) at 70 degrees C). A prototype electroc hromic device was constructed for which the progression of a colour front w as temperature dependent. Such a device could be utilized as a time-tempera ture integrating sensor for indicating whether frozen goods have been store d correctly. (C) 2000 Society of Chemical Industry.