No abstract

No abstract

Control over both color and transparency is reported for the thermochromic materials presented here. Dyes such as Bromothymol Blue (BB) can reversibly change color with temperature when embedded in aqueous polyether/LiCl gel networks. The Figure shows a gel containing BB at room temperature (green, transparent) and at 33 °C (yellow, transparent). At 36 °C the gel becomes milky.

and its analysis were obtained through the kindness of Mr. C. A. Sluhan of the American Cyanamid and Chemical Corporation.

The effect of the addition of a zwitterionic sulfobetaine to a dye-containing polymer gel composed of two polymers - poly(vinyl alcohol) (PVA) and polyether - was investigated. With increasing sulfobetaine content a remarkable reduction of the UV-vis-absorption intensity of the longest wavelength absorption band of Phenol Red in the aqueous polymer network was observed, even for sulfobetaine concentrations below its critical micelle concentration (CMC). It can be assumed that this effect is based on the formation of ionic complexes between dye molecules and either single sulfobetaine molecules or aggregates of sulfobetaine. Furthermore, thermotropic behavior occurs in the investigated polymer gel system even at a polyether concentration as low as 0.8 wt%