A new application of Krafft point concept: an ultraviolet-shielded surfactant switchable window

We report thermo-responsive gels of polyacrylamide (PAAm) with ionic surfactants in mixed water and ethylene glycol (W-EG) solvents as smart windows to solubilize ultraviolet absorbents for UV shielding materials. The Krafft point (T-K) of the ionic surfactants determines the phase transition that switches the transparency and opacity of the gels. The T-K can be flexibly tuned within a wide temperature range (6-75 degrees C) with high predictability by changing the surfactant or adjusting the ratio of W-EG solvents.