Although photodegradability is promising for on‐demand tuning of material properties, phototuned materials cannot be utilized under ambient light irradiation owing to their photoinstability. Herein, a novel photostable gel that photodegrades only in the presence of an acid is fabricated. The unique reactivity of a supramolecular platinum‐acetylide complex is uncovered to incorporate into poly(methyl methacrylate) gel as the cross‐linker to exhibit softening and swelling under simultaneous treatment with UV‐light and acid. Conversely, when the acid is removed, the gel reacquires its photostability. A cross‐linker amount of only 0.7 wt.% is sufficient to realize the material property. Notably, the unique cross‐linkers, which change phosphorescence to fluorescence via photocleaving of PtC bonds, enable a photoprocess of optical functions. The controllable optical properties can be applied to information hiding technology and in visualizing the locally modified elasticity of the material, because of the photostability in absence of the acid.

The modulation of molecular interaction with a [3]rotaxane structure enabled a luminescent thermoresponse with high sensitivity over a wide temperature range. Herein, a pyrene moiety was encapsulated by permethylated α-cyclodextrins and was introduced into a polymer network material of poly(vinyl alcohol) as a cross-linker. The luminescence nature associated with the pyrene moiety was continuously switched from a static pyrene−pyrene excimer emission mode at 193 K to a dynamic pyrene−dimethylaniline (DMA) exciplex emission mode at 293 K. A series of [3]rotaxane structures revealed the impact of supramolecular control of the interaction among pyrenes and DMA. Consequently, the continuously coupled two luminescent modes of pyrene (excimer and exciplex) provided a monotonical luminescence change over a wide temperature range (100 K) with high sensitivity of the wavelength variation (0.64 nm/K) as a distinguished thermoresponsive material to visualize the thermal information.

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