Transient Photodegradability of Photostable Gel Induced by Simultaneous Treatment with Acid and UV–Light for Phototuning of Optically Functional Materials

Abstract

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.

Fabrication of Photoprocessable Materials via Photopolymerization Using an Acid‐Induced Photocleavable Platinum‐Acetylide Crosslinker

“…The cleavage of the crosslinkers was visualized by the emission spectra of the gel. The Pt−C bond cleavage of the platinum–acetylide crosslinker generated a fluorescent chloroalkyne moiety, [41] changing the luminescent features from yellow phosphorescence to blue fluorescence. After the removal of HCl for cooperative photoprocessing, the processed gel regained photostability to UV light, which allowed the observation of luminescent properties.…”

Fabrication of Photoprocessable Materials via Photopolymerization Using an Acid‐Induced Photocleavable Platinum‐Acetylide Crosslinker

“…The cleavage of the crosslinkers was visualized by the emission spectra of the gel. The PtÀ C bond cleavage of the platinum-acetylide crosslinker generated a fluorescent chloroalkyne moiety, [41] changing the luminescent features from yellow phosphorescence to blue fluorescence. After the removal of HCl for cooperative photoprocessing, the processed gel regained photostability to UV light, which allowed the observation of luminescent properties.…”

“…A platinum-acetylide complex (1) bearing a supramolecular structure with permethylated α-cyclodextrin (PM α-CD) [37][38][39][40] exhibited acid-induced reactivity under UV light (Figure 2a). [41] PM α-CDs were introduced for steric protection of platinum-acetylide complexes from π-aggregation and protonation, improving the uniformity and stability of the complexes in the polymer materials. [41,42] The PtÀ C bond of 1 was cleavable in a 0.2 M HCl solution with dimethylformamide (DMF)/H 2 O (98/2, v/v) and 365 nm UV irradiation (Condition A).…”

Polymer Degradation by Synergistic Dual Stimuli: Base Interaction and Photocatalysis to Unlock a Boron Pendant Trigger for Main-Chain Scission

“…The single-stimulus-triggering system may be at risk of undesired degradation in use. In this work, we propose synergistic dual stimuli-responsive main-chain degradation designed by the introduction of a carbon–boron (C–B) bond as the trigger while ensuring polymer stability (Figure A). , …”

“…In this work, we propose synergistic dual stimuli-responsive main-chain degradation designed by the introduction of a carbon−boron (C−B) bond as the trigger while ensuring polymer stability (Figure 1A). 10,11 Boron is one of the semimetal elements that can form stable covalent bonds with carbon thanks to its relatively high electronegativity. 12 Despite its stability, C−B bonds in organoboron compounds can become useful for synthetic transformation via borate formation through interaction with a base, as well-known in organic chemistry.…”