Reversibly Softening and Stiffening Organogels Using a Wavelength-Controlled Disulfide-Diselenide Exchange

Area of Science:

• Polymer Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Dynamic covalent bonds offer tunable material properties.
• Light-responsive materials are crucial for advanced applications.
• Organogels require robust and reversible crosslinking mechanisms.

Purpose of the Study:

• To synthesize light-responsive organogels using wavelength-dependent seleno-sulfide dynamic covalent bonds.
• To investigate the reversible changes in organogel stiffness upon light irradiation.
• To explore the potential of this chemistry for functional materials.

Main Methods:

• Preparation of disulfide cross-linked organogels from poly(ethylene glycol) and poly(methacrylate) copolymers.
• Utilizing 5,5'-diselenide-bis(2-aminobenzoic acid) for disulfide-diselenide exchange reactions.
• Employing UV and visible light irradiation to cleave and reform seleno-sulfide and disulfide bonds, respectively.
• Measuring changes in storage modulus (G') to quantify stiffness variations.

Main Results:

• Successful preparation of organogels with reversible stiffness changes triggered by UV and visible light.
• Demonstrated wavelength-dependent cleavage and reformation of seleno-sulfide and disulfide bonds.
• Observed significant recovery (85-95%) of initial gel stiffness over multiple cycles.
• Correlation between disulfide-diselenide exchange and reduction in G'.

Conclusions:

• Wavelength-controlled disulfide-diselenide chemistry enables the development of light-responsive reversible organogels.
• The reversible nature and tunable stiffness show promise for applications in polymeric actuators and soft robotics.
• This study highlights a novel approach for designing dynamic soft materials with precise external control.