Photoresponsive gels prepared by ring-opening metathesis polymerization

Area of Science:

• Polymer Chemistry
• Materials Science
• Photochemistry

Background:

• Photoresponsive polymers offer tunable properties through light stimuli.
• Ring-opening metathesis polymerization (ROMP) is a versatile method for polymer synthesis.
• Developing materials that dissolve on demand is crucial for advanced applications.

Purpose of the Study:

• To synthesize novel photoresponsive gels using ROMP.
• To investigate the light-induced dissolution mechanism of these gels.
• To explore the influence of cross-linker structure and density on gel properties.

Main Methods:

• Synthesis of cross-linked polymer networks via ROMP using norbornene monomers and new photoreactive cross-linkers.
• Incorporation of o-nitrobenzyl ester (NBE) moieties within the cross-linker structure.
• Irradiation with ultraviolet (UV) light to induce photolysis of NBE groups and gel dissolution.
• Characterization of gel swelling behavior in organic solvents and water.

Main Results:

• Cross-linked polymer gels were successfully prepared using ROMP.
• The gels exhibited swelling in various solvents, with behavior dependent on monomer structure.
• UV irradiation led to the homogenization of the gels, indicating cross-linker cleavage.
• Dissolution time correlated with cross-link density and the specific structure of the photoresponsive cross-linker.

Conclusions:

• Novel photoresponsive gels dissolvable by UV light were synthesized using ROMP.
• The o-nitrobenzyl ester (NBE) groups in the cross-linkers facilitate light-induced network cleavage.
• These materials demonstrate potential for applications requiring controlled degradation or dissolution.