Swelling-induced Mechanochromism in Multinetwork Polymers.

Area of Science:

• Polymer Chemistry
• Materials Science
• Mechanochemistry

Background:

• Polymer networks often undergo degradation or irreversible changes upon swelling.
• Controlling mechanochemical reactions within polymer networks remains a challenge.

Purpose of the Study:

• To develop a novel multinetwork (MN) strategy for swelling-induced mechanochemistry.
• To enable repeated swelling and controlled mechanochemical reactions in polymer networks.
• To demonstrate tunable reactivity through hierarchical network design.

Main Methods:

• Utilized a multinetwork (MN) strategy with a first network (FN) and a radical-based mechanophore, difluorenylsuccinonitrile (DFSN).
• Investigated isotropic expansion of the FN to induce mechanochemical scission of DFSN.
• Analyzed kinetic stabilization of radicals and enhanced thermal reactivity within the swollen gels.

Main Results:

• Achieved swelling-induced mechanochemistry through isotropic expansion of the FN.
• Observed kinetic stabilization of pink radicals in the swollen polymer gels.
• Demonstrated increased thermal reactivity of DFSN due to entropic contributions from the FN.
• Showcased MN polymers for network modification and tunable reactivity.

Conclusions:

• The MN strategy provides a versatile approach to swelling-induced mechanochemistry.
• Hierarchical network architecture allows for tunable reactivity of dissociative units.
• This method offers potential for developing advanced responsive polymer materials.