Mechanical Stretch α-Cyclodextrin Pseudopolyrotaxane Elastomer with Reversible Phosphorescence Behavior

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Polymer Chemistry

Background:

• Supramolecular chemistry offers novel routes to engineer material properties.
• Cyclodextrin inclusion complexes are key components in advanced functional materials.
• Waterborne polyurethanes (WPUs) are versatile elastomers with growing applications.

Purpose of the Study:

• To develop novel supramolecular elastomers with enhanced mechanical and luminescent properties.
• To investigate the mechanism of room-temperature phosphorescence (RTP) induction and modulation.
• To explore the potential of mechanically responsive luminescence in smart materials.

Main Methods:

• Synthesis of naphthalene-functionalized pseudopolyrotaxane (NPR) via threading polyethylene glycol chains into α-cyclodextrin.
• Incorporation of NPR into waterborne polyurethane (WPU) matrices through hydrogen bonding.
• Characterization of mechanical properties, thermal stability, and room-temperature phosphorescence (RTP) under various conditions and mechanical strains.

Main Results:

• NPR successfully induced RTP in naphthalene moieties through cyclodextrin confinement.
• The resulting WPU elastomers exhibited enhanced mechanical strength and stable RTP emission across diverse environments (water, acid, alkali, organic solvents, 160 °C).
• A significant, reversible increase in phosphorescence intensity (up to threefold under 200% strain) was observed upon mechanical stretching, attributed to inhibited non-radiative transitions.

Conclusions:

• Supramolecular elastomers incorporating NPR demonstrate robust RTP and tunable luminescence.
• Mechanical stimuli can reversibly modulate the phosphorescence behavior, opening avenues for strain-sensing materials.
• This work presents a new strategy for designing advanced supramolecular luminescent materials with mechanical responsiveness.