Biphasic mechanochemistry of single-chain polymerization

Area of Science:

• Polymer Chemistry
• Single-Molecule Biophysics
• Mechanochemistry

Background:

• Mechanical forces are known to influence chemical reactions, including reaction kinetics and signal production.
• Understanding how forces affect polymerization is crucial for controlling polymer properties.

Purpose of the Study:

• To investigate the effects of mechanical force on the kinetics of single-chain ring-opening metathesis polymerization (ROMP).
• To elucidate the mechanisms behind force-dependent polymerization kinetics at the single-molecule level.

Main Methods:

• Utilized magnetic tweezers-based single-molecule force spectroscopy to apply controlled forces.
• Analyzed real-time single-chain growth trajectories during ROMP.

Main Results:

• Observed a biphasic force dependence of polymerization rate: initially decreasing, then increasing with force.
• Identified distinct polymerization regimes with and without entanglement formation, both exhibiting biphasic behavior.
• Proposed mechanisms involving force-induced entanglement dynamics and catalyst structural changes.

Conclusions:

• Mechanical force can be used to precisely control polymerization kinetics and potentially tune polymer properties.
• The study reveals complex mechanochemical pathways in single-polymer chain synthesis.
• Findings open avenues for force-mediated polymer synthesis and material design.