Molecular Weight Control in Frontal Ring-Opening Metathesis Polymerization

Area of Science:

• Polymer Chemistry
• Materials Science

Background:

• Bulk frontal ring-opening metathesis polymerization (FROMP) traditionally faces challenges in controlling polymer properties.
• Solvents, deoxygenation, and purification steps are often required, limiting scalability and efficiency.

Purpose of the Study:

• To develop solvent-free FROMP methods for enhanced control over polymer molecular weight and dispersity.
• To explore nonlinear propagation modes and create gradient materials using controlled FROMP.

Main Methods:

• Tuning inhibitor loadings and incorporating inhibitory comonomers in FROMP.
• Utilizing norbornene-type monomers for polymerization.
• Investigating thermal transport, reaction kinetics, and gravitational effects on reaction fronts.

Main Results:

• Achieved precise control over molecular weight (39-700 kg mol⁻¹) and low dispersity (as low as 1.07) without solvents or purification.
• Demonstrated the first closed-mold, nonlinear propagation modes (spin modes) in FROMP.
• Successfully constructed materials with gradient compositions and spatially defined variations.

Conclusions:

• Controlled FROMP offers a powerful, scalable, and self-regulating approach for advanced material design.
• This work merges controlled polymerization techniques with self-propagating material manufacturing.
• The findings pave the way for rapid synthesis of complex polymeric materials with tailored properties.