Catalytic Control of Crystallization in Dynamic Networks

Area of Science:

• Polymer Chemistry
• Materials Science
• Chemical Engineering

Background:

• Semicrystalline polymer networks rely on dynamic covalent bonds for self-healing and recyclability.
• Understanding the interplay between bond exchange dynamics and crystallization is crucial for designing advanced polymer materials.

Purpose of the Study:

• To investigate how catalyst nucleophilicity influences thiol-thioester bond exchange dynamics.
• To determine the effect of varying bond exchange rates on the crystallization behavior of polymer networks.

Main Methods:

• Utilized a model semicrystalline polymer network with catalysts of varying nucleophilic strength.
• Employed differential scanning calorimetry (DSC) for isothermal crystallization measurements.
• Performed Lauritzen-Hoffman analysis to study nucleation barriers.

Main Results:

• Catalyst nucleophilicity tuned covalent bond exchange time scales (τ) over 10^1–10^3 s.
• Increased bond exchange rates led to decreased melting temperatures and slowed crystallization kinetics.
• A significant increase in the secondary nucleation barrier was observed in dynamic networks.

Conclusions:

• Catalyst-controlled bond exchange dynamics directly influence polymer crystallization.
• While faster bond exchange initially hinders crystallization, it facilitates long-term crystal rearrangement and growth.
• These findings offer insights into designing dynamic polymer networks with tunable properties.