Is a Vitrimer with a High Glass Transition Temperature Available? A Case Study on Rigid Polyimides Cross-Linked with...

Area of Science:

• Polymer Science and Engineering
• Materials Chemistry

Background:

• Vitrimers are cross-linked polymers with adaptable networks, combining malleability and recyclability.
• Their dynamic behavior depends on glass transition temperature (T_g) and bond-exchange rate (T_v).

Purpose of the Study:

• To investigate the impact of high T_g on the stress relaxation and physical recyclability of vitrimers.
• To use a high T_g polyimide with dynamic ester bonds as a model system.

Main Methods:

• Studied stress relaxation behavior of a polyimide vitrimer at different temperatures relative to its T_g.
• Assessed physical malleability and recyclability under processing conditions.
• Examined potential side reactions during recycling and reprocessing.

Main Results:

• The polyimide vitrimer showed limited stress relaxation at 10 °C above its T_g (310 °C).
• Significant stress relaxation (3300 s) and malleability were achieved at 345 °C.
• Harsh recycling conditions (high temperature/pressure) can lead to side reactions, altering thermal properties.

Conclusions:

• High T_g necessitates higher processing temperatures for vitrimer malleability and recyclability.
• Diffusion control is critical for the topological transition in high T_g vitrimers.
• A T_g ceiling exists, posing a challenge for future vitrimer development.