Issue 38, 2023

Solvent-free preparation of imine vitrimers: leveraging benzoxazine crosslinking for melt processability and tunable mechanical performance

Abstract

Covalent adaptable networks, particularly imine vitrimers, have received considerable attention for the design of recyclable and reprocessable thermoset-like materials. However, the preparation of imine vitrimers often relies on solvent casting approaches that lack compatibility with existing polymer processing techniques and limit their practical application as thermoset replacements. Therefore, alternative vitrimer precursors with inherent melt processability are necessitated to realize the full potential of these recyclable materials. In this work, dynamic imine vitrimers were prepared in a solvent-free approach by employing orthogonal benzoxazine polymerizations. A series of imine-containing benzoxazine monomers were prepared to yield vitrimer precursors with tailorable rheological profiles and melt-state processability. Upon further heating, the benzoxazine functionalities undergo a condensate-free homopolymerization to yield networks with varied glass transition temperatures (34–160 °C) and impressive tensile strengths (up to 80 MPa). The incorporation of imine bonds into the backbone of the benzoxazine networks imparts efficient stress relaxations through metathesis exchange reactions, enabling malleability and repeated reprocessability at elevated temperatures. Dynamic exchange kinetics are found to be strongly correlated with crosslink density, with activation energies ranging from 70–177 kJ mol−1. Additionally, we demonstrate that exposure to acidic conditions results in hydrolysis of the dynamic imine linkages, leading to full dissolution of the benzoxazine networks. This work demonstrates a solvent-free approach for preparing imine vitrimers by employing an orthogonal polymerization, and provides insight for the molecular design of processable recyclable thermosets.

Graphical abstract: Solvent-free preparation of imine vitrimers: leveraging benzoxazine crosslinking for melt processability and tunable mechanical performance

Supplementary files

Article information

Article type
Paper
Submitted
23 Jūl. 2023
Accepted
08 Sept. 2023
First published
14 Sept. 2023

J. Mater. Chem. A, 2023,11, 20568-20582

Author version available

Solvent-free preparation of imine vitrimers: leveraging benzoxazine crosslinking for melt processability and tunable mechanical performance

L. J. Hamernik, W. Guzman and J. S. Wiggins, J. Mater. Chem. A, 2023, 11, 20568 DOI: 10.1039/D3TA04351G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements