Polyacrylate Vitrimer Network via In Situ Isocyanide Copolymerization: Synthesis and Molecular Dynamics

TL;DR

This paper introduces a new sustainable polymer material that can be recycled while maintaining its mechanical properties, offering insights into its dynamic chemical behavior and electrical properties.

Contribution

A novel one-step photocopolymerization method is introduced to create polyacrylate vitrimer networks with dynamic covalent bonds.

Findings

The material maintains mechanical performance after three reprocessing cycles.

Bond-exchange relaxation transitions from kink-like to Arrhenius behavior after annealing.

Bond exchange mechanisms influence charge transport and increase dielectric permittivity.

Abstract

Widespread plastic
pollution highlights the urgent need
for materials
with sustainable end-of-life management. Vitrimers, cross-linked polymers
containing dynamic covalent bonds, combine the durability of thermosets
with their recyclability. Here, we report a one-step photocopolymerization
using multifunctional isocyanides as readily accessible cross-linkers
that directly introduce vinylogous urethane-like linkages into polyacrylate
networks, structures difficult to obtain via amine–β-ketoester
condensation. The resulting materials show good reprocessability,
maintaining a comparable mechanical performance after three processing
cycles. Broadband dielectric spectroscopy (BDS) reveals that the temperature
dependence of the bond-exchange relaxation times evolves from a kink-like
response in fresh samples to Arrhenius behavior after annealing, visualizing
topological rearrangement and defect healing. A scaling relationship
between bond-exchange relaxation and electrical conductivity establishes
that the former is the underlying mechanism for charge transport in
vitrimers. Furthermore, dipolar intermediates generated during bond
exchange increase the dielectric permittivity, providing new insight
into designing sustainable dielectric materials.

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