Multifunctional Vitrimer-Like Polydimethylsiloxane (PDMS): Recyclable, Self-Healable, and Water-Driven Malleable Covalent Networks Based on Dynamic Imine Bond

TLDR

Vitrimers are a class of permanently cross‑linked polymers that can be reprocessed into any shape. The study aims to design and synthesize a catalyst‑free PDMS network with dynamic imine bonds. The network is formed by condensation of poly(dimethylsiloxane)etherimide (PDMS‑NH₂), terephthalaldehyde (TA), and tri(2‑aminoethyl)amine (TREA) via amino‑aldehyde reactions. The resulting PDMS network behaves as a vitrimer‑like material, showing rapid stress relaxation (≈64 s at 130 °C), self‑healing and malleability with retained mechanical strength after repeated deformation, and can be reshaped or recycled at room temperature in water through imine exchange, offering a green processing route.

Abstract

Vitrimer is a new class of polymeric materials which can be reprocessed to any shape while being permanently cross-linked. We designed and synthesized a catalyst-free network with poly(dimethylsiloxane)etherimide (PDMS-NH2), terephthalaldehyde (TA), and tri(2-aminoethyl)amine (TREA) through the condensation reaction between amino groups and aldehyde groups. As a result of the exchange reaction of the dynamic imine bond obtained, this PDMS network exhibits the nature of vitrimer-like material, which is examined by solubility and stress-relaxation experiments, and the relaxation time is as short as 64 s at 130 °C. In addition, the vitrimer-like PDMS is malleable and capable of self-healing, and the mechanical properties can be maintained even after three consecutive breaking/mold pressing cycles. Especially, besides heating, this vitrimer-like PDMS can also be recycled and reshaped at ambient temperature due to the exchange reaction of dynamic imine bond when immersed in water, which will potentially lead to green processing of the elastomers.