Polymeric Polyaldehyde Approach to Develop Robust Dynamic Covalent Adaptive Polyimine Networks

ABSTRACT Polyimine‐based covalent adaptive networks crosslinked with Schiff bases (PI‐CANs) have been developed as effective building blocks to construct advanced polymeric materials possessing reprocessability, self‐healability, and sustainability. Most approaches to fabricate PI‐CANs involve the synthesis and use of small molecule polyaldehydes. Herein, we report a versatile approach exploring the synthesis of polymeric polyaldehydes (PP‐CHO) with a polyacrylate backbone bearing pendant aldehyde groups to develop self‐healable, reprocessable polyacrylate‐PI hybrid CANs. The approach centers on the synthesis of well‐defined poly(2‐hydroxyethyl acrylate) bearing aldehyde pendants (PHEA‐CHO) by a photo‐indued reversible deactivation radical polymerization,(Photo‐RDRP) followed by post‐polymerization modification. The PHEA‐CHO is highly reactive to an aliphatic diamine, enabling the fabrication of transparent, integrated, dynamic PHEA‐PI hybrid CAN films. They exhibit lower activation energy (E a = 14.6 kcal/mol) for stress relaxation even at mild temperature (50°C – 80°C) and good self‐healability and reprocessability as retaining their mechanical strengths upon a recycle. Promisingly, they degrade to corresponding aldehyde and amine precursors through acid‐catalyzed hydrolysis of benzoic imine crosslinks, offering potential for sustainability as recyclable dynamic covalent systems. These results suggest that the PP‐CHO approach is versatile for the development of dynamic PI‐CAN materials capable of the built‐in ability for extended operation and enhanced reliability.