Highly Self-Healable Polymeric Coating Materials with Enhanced Mechanical Properties Based on the Charge Transfer Complex

Abstract

Polymeric coating materials (PCMs) are promising candidates for developing next-generation flexible displays. However, PCMs are frequently subjected to external stimuli, making them highly susceptible to repeated damage. Therefore, in this study, a highly self-healing PCM based on a charge transfer complex (CTC) was developed, and its thermal, self-healing, and mechanical properties were examined. The self-healing material demonstrated improved thermal stability, fast self-healing kinetics (1 min), and a high self-healing efficiency (98.1%) via CTC-induced multiple interactions between the polymeric chains. In addition, it eliminated the trade-off between the mechanical strength and self-healing capability that is experienced by typical self-healing materials. The developed PCM achieved excellent self-healing and superior bulk (in-plane) and surface (out-of-plane) mechanical strengths compared to those of conventional engineering plastics such as polyether ether ketone (PEEK), polysulfone (PSU), and polyethersulfone (PES). These remarkable properties are attributed to the unique intermolecular structure resulting from strong CTC interactions. A mechanism for the improved self-healing and mechanical properties was also proposed by comparing the CTC-based self-healing PCMs with a non-CTC-based PCM.

Highly Self-Healable Polymeric Coating Materials Based on Charge Transfer Complex Interactions with Outstanding Weatherability

“…The CTC formation in conventional PIs is driven by electrical interactions between electron-rich aromatic diamines (serving as electron donors) and electron-deficient aromatic dianhydrides (acting as electron acceptors). In general, aliphatic and alicyclic diamines with fewer electrons are considered ineffective electron donors because of their electron-deficient nature [44]. However, the results from Figures 1b-e and 3 reveal that aliphatic diamines with abundant electrons can induce effective CTC formation.…”

“…As a result, self-healing materials based on physical interactions emerge as a more suitable approach to protect the surface and internal components of the device. Typical physical interactions used for self-healing materials include ionic interaction [32][33][34], hydrogen interaction [35][36][37], host-guest interaction [38,39], metal-ligand coordination [40][41][42], and charge transfer complex interaction [43,44]. Because of the intrinsic reversibility of these interactions, self-healing materials based on physical interactions have the potential to efficiently and repeatedly repair damage at specific sites.…”

Properties and Applications of Self-Healing Polymeric Materials: A Review

“…Theoretically, intrinsic self-healing materials offer the crucial advantage of performing unlimited self-healing cycles. However, intrinsic self-healing materials pose a significant challenge: the trade-off between mechanical strength and self-healing performance [12,54,[61][62][63][64]. This trade-off arises from fundamental differences in the underlying concept of polymeric motion.…”