Functional Hyper-Crosslinkers.

Crosslinking is an essential architecture for polymers to improve mechanical and thermal properties and to form three-dimensional (3D) structures. Although conventional synthetic crosslinkers usually only serve as bridges between different polymeric chains, biological crosslinkers are multifunctional. Recently, crosslinkers with active functionality after polymerization are promising a new dimension of molecular design for generating smart materials as they may exhibit dramatic changes in structures and properties in response to external stimuli. This concept article introduces several different designs of hyper-crosslinkers (i.e., multifunctional crosslinkers that provide three or more sites for generating networks) and their applications in tailoring stimuli-responsive and self-healing soft materials. Particularly, the polymeric materials that contain functional hyper-crosslinkers are exhibiting anti-intuitive redox or thermal-pH responses. The goal of this article is to illustrate the concept that functional hyper-crosslinkers not only improve the physical and chemical performance of the polymers, but more importantly, may introduce new architectures and functionalities for soft materials.