Nanoparticle-Enabled Interfacial Kinetic Control of Bond-Exchange Reactions: Insights from Biomedical Poly(ε-caprolactone)-Based Dynamic Polymers.

Poly(ε-caprolactone) (PCL)-based dynamic polymers are promising adaptive biomaterials due to their biocompatibility, biodegradability, and high chain mobility; however, the onset temperature for bond-exchange reactions, often referred to as topology-freezing temperature, Tv, remains difficult to control and is typically treated as a bulk property governed by catalyst selection and network structure. Consequently, many reported dynamic polymers operate at temperatures well above the biomedical operating window, limiting their biomedical applicability. Here, we propose an interfacial kinetic engineering strategy in which nanoparticle-polymer interfaces act as localized kinetic regulators of dynamic covalent bond exchange. By tailoring nanoparticle (NP) surface chemistry, including functional group density, polarity, and catalytic activity, the activation energy (Ea) can be modulated at the nanoscale, enabling programmable control of Tv. Exchange kinetics in PCL-based dynamic polymers are expected to be highly sensitive to the local chemical environment, indicating that interfacial effects can decouple dynamic behavior from bulk composition. This perspective establishes NP-dynamic polymer interfaces as a programmable kinetic design parameter for controlling bond-exchange reactions in dynamic polymer networks, opening a pathway toward spatially defined covalent adaptable materials with application-specific and programmable dynamic behavior.