Force‐Induced Enhancement of Hydrophilicity of Individual Polymethyl Methacrylate Chain†

Comprehensive Summary Polymethyl methacrylate (PMMA) has been widely applied in diverse fields such as medicine and engineering materials due to its good hydrophilicity and biocompatibility. However, another term for PMMA, Plexiglas, means that it is water insoluble. These features of PMMA are valuable but seem paradoxical. To explore the underlying mechanism of the paradoxical properties, the interactions between PMMA and water have been investigated by atomic force microscopy (AFM)‐based single‐molecule force spectroscopy (SMFS). The single‐chain elasticity of PMMA obtained in aqueous solutions is significantly different from that obtained in non‐aqueous environments, implying that PMMA can form hydrogen bonds with water molecules. A proper elongation will promote the hydration of PMMA. These findings reveal the underlying mechanism of interactions between PMMA and water molecules from a single‐molecule perspective, which is helpful for the rational regulation of the mechanical properties of PMMA materials in a bottom‐up way.