Integrated Hydrophilic Interdigitated Network for Silicone Rubber via a Gradient Polarity Modification Strategy

Enabled by excellent biocompatibility and functional designability, hydrophilic flexible functional materials are gaining traction in fields like flexible electronics and implantable/interventional medical devices. Silicone rubber (SR), as a conventional high-performance material, exhibits outstanding flexibility, fatigue resistance, and biocompatibility, making it an ideal substrate for constructing such functional materials. However, its inherent hydrophobicity and low surface energy severely limit compatibility with polar modifiers and hinder further functionalization. To address this, we developed a universal in situ modification strategy based on a "gradient polarity modification" concept. By establishing a polarity transition ladder between SR and strongly polar hydrophilic materials (e.g., quaternary ammonium and zwitterionic compounds), this method successfully achieves a hydrophilic interdigitated SR network and enables modification from the surface to the bulk. The resulting materials exhibit a combination of superior properties, including persistent bulk hydrophilicity, remarkable aqueous lubrication, and maintained mechanical robustness. By demonstrating the successful fabrication of a lubricative/antibacterial catheter and a long-lasting lubrication meniscus, this strategy proves to be highly designable in function and directly applicable for modifying pre-formed SR devices. Its exceptional responsiveness, as confirmed by motion capture, underscores a significant potential for use in advanced sensing applications.