Dynamic imine-mediated pH-responsive polymer-mesoporous silica interfaces regulating molecular transport

The regulation of molecular transport in stimuli-responsive interfacial materials is critical for colloid science, yet controlling active-agent release in soft polymer-nanomaterial systems remains a challenge. We hypothesize that constructing a reversible polymer-nanoparticle network through dynamic covalent chemistry can enable precise, pH-triggered molecular transport. Specifically, interconnecting vanillin-modified polyvinyl alcohol (PVA) with amino-functionalized mesoporous silica via acid-labile imine linkages should create an interfacial system where local pH variations directly control bond cleavage, agent release, and material properties. Nanoscale confinement and aromatic-group-related interfacial interactions are expected to influence wettability and transport behavior.

A pH-responsive hybrid composite film was fabricated by reacting vanillin-modified PVA with amino-functionalized mesoporous silica to form dynamic imine linkages. The formation of the reversible interfacial network was confirmed using spectroscopic analyses, including Fourier-transform infrared and X-ray photoelectron spectroscopy (XPS). The pH-triggered release behavior and interfacial dissociation were investigated through controlled release studies. The pH-dependent interfacial dissociation was evaluated using time-dependent ATR-FTIR and high-resolution XPS, while vanillin transport was quantified through controlled release experiments and kinetic modeling. The functional performance was evaluated by measuring antibacterial activity against Escherichia coli and Staphylococcus aureus, alongside assessments of hydrophobicity and water vapor permeability.

The dynamic imine interfaces successfully conferred pH-responsive behavior, with acid-triggered bond cleavage enabling controlled molecular release. Decreasing pH increased both the apparent CN cleavage ratio and the vanillin release rate, establishing a direct relationship between dynamic interfacial dissociation and molecular transport. This interfacial dissociation directly correlated with effective membrane disruption in bacteria, demonstrating potent antibacterial activity. Furthermore, the incorporation of aromatic ASBAVA altered the interfacial wettability and produced composition-dependent gas and water-vapor transport behavior. This work establishes that dynamic covalent interfaces are a powerful strategy for regulating stimulus-responsive transport and structure-property relationships in soft colloidal systems.