Fogging on optical devices may severely impair vision, resulting in unacceptable adverse consequences. Hydrophilic coatings can prevent surface fogging by instantly facilitating pseudo-film water condensation but suffer from short antifogging duration due to water film thickening with further condensation. Here, an innovative strategy is reported to achieve longer antifogging duration via thickening the robust bonded hydrophilic/hydrophobic polymer heteronetwork coating to enhance its water absorption capacity. The combination of strong interfacial adhesion and hydrophilic/hydrophobic heteronetwork structure is key to this approach, which avoids interfacial failure and swelling-induced wrinkles under typical fogging conditions. The developed antifogging coating exhibits prolonged antifogging durations over a wide temperature range for repetitious usages. Eyeglasses coated with this coating successfully maintained fog-free vision in two typical scenarios. Besides, the coating recipes developed in this study also have potential as underwater glues as they demonstrate strong adhesions to both glass and polymer substrates in wet conditions.
Understanding the conformational dynamics of polymer chains interacting with colloidal particles is of great significance to manipulate the properties of nanocomposites and polymer−solid interfaces. Herein, the complexation between high molecular weight poly(ethylene oxide) (PEO) and silica nanoparticles (SPs) in dilute solution was investigated with viscometry, electron microscopy, and scattering techniques. In the presence of SPs, PEOs rapidly collapsed from an extended coil to a compact conformation onto the surface of silica, which simultaneously caused a decrease in solution viscosity. A viscosity minimum together with a compact complex structure was achieved. Further addition of SPs induced polymer chains to extend into the coil state, leading to a substantial viscosity increase and structural expansion of the complex. This phenomenon was rationalized by the delicate balance between noncovalent forces including hydrogen bonding between polymer and SPs, as well as electrostatic repulsion between SPs. A series of physiochemical conditions such as pH, ionic strength, polymer molecular weight, and particle size were systematically explored to unravel the factors governing polymer conformation changes. We envision that this research will shed light on the fundamental understanding of polymer−colloid nanocomposites at the nanoscale level and provide guidelines for the design of functional composite materials.
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