Hexadecylamine Addition Promotes Crystallization-Driven Functionalities in Freezing-Thaw PVA Hydrogels

Poly-(vinyl alcohol) (PVA) is widely employed for hydrogel fabrication due to its ability to form stable, physically or chemically cross-linked three-dimensional networks. Among production methods, the freezing-thaw (F-T) technique stands out for its simplicity and effectiveness. This study presents a straightforward methodology for preparing functional PVA hydrogels in aqueous media by blending PVA with a crystallizable hexadecyl alkylamine (C16). Incorporating small amounts of hydrophobic, amphiphilic hexadecylamine into PVA hydrogels via freezing-thaw blending significantly alters crystallization and network structure, enabling gel formation in water without surfactants, solvents, or cross-linkers. C16 enhances phase separation and promotes PVA crystalline domains while remaining amorphous. The resulting PVA/C16 hydrogels exhibit enhanced thermomechanical properties, demonstrating additional functionalities such as self-healing and improved adhesion to polar surfaces. This crystallization-driven gelation via immiscible blending offers a scalable strategy with potential in wearable electronics, soft robotics, and biomedical devices.