The Influence of Polyamide-6 on the Structure and Functional Properties of Composite Hydrogels Based on Polyvinylpyrrolidone Copolymers

Controlling the balance between mechanical characteristics and sorption–diffusion properties remains one of the main challenges in the development of hydrogel materials. In this work, a method for obtaining composite copolymers of polyvinylpyrrolidone (PVP) with 2-hydroxyethyl methacrylate (HEMA) by modifying them with polyamide-6 (PA-6) during polymerization is proposed. PA-6/pHEMA-gr-PVP composite copolymers and hydrogels based on them were synthesized by polymerization of 2-hydroxyethyl methacrylate in the presence of a combined polymer matrix containing unbound PVP and a preformed PVP/PA-6 interpolymer complex (IPC). The existence of the IPC and its effect on the hydrogel structure were investigated using viscosity measurements, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The results of the study show that PA-6 and PVP form a hydrogen-bonded IPC, which modifies the supramolecular organization of the hydrogel structure. This structural rearrangement increases the density of physical crosslinking within the polymer network, leading to improved mechanical strength and elasticity while reducing the water content, swelling rate, and osmotic permeability of the hydrogels. The obtained results demonstrate an effective approach to designing the structure of hydrogels and allow a simultaneous adjustment of their mechanical, sorption, and diffusion properties. This opens new possibilities for the development of mechanically strong hydrogel membranes with adjustable permeability for membrane and biomedical applications.