Hydrogels based on poly(2-hydroxyethyl methacrylate) and nettle extract

New types of hydrogels based on linear poly(2-hydroxyethyl methacrylate) and poly(ethylene glycol) diacrylate (PHEMA-PEGDA) and nettle extract were obtained. A solution of poly(2-hydroxyethyl methacrylate) in monomer (S-PHEMA) was obtained by bulk photopolymerization. Common nettle extract was used as an ingredient that facilitates wound healing. The influence of the photoinitiator content (1-[4-(2-hydroxymethyl)-phenyl]-2-hydroxy-2-methylpropanone) on the photopolymerization kinetics, as well as the equilibrium swelling ratio (ESR), thermal and mechanical properties of the hydrogels were examined. Complete HEMA conversion was achieved at the lowest photoinitiator dose. Replacing HEMA with S-PHEMA causes an increase in ESR (24%) and Tg (50 degrees C) and the amorphous phase content. At the same time, the tensile strength and Young's modulus decrease. However, the addition of nettle extract (0.3 wt%) requires a significant increase in the amount of photoinitiator (up to 2.5 wt%). As the concentration of the photoinitiator in the system increases, ESR and Tg decrease, but tensile strength and Young's modulus increase.