Radiation-Induced Synthesis of Polymer Networks Based on Thermoresponsive Ethylene Glycol Propylene Glycol Monomers

In this paper, different poly((ethylene glycol)-(propylene glycol)) methacrylate (P(EGPG)MA) hydrogels were synthesized by gamma-radiation-induced polymerization and crosslinking from a monomer-bisolvent mixture using the following monomers: (ethylene glycol)₆ methacrylate (EG₆MA), ((ethylene glycol)₆-(propylene glycol)₃) methacrylate (EG₆PG₃MA), ((propylene glycol)₆-(ethylene glycol)₃) methacrylate (PG₆EG₃MA), and (propylene glycol)₅ methacrylate (PG₅MA), along with different water/ethanol compositions as the solvent. The monomer-bisolvent mixture was exposed to various radiation doses (5, 10, 15, 25, and 50 kGy). Considerable emphasis was placed on optimizing and tuning the reaction conditions necessary for the fabrication of methacrylic networks with pendant EGPG terminals. A further investigation was conducted on the effects of monomer composition, different preparation conditions, and radiation processing on thermal properties, microstructure, swelling behavior, and volume phase transition. Special attention was dedicated to PPG₆EG₃MA hydrogel, whose volume phase transition temperature is near physiological temperatures. This study identifies an optimal radiation dose and a water/ethanol solvent ratio for the synthesis of the radiation-induced hydrogels. Employing ionizing radiation within the sterilization dose range enables the simultaneous fabrication and sterilization of these hydrogels, offering an efficient production process. The findings provide new insights into the role of bisolvent composition on hydrogel formation and properties, and they present practical guidelines for optimizing hydrogel synthesis across a wide range of applications.