Variation of radiation-induced effects in poly(epichlorohydrin-co-ethylene oxide-co-allyl glycidyl ether) (GECO) terpolymers as a function of molecular and structural architecture

Abstract

The aim of this study was to investigate how radiation-induced effects vary in poly (epichlorohydrin-co-ethylene oxide-co-allyl glycidyl ether) (GECO) terpolymers based on their molecular and structural architecture. To modify the molecular and structural features, we examined GECO terpolymers with different molecular weights and varying ratios of epichlorohydrin (ECH), ethylene oxide (EO), and allyl glycidyl ether (AGE) in their chain structure. Polymers were irradiated at room temperature with accelerated electrons within an absorbed dose range of 0-100 kGy. Before analyzing the effects of ionizing radiation on the terpolymers, a comprehensive characterization of GECO terpolymers was performed using spectroscopic and chromatographic methods. Additionally, previously unknown physicochemical parameters, such as the solubility parameter and Mark-Houwink constants, were identified. The effects of irradiation on the chain structure of the terpolymers were examined using sol-gel, rheological, and spectroscopic methods. It was found that all terpolymers rapidly undergo cross-linking up to a certain dose. Beyond this dose, there is a slight chain scission as the dose increases; however, the gelation percentage up to 100 kGy remains mostly unchanged. It has been observed that the gelation tendency of GECO terpolymers depends on their molecular structure, and the gelation ratio increases with the increase in the AGE content. Using the Charlesby-Pinner and Charlesby-Rosiak equations for each terpolymer, the chain scission and crosslink yield ratio (po/qo), gelation dose (Dg), and virtual gelation dose (Dv) were determined and the effect of ionizing radiation on these terpolymers-whose use has increased in recent years-was analyzed. This study also examined the impact of ionizing radiation on physicochemical parameters such as the Flory constant and solubility parameter, as well as the changes induced in the chemical structure through swelling analyses and spectroscopic analyses, respectively. As a result of the interaction with radiation, the changes observed in the chemical structure particularly in chloride, allyl, and methyl groups were evaluated using FTIR, and a mechanism was proposed for how GECO terpolymers can be cross-linked through radiation