Understanding, mimicking and mitigating radiolytic damage to polymers in liquid phase transmission electron microscopy

Advances in liquid phase transmission electron microscopy (LP-TEM) have enabled the monitoring of polymer dynamics in solution at the nanoscale, but radiolytic damage during LP-TEM imaging challenges its routine use in polymer science. Here, we focus on understanding, mimicking and mitigating radiolytic damage observed in functional polymers in LP-TEM. Using polymer vesicles in aqueous solutions as a model system, we quantitatively show how polymer damage occurs in all conceivable (LP-)TEM environments to which polymers might be exposed. It is found that radiolytic damage to polymers is negligible in vacuum but becomes substantial in water-containing environments. We elucidate the primary characteristics of polymer damage in water vapor and liquid water, addressing the observed differences. Furthermore, we introduce ultraviolet light irradiation in the presence of hydrogen peroxide to replicate the observed polymer damage and morphological changes on lab scale, allowing the use of bulk techniques to probe damage at the polymer chain level. Finally, we compare the protective effects of commonly used hydroxyl radical scavengers and reveal that the effectiveness of graphene's protection is distance dependent. We anticipate that our work will help to guide the design of LP-TEM experiments for polymers in a rational and informed manner.