Real time quantification of the chemical cross-link density of a hydrogel by in situ UV-vis spectroscopy

Abstract

In this paper, we prepare a hydrogel in a green method via the redox reaction between phenol groups and Eosin Y by visible light irradiation. Eosin Y shows significant absorption at 515 nm while the reduced product does not. A series of control experiments show that almost 100% of the consumed Eosin Y reacted with phenol groups to form cross-link points. On the basis of the two results, the chemical cross-link density can be easily determined quantitatively by UV-vis spectroscopy. With this method, specimens from the state of the starting solution to solid gel can be measured in situ and in real time without any pretreatment. The result obtained by this new method is proved by traditional rheological measurements.