Hydrogel based on patch halloysite nanotubes: A rheological investigation

Abstract

The rheological behaviour of Patch halloysite nanotubes (PT_Hal) was investigated here. Their peculiar morphology shows longer and thinner nanotubes and gives rise to the formation of gel-like systems that are not evidenced in halloysite from other natural sources. According to frequency sweep tests, PT_Hal possesses solid-like characteristics even at low concentrations, suggesting that the material is highly structured. Interestingly, flow ramp analysis evidenced two distinct behaviours based on the clay concentration: a yield stress was detected only from 0.75 wt%, indicating the sample's ability to resist deformation or breaking. Furthermore, the study investigated the influence of ionic strength, revealing that the addition of salt did not significantly affect the gel's properties of this clay. Accordingly, in this work we propose a new hydrogel system based on green nanoclays that can be suitable for industrial and biological applications as well as for cultural heritage.