Graphene oxide as a stabilizing additive: effect of the oxidation degree on wettability, thermal stability, and dispersion
Keywords:
graphene oxide, oxidation degree, surface free energy, wettability.Abstract
This work evaluated the influence of the oxidation degree of graphene oxide on its structural, thermal, and interfacial properties in order to assess its performance as a stabilizing additive in dispersed systems. Graphene oxide was synthesized by a modified Hummers method, varying the reaction time to obtain samples with different oxidation degrees.
FTIR spectroscopy and X-ray diffraction confirmed the incorporation of oxygen-containing functional groups and structural changes associated with oxidation, without showing a strictly proportional relationship between reaction time and oxidation degree. Thermogravimetric analysis revealed differences in thermal stability among the samples, related to the content and nature of oxygen functional groups. Contact angle and surface free energy measurements indicated that oxidation degree affects water affinity and amphiphilic character, although no linear trend with reaction time was observed.
Dispersion tests in liquid–liquid systems showed that the interfacial behavior of graphene oxide depends on both oxidation degree and medium pH. In particular, the sample obtained after 3 h of oxidation (GO 3H) exhibited the most favorable behavior, with greater sensitivity to pH changes and better redistribution between phases. These results indicate that controlling the oxidation degree is a key parameter for tuning the interfacial properties of graphene oxide for potential use as a stabilizing material.
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