Elemental and Stable Isotope Validation of Stepwise Graphene Oxide Functionalization to GRAPHYMERE^®

Stepwise functionalization of graphene oxide (GO) into polymerizable derivatives requires analytical evidence able to distinguish chemical modification from the spectral overlap typical of oxidized carbon frameworks. Here, pristine GO, amine-functionalized GO (GO-ED), and the methacrylamide-modified derivative GRAPHYMERE^® were compared by elemental analysis and stable isotope ratio mass spectrometry. Carbon content increased progressively from GO to GRAPHYMERE^®, while nitrogen was reproducibly incorporated after amination and retained after methacrylamide modification. The materials also showed a monotonic δ¹³C shift and distinct δ¹⁵N signatures for the nitrogen-containing derivatives, consistent with progressive bulk chemical modification. These elemental-isotopic trends provide complementary support for the proposed functionalization pathway and for the analytical distinction among the starting material, intermediate, and final derivative. EA-IRMS is therefore proposed as an additional batch-screening tool for chemically complex GO-based precursors intended for future polymeric and dental-material applications, without replacing bond-specific structural techniques.