The films were annealed at ~150°C, and their structure was dramatically affected. The exothermic transformation at 197°C (up to 111 J/g for G 0 (6), by DSC), which is associated to a defined mass loss at the same temperature (up to 3wt% loss for G 0 (6), by TGA), is the result of condensation reactions among the functional groups. Most of the functionalities are hydroxyl groups (see Figure ), but also some carboxyl groups can be added during synthesis or heating , which can react forming ether, ester and anhydride bridges among the sheets. The mass loss observed by TGA can be directly associated to the evaporation of the water, and less frequently other molecules such as ethyl alcohol, produced by the different possible mechanisms of these reactions . These reactions allow further structuration and the crosslinking of the films, allowing their reinforcement at a much milder temperature than graphitization processes and avoiding temperature-related limitations to their applications. After crosslinking the Geh species are very thermal resistant even in oxidative atmospheres, with thermooxidative decomposition temperatures above 600°C (Figure ).