Tuning the Mechanical, Electrical, and Optical Properties of Flexible and Free-Standing Functionalized Graphene Oxide Papers Having Different Interlayer d Spacing

Functionalized graphene oxide papers are assembled materials with a wide range of potential applications; however, scientific studies about how the physical properties of functionalized graphene oxide papers are affected by the presence of new functional groups have not been addressed. Here, electrical resistance, optical band gap, and mechanical properties of flexible and free-standing functionalized graphene oxide papers with nitroxide moieties (NGOP’s) have been studied, and two of them (mechanicals and electricals) were correlated with the interlayer d spacing for the first time; herein, a new insight about the key role that an optimum amount of functionalization agent plays over the physical properties of NGOP’s is presented. In all cases, (functionalized or pristine) graphene oxide papers were prepared using anhydrous DMF instead water in order to study and highlight the pure effect of the functionalized groups over their physical properties. The functionalized nanomaterials exhibited significantly improved physical properties, which can be tuned by varying the interlayer d spacing, and this interlayer distance was systematically modified controlling the amount of functionalizing agent used. Thus, controlling the amount of functionalizing agent in the functionalization process is possible to obtain new assembled materials with modulated properties.