Conversion of Ultrathin Polymer Film to Graphene

Abstract

The significant progress in the growth of large-area uniform graphene films using a chemical vapor deposition method has been made over the last few years, but still some challenges remain for practical applications. In this study, we demonstrate some approaches to overcome the challenges by using polymer as a carbon source. We aim for investigating the conversion mechanism of special polymer sources to graphene and finally growing high quality graphene at low temperature. First, we show the conversion of thermally-resistant polyimide (PI) as a carbon precursor to graphene, which is different from the graphene growth using previous solid carbon sources like poly(methyl methacrylate). The ultrathin Langmuir–Blodgett films of poly(amic acid) (~0.7 nm) were coated on copper foils and then converted to graphene via a PI intermediate. The Cu foil substrate facilitates the reorientation of aromatic moieties during the carbonization process of PI. Graphene grown by this method featured a relatively large domain size and an absence of adventitious adlayers. Next, newly designed poly(vinyl butadiyne) (PVbd) was used as a carbon precursor to lower the graphene growth temperature. We show a possibility of converting PVbd to graphene at 600 oC through the cyclization reaction followed by rearrangement of aromatic moieties. We discuss that an oxidation process of PVbd and a cooling rate after the growth are important for the graphene growth.