Epitaxial Crystallization of PE Atop Graphene by Vapor Deposition

Epitaxial crystallization of polymers is a fascinating phenomenon that drives crystal structures under lattice matching conditions as a result of the interfacial interactions between specific pairs of a polymer and an underlayer material. However, fundamental investigations of epitaxial crystallization are impeded by the difficulties in preparing uniform ultrathin polymer layers and fine tuning of the film thickness, especially for polymers with low solvent solubility or fast crystallization kinetics such as polyethylene (PE). In this study, exploiting a physical vapor deposition technique, an additive bottom-up approach that is attracting more interest in processing polymers, we demonstrate the ability to achieve better film quality and control of layer thicknesses. By applying the flexible control of substrate temperature and deposition time to the model system of PE epitaxial growth atop graphene substrates, we determine how temperature and film thickness influence crystal structure and lamellar orientation. Characterization include grazing incidence x-ray diffraction (GIXD),TEM and AFM.