Diamond-like carbon coating of a pure bioplastic foil

• Published in: Thin solid films 2013-10, Vol.545, p.558-563
• Main Authors: Rohrbeck, Magdalena, Körsten, Susanne, Fischer, Christian B., Wehner, Stefan, Kessler, Barbara
• Format: Article
• Language: English
• Subjects: Biodegradable; Bioplastic; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Coating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Deposition; Diamond-like carbon (DLC); Diamond-like carbon films; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Exact sciences and technology; Exfoliation; Flakes; Foils; Fullerenes and related materials; diamonds, graphite; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Plasma enhanced chemical vapor deposition (PECVD); Plastics; Polyhydroxybutyrate (PHB); Scanning electron microscopy (SEM); Specific materials; Structure and morphology; thickness; Surface and interface electron states; Surface states, band structure, electron density of states; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2013.07.028

Bioplastic materials are a promising replacement for petroleum-based plastics. Coating is an often used method to improve characteristics of traditional plastic materials. We present results of the coating of a 50μm thick pure bioplastic foil, a mixture of 92% polyhydroxybutyrate and 8% polyhydroxyvalerate, with diamond-like carbon (DLC) via a radio frequency plasma enhanced chemical vapor deposition process. Two different types of DLC are deposited on the foil, an sp3-rich (r-DLC) and an sp2-rich (f-DLC). The first type results in a more robust the second in a more flexible kind of coating. The surface morphologies of layers with various thicknesses are examined, r-DLC up to 1000nm, f-DLC up to 200nm. DLC layers up to around 450nm are intact, further deposition results in cracking and exfoliation of the DLC coating. The exfoliated DLC flakes roll up during the ongoing plasma process. This process is observed again on the thereby newly exposed substrate between the flakes. Rolling of the DLC flakes shows the presence of internal stress in the deposited DLC coating. •Coating of a pure bioplastic foil with diamond-like carbon (DLC) can be performed•Coating with flexible as well as robust DLC is possible•DLC layers are entirely closed up to around 450nm thickness