Acetylene coating on cornstarch plastics produced by cold plasma technology

This study tested the effectiveness of sulfur hexafluoride (SF 6 ) plasma treatment and acetylene (C 2 H 2 ) plasma polymerization for turning thermoplastic starch (TPS) hydrophobic. A surface modification method was employed using different precursor gases, SF 6 and C 2 H 2 , and a combined treatment using SF 6 followed by C 2 H 2 (SF 6 /C 2 H 2 ) and then the reverse, using C 2 H 2 first followed by SF 6 (C 2 H 2 /SF 6 ). The same self‐bias voltage and treatment time was used for each gas across all treatments: −100 V and 480 s for SF 6 , −200 V and 2400 s for C 2 H 2 . The best results were obtained from a C 2 H 2 ‐coated surface, treated with SF 6 (C 2 H 2 /SF 6 ). This process increased the contact angle to >128°. When treated in the opposite order (SF 6 /C 2 H 2 ), the contact angle decreased to 90° and a homogeneous, smoother coating was produced. Raman spectroscopy confirmed the presence of D and G bands in plasma‐treated films. Under these treatments, all surfaces presented a contact angle higher than 75°.