Controlling the sp2/sp3 ratio of amorphous hydrogenated carbon layers (a-C:H) on polylactide acid (PLA) at constant distance but angle-dependent deposition

•sp2/sp3 content in a-C:H is controllable by angular coating.•The roughness increases up to 60° with direct coating.•WVTR of PLA with direct coated a-C:H was reduced by 47%.•The barrier effect is no longer present from a coating angle of 60°.