Composite coating, preparation method and device

A composite coating, comprising a coating I and a coating II;

• wherein, the coating I is a plasma polymeric coating formed by contact of a substrate with plasma containing a monomer α, and the monomer α has a structure represented by formula (1),
• in formula (1), R1 is a vinyl group or a substituted C1-C10 alkyl group, a substituent for the substituted C1-C10 alkyl group comprises at least one selected from a group consisting of halogen atoms, alkenyl groups, alkynyl groups, hydrocarbyloxy groups, amino groups, epoxy groups, acyloxy groups, amide groups, hydroxyl groups and sulfhydryl groups, and R2, R3 and R4 are each independently selected from a group consisting of halogen atoms, C1-C10 alkoxy groups, substituted C1-C10 alkoxy groups, C1-C10 acyloxy groups and substituted C1-C10 acyloxy groups;
• and
• the coating II is a parylene coating formed by vacuum vapor deposition on the coating I.