Protective films on complex substrates of thermoplastic and cellular elastomers: Prospective applications to rubber, nylon and cork

Deposition of thin films is an appropriate methodology to enhance the performance of a material by modification of its surface, while keeping the properties of the bulk largely unaffected. However, a practical implementation becomes less straightforward when dealing with sensitive or complex substrates, for instance, those which cannot be subjected to harsh treatments, such as cleaning and etching, or extreme deposition conditions, like high temperatures, and ion impingement et cetera. This paper concentrates on deposition processing of complex substrates. In particular, it discusses the deposition of two types of protective coatings (diamond-like carbon (DLC) films against friction and wear, and TiO₂ films against UV light) on three types of thermoplastic and cellular elastomers (rubber, nylon and cork). It is demonstrated that a successful protection of thermoplastic elastomers against wear with DLC films can be attained, after a thorough adaptation of the procedure to the characteristics of the specific substrate. In addition, the paper reports the very first depositions on a cellular elastomer like cork by vapor deposition methods, including Atomic Layer Deposition (ALD).