Study of the mechanical properties of ethyl lactate plasma polymers

Biodegradable and derived from renewable resources, polylactide (PLA) is a potential alternative to conventional synthetic packaging materials. Nevertheless, PLA presents high water permeability leading to its hydrolysis and subsequently limiting its application fields.
In this work, we develop a highly cross-linked PLA-based plasma polymer film synthesized by PECVD that could be used as barrier coating. The permittivity of PLA could be consequently tuned by controlling both the chemistry and the cross-linking degree of the film.[1] In the context of a barrier coating, it is also extremely important to evaluate the mechanical properties of the thin film in order to optimize his interface with the substrate.
Mechanical properties through hardness and Young modulus ratio (H/E) were determining by nanoindentation while the cross-linking degree has been estimated by coupling ToF-SIMS measurements and PCA treatment. In our experimental window, the cross-linking doubles and the H/E ratio increases from 0.06 to 0.08 when PRF increases from 60 to 280 W.
Additionally, the studies of the film and plasma chemistries allowed proposing a fragmentation pattern of the precursor depending on the experimental conditions