Primary amine‐based plasma polymer films (NH2‐PPF) were synthesized using plasma polymerization of allylamine in continuous wave (CW) and pulsed radio‐frequency (RF) modes. Plasma chemistry, studied by residual gas analysis mass spectrometry, revealed that the precursor fragmentation is a function of the equivalent power (Peq) dissipated in the discharge, independently of the plasma mode used. X‐ray photoelectron spectroscopy combined with time‐of‐flight secondary ion mass spectrometry suggests as the precursor fragmentation in the plasma increases: (i) a decrease of the primary amine concentration in the NH2‐PPF (%NH2) and (ii) an increase of the cross‐linking degree. For a given Peq, similar to the precursor fragmentation in the plasma, the NH2‐PPF characteristics were found to be independent of the plasma mode used. Therefore, the main advantage of using pulsed RF processes over CW ones is the possibility to work at very low Peq which enables low precursor fragmentation, optimization of %NH2, and reduction of the film cross‐linking degree. The chemical composition and the cross‐linking degree of the NH2‐PPF synthesized by allylamine plasma polymerization can thus be tailored by adjusting the equivalent RF power injected in the plasma.

The pulsed plasma polymerization of allylamine and cyclopropylamine is investigated to study the influence of the precursor chemical structure on the process selectivity toward the primary amine groups. Both systems are compared under similar mean powers injected in the discharges (P mean ). The results reveal an increase in the precursor fragmentation in the plasma and a decrease in the primary amine content of the film (%NH 2 ) as P mean increases. Nevertheless, below a critical P mean value, different behaviors are observed depending on the precursor, cyclopropylamine being less plasma-fragmented than allylamine. As a result, plasma polymer films (PPF) synthesized from cyclopropylamine yield the largest %NH 2 . These results are rationalized with the help of theoretical calculations pointing to a preferential opening of the cyclopropylamine ring structure. Cyclopropylamine activation in the plasma can thus be achieved without fragmentation reactions, leading to a more efficient incorporation of the ÀNH 2 group of the precursor in the PPF.

Methyl isobutyrate is plasma‐polymerized varying the precursor flow rate (Φp), the working pressure (p) and the radiofrequency power injected in the discharge (PRF). Through the use of an experimental design, PRF reveals to be the key parameter regarding the incorporation of oxygen‐based functionalities in the plasma polymer films (PPFs). Combining the use of X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) and principal component analysis (PCA), our results demonstrate that an increase of PRF (i) lowers the incorporation of the precursor ester groups within the PPFs and (ii) amplifies the PPF crosslinking density (χ). A correlation between the PPF physico‐chemistry and the plasma composition is established using residual gas analysis mass spectrometry. It is shown that an increase of PRF increases both the extent of the precursor fragmentation and the production of non‐reactive oxygen‐based species in the plasma that do not contribute to the PPF growth. Incidentally, in the PRF range studied, the total amount of oxygen‐based functionalities incorporated in the PPFs (at.%O) varies from 23.9 to 10.1 at.%.

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In this work, we report on the synthesis of ethyl lactate-based plasma polymer film (ELPPF) by plasma enhanced chemical vapour deposition (PECVD). Using a design of experiments, it appears that, among other, the injected power (P RF ) is the key parameter affecting the ELPPF features. Indeed, we observe a strong decrease of the COO-C/H functionalities (from 12 to 2 at.%) within a limited P RF domain. A more precise analysis of the film chemistry by combining XPS and chemical derivatization reveals that up to 95% of these carboxyl-based functions are esters. On the other hand, we show that the cross-linking degree of the ELPPF can be increased by a factor of two as a function of P RF . This work paves the way for the tailoring of the barrier properties of ELPPF by controlling the ester content and the cross-linking degree of the PPF.