## Results  
### LP Plasma Deposition of Differently Cell-Repulsive Coatings  
This part of the research aims to demonstrate how, by working at low pressure, it is possible to finely modulate cell-adhesion by using both strategies, 1 (i.e., changing input power) and 2 (i.e., mixing monomers with different typologies of cell-adhesive and cell-repulsive motifs), explained earlier in Figure 1. VAc was mixed with DEGDME in order to modulate the cell-repulsive character of the resulting PEO-like coatings as a function of the relative amount of ether and ester groups in the final structure of deposited coatings. As shown in Figure 2, when different VAc/DEGDME ratios are used to feed the deposition process (i.e., strategy 2 of Figure 1), the chemical composition of the bulk of the deposited coating changes in terms of a decrease in the contribution centered at 1100 cm\({}^{-1}\) (C--O--C stretching), and a gradual increase in the contribution at 1723 cm\({}^{-1}\) (C=O stretching), as the VAc content in the feed increases. Low input power and high-pressure values (i.e., soft plasma conditions) were chosen to guarantee careful control over process conditions. The low energy and soft ion bombardment could, in principle, enable the breaking of labile or double bonds which are characterized by a higher reactivity, without causing significant dissociation of the rest of the molecule [5]. In this case, the chemical structure of the deposited polymer closely resembles that of polymer analogs obtained by conventional radical polymerization processes. The co-presence of ether and carbonyl groups in the coatings confirm that, as expected by the experimental conditions used, a high monomer structure retention is obtained in the coating. All coatings deposited with a flow of DEGDME higher than 0.5 sccm appear sticky and poorly adhering to the underlying substrate. This effect could be due to a combination of milder conditions used (i.e., low input power value) for the process, and the condensation of the scarcely volatile DEGDME monomer in the reactor during the process at high flow rates. Moreover, the high deposition rate of VAc, and the absence of carrier gas, can further contribute in synthesizing a poorly cross-linked coating containing long hydrogel-like chains [15]. To guarantee a correct balance between the retention of the functional groups and a certain cross-linking degree (i.e., non-sticking polymers), the flow of DEGDME was kept constant at 0.5 sccm, while that of the VAc that polymerizes easily was fixed at 4.5 sccm. Thus, from now on, when we speak about coatings obtained by VAc/DEGDME mixtures, we will refer only to those obtained with a VAc/DEGDME ratio of 4.5/0.5. Coatings obtained from DEGDME only indeed were deposited with 0.5 sccm of DEGDME in mixture with Ar [5] to confer the correct coating cross-linking and, at the same time, keep the ether functionalities in the coating. In Figure 3 are reported the FTIR spectra acquired on coatings deposited at different input power values from only DEGDME, only VAc, and from a VAc/DEGDME mixture at 4.5/0.5 ratio. The deposition from DEGDME allows obtaining a coating with an enhanced stretching peak of the ether groups centered at 1100 cm\({}^{-1}\), usually reported for conventional PEO polymers. The absence of a shift to higher wavenumbers for coatings deposited at low power (red spectrum of Figure 3a) demonstrates that such coatings are characterized by a not amorphous state of the macromolecular segments that is, on the contrary, generally typical for plasma polymers. This finding allows assessing  
Figure 2: Fourier-transform infrared spectroscopy (FTIR) spectra acquired for plasma polymers obtained at 5 W and 53 Pa for 60 min from a feed composed by mixtures of VAc/DEGDME at different ratios (i.e., feed total flow 5 sccm): (**a**) 5/0; (**b**) 4.5/0.5; (**c**) 4/1; (**d**) 3/2; (**e**) 1/4; (**f**) 0/5. that, working at low power values, the experimental conditions reported in this paper enables the deposition of plasma polymers very similar to that of conventional PEO.