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.

A two-step "grafting from" method has been successfully carried out, which is based on the electrografting of polyacrylate chains containing an initiator for the atom transfer radical polymerization (ATRP) of 2-(tert-butylamino)ethyl methacrylate (TBAEMA) or copolymerization of TBAEMA with either monomethyl ether of poly(ethylene oxide) methacrylate (PEOMA) or acrylic acid (AA) or styrene. The chemisorption of this type of polymer brushes onto stainless steel surfaces has potential in orthopaedic surgery. These films have been characterized by ATR-FTIR, Raman spectroscopy, atomic force microscopy (AFM), and measurement of contact angles of water. The polymer formed in solution by ATRP and that one detached on purpose from the surface have been analyzed by size exclusion chromathography (SEC) and (1)H NMR spectroscopy. The strong adherence of the films onto stainless steel has been assessed by peeling tests. AFM analysis has shown that addition of hydrophilic comonomers to the grafted chains decreases the surface roughness. According to dynamic quartz crystal microbalance experiments, proteins (e.g., fibrinogen) are more effectively repelled whenever copolymer brushes contain neutral hydrophilic (PEOMA) co-units rather than negatively charged groups (PAA salt). Moreover, a 2- to 3-fold decrease in the fibrinogen adsorption is observed when TBAEMA is copolymerized with either PEOMA or AA rather than homopolymerized or copolymerized with styrene. Compared to the bare stainless steel surface, brushes of polyTBAEMA, poly(TBAEMA-co-PEOMA) and poly(TBAEMA-co-AA) decrease the bacteria adhesion by 3 to 4 orders of magnitude as revealed by Gram-positive bacteria S. aureus adhesion tests.

Nanostructured niobium oxide (NO) semiconductor is gaining increasing attention as electronic, optical, and electro-optic material. However, the preparation of stable NO nanofilms with reproducible morphology and behavior remains a challenge. 10Here we show a rapid, well-controlled, and efficient way to synthesize NO films with the self-organized columnlike nanostructured morphologies and advanced functional properties. The films are developed via the growth of a nanoporous anodic alumina layer, followed by the pore-directed 15 anodizing of the Nb underlayer. The columns may grow 30-150 nm wide, up to 900 nm long, with the aspect ratio up to 20, being anchored to a thin continuous oxide layer that separates the columns from the substrate. The as anodized films have a graded chemical composition changing from amorphous Nb 2 O 5 mixed with Al 2 O 3 , Si-, and P-containing species in the surface region to NbO 2 in the lower film layer. The post-anodizing treatments result in the controlled 20 formation of Nb 2 O 5 , NbO 2 , and NbO crystal phases, accompanied by transformation from nearly perfect dielectric to n-type semiconductor behavior of the films. The approach allows for the smooth film growth without early dielectric breakdown, stress-generated defects, or destructive dissolution at the respective interfaces, which is a unique situation in the oxide films on niobium. The functional properties of the NO films, revealed to date, allow for potential applications as nanocomposite capacitor dielectrics and active 25 layers for semiconductor gas microsensors with the sensitivity to ethanol and the response to hydrogen being among best ever reported.

Novel copolymer brushes have been synthesized by a two-step "grafting from" method that consists of the electrografting of poly(2-phenyl-2-(2,2,6,6-tetramethyl-piperidin-1-yloxy)-ethylacrylate) onto stainless steel, followed by the nitroxide-mediated radical polymerization of 2-(dimethylamino ethyl)acrylate and styrene or n-butyl acrylate, initiated from the electrografted polyacrylate chains. The grafted copolymers were quaternized in order to endow them with antibacterial properties. Peeling tests have confirmed the strong adhesion of the grafted copolymer onto the stainless steel substrate. Quartz crystal microbalance experiments have proven that fibrinogen adhesion is lower on the hydrophilic quaternized films compared to the nonionic counterpart. Such quaternized copolymers exhibit significant antibacterial activity against the Gram-positive bacteria S. aureus and the Gram-negative bacteria E. coli.

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.%.

505 ContentsIn view of barrier layer application, organic plasma polymer fi lms based on ethyl lactate precursor are studied in terms of crosslinking degree and mechanical properties. Their comparison as a function of the input power reveals a strong infl uence of the cross-linking degree on hardness, creep strain and viscoelastic recovery of the plasma polymer. However, little infl uence on the reduced modulus is found. At the highest power it shows the highest cross-linking leading to a global improvement of the mechanical performance of wear, fracture resistances, hardness, and self-healing capabilities.

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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.