## 1 Introduction  
Polymer deposition is a current hot topic in research, with numerous applications in everyday life such as biomedical, environmental, packaging or corrosion-protective coatings [1]. Different techniques are used for coating material surfaces with functional organic films, such as direct chemical grafting, ultraviolet-induced polymerization, self-assembled monolayers or plasma-enhanced chemical vapor deposition (PECVD) [2, 3, 4, 5]. Commonly referred to as plasma polymerization, PECVD has attracted considerable attention from both academic and industrial research [6]. Unlike conventional techniques [7], plasma-polymerized films show distinct features. The resulted polymer-like films are usually branched, highly cross-linked, insoluble and pinhole-free and adhere well to most substrates [1, 8]. Furthermore, plasma polymerization does not involve the use of solvents or catalysts, and it is scalable and independent of the nature of the substrate. These featuresresult from a variety of fundamental events occurring in the plasma volume as well as at the plasma-material interface and are triggered by plasma characteristics such as particle density, collision frequency, particle mean kinetic energy and chemical active species. In addition to the intrinsic polymer properties, the plasma parameters can be adjusted to alter the polymer surface as well, through a variety of procedures such as etching, functionalization and cross linking [1]. Among the various plasma sources used in PECVD, the dielectric barrier discharge (DBD) is one of the most versatile and simple to implement. Typically, the polymer precursor is introduced into the discharge region as soluble polymer aerosols or monomer vapors, which will then be activated and fragmented upon passing through the plasma discharge area, generating the film-forming species. The strategy of using the vapors of some macromolecules (aerosols) proved effective in obtaining highly adherent and pinhole-free thin films to protect the substrate against environmental influences. For instance, the injection of poly(ethylene glycol)-poly(vinyl alcohol) copolymer aerosols in a DBD was used for the deposition of ultrathin polymer films (20 nm in thickness) aiming at the fabrication of polyolefin adhesion-promoting layers [9]. Conversely, by introducing monomer vapors into a DBD plasma, the fragmentation and random recombination of the generated species, in conjunction with the processes performed on the substrate (e.g., UV irradiation, well-known to enhance radical polymerization, and ion bombardment of the growing film) [10], enhance cross linking and, as a result, the stability of the obtained plasma-polymerized film [11]. However, the unreasonable increase in the power delivered to the discharge can result in excessive monomer fragmentation, which in turn, through the activation and random recombination of the generated species, leads to the growth of a plasma-polymerized film whose composition is not representative of the starting monomer and even to the deposition of inorganic films [12]. As a result, DBD plasma polymerization entails a complex panel of physical and chemical processes, starting with the fragmentation of the injected precursors (monomers or some macromolecules in aerosol form) caused by collisions with energetic particles, then random recombination and again fragmentation, diffusion and finally condensation to substrate [13]. Plasma-polymerized (pp-PEG) films are the most widely used group of materials that present a hydrophilic character with remarkable resistance to biofouling [14; 15]. PEG was accepted for clinical studies and in vivo applications due to its hydrophilicity, immunogenicity and non-toxicity [16; 17; 18; 19]. The reduction in protein and cell adhesion was tested for pp-PEG films obtained on different substrates. Although these features can be further enhanced by increasing their surface area, its wide spread in applications depends on the development of new techniques to obtain pp-PEG films with a porous morphology.