## 1 Introduction  
The development of surfaces that resist the adhesion and colonization of microbes is an ongoing industrial and academic research topic for applications concerning things of everyday usage, and it is of crucial importance in the biomedical environment. Many different approaches have been attempted to create antimicrobial materials [1; 2; 3], such as surface modification by plasma technique [4; 5], synthesis of composites formed by a polymer and inorganic particles as biocidal agents [6], synthesis of polymers bearing antibacterial groups in their backbone or chain ends [7], and polymers containing a small biocide molecule that is released in appropriate conditions [8]. In an aquatic environment, biofouling can cause substantial economic losses for many industrial sectors (e.g., sensors, shipping [9], and aquaculture [10]), due to the development of microscopic and macroscopic organisms on submerged surfaces. A key step for the consolidation of these communities is the adsorption of macromolecules (e.g., proteins) and the successive formation of a biofilm of microorganisms, composed of an organic matrix (primarily polysaccharide material) with bacteria, fungi, and microalgae, mainly diatoms. The demand for environmentally-friendly systems to prevent the formation of biofilms and control the fouling on surfaces has urgently increased in the last decade, due to environmental constraints and new regulations (for recent reviews see [PERSON] _et al._[11], [PERSON] _et al._[12]). Most traditional and now banned antifouling materials typically contained biocidic agents that were ultimately released in the environment. New approaches for the development of environmentally-friendly antifouling coatings [12] rely on the absence of any release of toxic agents in the environment [13]. In the polymer synthesis field and more widely in the industrial production of plastics, an emerging need/trend is to replace petroleum-derived monomers with the same or analogous ones derived from natural resources [14], in order to produce the same objects but starting from raw materials from renewable sources such as corn, potatoes, sugarcane, and trees [15]. Even if most brands are proud to present their bioplastic packaging to the customers, the latter are rarely aware that the legislation allows calling \"bioplastic\" a material that is only 20%-30% derived from a natural resource, while the remaining percentage comes from identical fossil-derived monomers. Moreover, the use of land to grow crops destined for industrial applications and not for alimentation has already led to aberrations, as in Brazil or Indonesia, where farmers have cut down rainforests to plant crops for the production of biodiesel, with the additional consequence that the prices of traditional crops have risen and not all the population can afford to pay more for food. In the present work, the societal needs of having antibacterial/antifouling and biosourced materials have been combined by synthesizing bioactive films from natural rubber (NR) derived functional oligomers. In our laboratory a methodology has been optimized to cut the polyisoprene chains of natural rubber into telechelic oligomers that bear functional groups at the chain ends, which allows performing further chemical reactions. Natural rubber is not a crop used for food, therefore its use does not present the inconvenience mentioned before; its production is already stable and well established, as it is used for many mass produced goods. In a previous work [16], various formulations were prepared to generate polymeric films using different NR oligomers bearing quaternary ammonium groups as bioactive functions as well as polymerizable groups. It emerged that the presence of oligomers containing one or three quaternary ammonium groups increased the antimicrobial activity in comparison to coatings that did not contain them.