• polysiloxane
• poly(2-oxazoline)
• methacrylic
• heterografted
• antifouling
• amphiphilic

The first part of this thesis work consisted of an extensive review of the literature, mainly focused on the use of poly(2-alkyl-2-oxazoline) (POx)-based systems for the development of amphiphilic copolymers for anti(bio)fouling applications. The second part was devoted to an experimental work divided into two steps. The first one was carried out at the “Laboratory for Surface Science and Technology” at ETH-Zurich, within the ERASMUS program, and was mainly focussed on the synthesis via cationic ring opening polymerization (CROP) of oligo(2-alkyl-2-oxazoline)methacrylate) (ROxnMA, R = methyl and ethyl) with different lengths (n). The second step was, instead, carried out in our laboratory and consisted of the synthesis and characterization of two different classes of heterografted amphiphilic copolymers SiMA-co-ROxnMA by alternatively copolymerizing the same hydrophobic polysiloxane methacrylate monomer (SiMA) with poly(2-methyl-2-oxazoline) (R = Me) or poly(2-ethyl-2-oxazoline) (R = Et) methacrylate comonomers both possessing a n value of about 10 and 20 units on average. A third class of copolymers SiMA-co-PEGnMA containing poly(ethylene glycol) as the hydrophilic side chain, with comparable values of n, was also synthesized as reference samples as amphiphilic PEGMA-based copolymers represent a gold standard for the development of amphiphilic coatings to combat marine biofouling. Controlled RAFT polymerization was chosen for the synthesis of the copolymers, in which the amount of the hydrophilic component ROxnMA or PEGMA was kept similar for each class and intentionally low ( 5 mol%) to prevent its solubilisation in water, but enough for changing the wettability properties of the unmodified hydrophobic SiMA homopolymer. Copolymers were structurally and thermally characterized by 1H NMR/GPC and DSC/TGA, respectively. Their water wettability was found to be higher than that of the SiMA homopolymer films and dependant on the nature of the hydrophilic side chains and their length, generally increasing according to the order PEGMA < EtOx < MeOx and being higher for n  20 than n  10. X-ray photoelectron spectroscopy (XPS) analyses confirmed the presence of the hydrophilic component at the polymer-air interface, in a percentage similar to the theoretical one without a significant excess of the lowest surface energy SiMA component. Copolymer films were also found to undergo surface reconstruction in a different extent depending on the type of the hydrophilic counit, by following an opposite trend with respect to that identified for water wettability.
Amphiphilic copolymers were physically dispersed as surface-active additives into condensation-cure PDMS matrix to produce films with a double layer-geometry, in which the bulk elastomeric mechanical properties and the surface wetting properties could be independently controlled. In any case, water wettability was reduced with respect to the corresponding copolymers because of the presence of PDMS as the predominant component.
Initial biological tests were carried out against two model organisms, namely the diatom Navicula salinicola and the serpulid Ficopomatus enigmaticus. Results suggest that the settlement of F. enigmaticus on films containing SiMA-co-ROxnMAx was lower than those with SiMA-co-PEGnMAx, suggesting a more effective antifouling activity of the more hydrophilic polyoxazoline grafts in general, and the longer ones in particular. The adhesion of cells of N. salinicola was also found to be lower on films containing copolymers with longer hydrophilic chains, even though the different types of hydrophilic components behaved similarly. In addition, more than 75% of diatoms were successfully removed from all the coatings, including the PDMS control, under the action of a very low shear stress of 1 Pa.