## 4 Passive Anti-Biofouling Nanoc Coatings
### Combined Passive Strategies  
Neither of the two \"fouling resistance\" and \"fouling release\" strategies can render antibiofilm coatings with excellent antifouling performances by itself.  
Therefore, in order to achieve a synergic antifouling effect, scientists have combined both \"fouling resistant\" and \"fouling release\" passive mechanisms in the same unique polymeric nanostructured material. In an illustrative example, [PERSON] et al. [148] developed an amphiphilic pentablock copolymer by modifying an amphiphilic pluronic F127 triblock copolymer of ABA type composed of two-terminal hydrophilic PEG segments (A blocks) covalently interlinked by a hydrophobic poly(propylene oxide) (PPO) B block. The terminal \"fouling resistant\" hydrophilic poly(ethylene oxide) blocks were further extended through two covalently attached short low surface energy \"fouling release\" polyddimethylsiloxane (PDMS) segments to obtain an amphiphilic PDMS-PEG-PPO-PEG-PDMS block copolymer, as shown in Figure 6. The amphiphilic F127-PDMS block copolymer was further used to prepare nanocomposite membranes by blending with hydrophobic polyethersulfone (PES). The antifouling membrane was fabricated by the non-solvent induced phase separation method (NIPS) [112]. Generally, during the NIPS process, an amphiphilic block copolymer undergoes spontaneous self-assembly at the water/membrane interface, providing a surface extensively covered by the hydrophilic segments and being anchored with the hydrophobic block to the hydrophobic matrix PES polymer. So, the hydrophilic PEG blocks freely segregate onto the water/membrane interface, which is a process that would be impossible for the non-polar low surface energy PDMS segments due to unfavourable thermodynamics. However, the peculiar chemical structure of the amphiphilic F127-PDMS block copolymer allows for \"forced surface segregation\" of the hydrophobic non-polar PDMS segments. The short terminal PDMS segments being covalently linked to the spontaneously surface segregated hydrophilic PEG blocks are being dragged by the later rendering the membrane surface with \"fouling release\" properties in addition to the \"fouling resistance\" properties imparted by the hydrophilic PEG segments. The described synergic strategy is based on the pioneering work of [PERSON]. [PERSON] and co-workers were the first to report the fabrication of antifouling coatings with tunable surface morphologies and topographies based on amphiphilic cross-linked polymeric networks formed in situ from phase-segregating mixtures of incompatible polymeric precursors, namely hydrophobic hyperbranched fluoropolymers (HBFPs) of various polydispersity indexes ranging between 1.8 and 2.4 and hydrophilic bis(3-aminopropyl)-terminated poly(ethylene glycol) [149; 150]. The cross-linked network coatings were prepared on glass substrates, functionalised by 3-aminopropyltriethoxysilane. The surface compositions, morphologies, and topographies of the amphiphilic antifouling coatings depend on the degree of cross-linking, which in turn could be controlled by varying the weight ratio between HBFPs and terminal amine-functionalised PEG used for cross-linking with HBFPs through the nucleophilic aromatic substitution of fluorine atoms.