## 5 Applications
In order to prepare functional materials suitable for producing final products production, it is reasonable to consider the aggregation state of the addressed final products. Moreover, techniques that allow a suitable amount of bionanosystems to be deposited on the material should be selected. Certainly, bionanocomposites should be easily dispersible in the final products. Compatibilizers, as well as specific techniques to graft them on solid surfaces, can allow more effective results, including good homogeneity and addressed properties. In the case of ulvan, possible grafting with polymers was studied by [PERSON] et al. [180]. They grafted a few acrylic monomers onto ulvan through esterification reaction between the hydroxyl groups of ulvan and acryloylchloride. At this point, ulvan was transformed in a macromonomer that could be polymerized with poly(N-isopropylacrylamide). The authors obtained thermosensitive gels quite interesting for biomedical applications. However, the methodology they followed is quite general and may allow ulvan to be grafted on the polymers synthesizable by polyadditions. Thus, this is a route to produce several compatibilizers that may allow ulvan to be incorporated into several polymeric materials, both for liquid (varnishes, coatings, etc... ) or solid applications (tissues, films, etc... ). In general, [PERSON] et al. [181], working on cosmetic applications of ulvan, suggested that the dispersion of ulvan in oil in water emulsions, typical of cosmetic products such as body creams, can be facilitated using specific techniques such as ultrasounds. Interestingly, [PERSON] et al. [182] grafted ulvan on metal surfaces. Ulvan was covalently immobilized on titanium surfaces which had been previously functionalized by self-assembled monolayers of aminoundecyltrimethoxysilane (AUTMS). This latter worked as a primer coating on the metal. Anti-adhesive properties of titanium implants for biomedical applications were improved thanks to the surface grafting of ulvan. On the other hand, inhibition of marine fouling on surfaces has been a critical issue in marine industries, as severe adhesion of marine foulants on the surface of marine vessels eventually leads to increased fuel consumption. Marine fouling resistance was significantly enhanced by ulvan. This aspect was also investigated by [PERSON] et al. [183]. To achieve this, a solid titanium surface was treated with plasma to insert hydroxyl groups by immersion into an ethanol solution of (3-aminopropyl) triethoxysilane (APTES). In situ polycondensation of APTES followed by covalent bond formation with ulvan allowed obtaining monolayer coatings that reduced of 60% the adhesion of diatom on the surface with respect to not-treated surfaces. Membranes based on ulvan suitable for wound dressing applications were developed using a diepoxide (1,4-butanediol diglycidyll ether) cross-linking agent by [PERSON] et al. [184]. In biomedical applications, and specifically in wound care, the use of ulvan hydrogel is also very promising, as recently evidenced by [PERSON] et al. [185] in their review. The authors evidenced the necessity of performing further research on ulvan hydrogel applications and in vivo studies to facilitate a wider use of this material. Figure 12: Schematic representation of the ulvan sources leading to different applications sectors and functional biomaterials.