Comparison of different coating techniques on the properties of FucoPol films

Plasma deposition, liquid flame spray (LFS) and atomic layer deposition (ALD) were used to form inorganic coatings in new exopolysaccharide (FucoPol) biodegradable films. Coated films were characterised in terms of surface, optical and barrier properties in order to evaluate their potential use in food packaging. FucoPol films presented dense and homogeneous surface with instant water contact angle of 95̊. Plasma deposition of perfluorohexane (PFH) on FucoPol surface has not shown significant improvement in the hydrophobic behaviour over the time. The FucoPol coating of SiO₂ nanoparticles deposited by LFS and plasma deposition of PFH have shown higher instant water contact angle (135°) caused by coating surface roughness, but this hydrophobic behaviour was not stable over time. FucoPol films coated only with TiO₂ deposited by ALD and combination of that with plasma deposition of PFH have shown stable water contact angle during time (90̊ and 115̊, respectively), transparency in the same order of magnitude and significantly lower permeability to water vapour (3.45 × 10⁻¹¹ mol/m s Pa and 3.45 × 10⁻¹¹ mol/m s Pa when compared to uncoated films with 5.32 × 10⁻¹¹ mol/m s Pa). Moreover, films coated with TiO₂-PFH have also shown a permeability to oxygen of 1.70 × 10⁻¹⁶ molm/m²s Pa which is 67% lower than uncoated films.