Abstract
The behavior in solution of original structures of amphiphilic partially natural copolymers based on polyoxazoline (POx) (poly(2-methyl-2-oxazoline)) and grape seed vegetable oil derivatives (linear, T- and trident-structure) are investigated. The results show that such systems are found, using dynamic light scattering (DLS), to spontaneously self-organize into monomodal, narrow-size and stable nanoparticles in aqueous medium. The obtained hydrodynamic diameters (Dh) range from 8.6 up to 32.5 nm. Specifically, such size increases strongly with increasing natural block (i.e. lipophilic species) length due to higher hydrophobic interactions (from 10.1 nm for C19 to 19.2 nm for C57). Furthermore, increasing the polyoxazoline (i.e. hydrophilic block) length leads to a moderate linear increase of the Dh-values. Therefore, the first order size effect comes from the natural lipophilic block whereas the characteristic size can be tuned more finely (i.e. in a second order) by choosing appropriately the polyoxazoline length. The DLS results in terms of characteristic size are corroborated using nanoparticle tracking analysis (NTA), and also by atomic force microscopy (AFM) and transmission electron microscopy (TEM) imaging where well-defined, spherical and individual nanoparticles exhibit a very good mechanical resistance upon drying. Moreover, changing the lipophilic block architecture from linear to T-shape and keeping the same molar mass generates a branching and thus a shrinking by a factor of 2 of the nanoparticle volume, as shown by DLS. In this paper, we clearly show that the self-assemblies of amphiphilic block copolymer obtained from grape seed vegetable oil derivatives (sustainable renewable resources) as well as their tunability are of great interest for biomass valorization at the nanoscale level.