P. Samyn, D. Stanssens
University of Freiburg - Freiburg Institute for Advanced Studies, Germany
pp. 452 - 455
Keywords: vegetable oil, organic nanoparticle, encapsulation, release
Nanoparticle pigments of poly(styrene-maleimide) or SMI have been synthesized containing different vegetable oils that favourably can be applied as a barrier resistant coating against water and oil penetration onto paper substrates and regulate its surface hydrophobicity. The morphology of SMI/oil nanoparticles changes with oil type, having homogeneous spherical shapes (20 to 60 nm) for poly-unsaturated oils, core-shell shapes for mono-unsaturated oils, or containing free oil for the most saturated oils. After coating the dispersion on papers, the thermal oil release has been studied under heating. At low to intermediate NH3 concentrations the progressive release of oil can be followed by diminution and separation of oil-related absorption bands in Raman spectra. At high NH3 concentration, the higher imidisation degree and better thermal stability do not allow for fluent oil release. The oil release improves the coating homogeneity and can be followed by chemical Raman mapping. The dynamics of oil release depends on the initial morphology of the SMI/oil nanoparticles: (i) release from sponge-like structures in presence of soy oil occurs more gradually as a function of temperature due to diffusion processes compared with (ii) release from core-shell type nanoparticles depends more critically on the glass transition temperature (Tg = 176°C).