Synthese von funktionellen Hybridnanopartikeln und Verkapselung von Aktiv- und Wirkstoffen mittels Miniemulsionspolymerisation

Abstract

The encapsulation of the hydrophobic fragrance 1,2-dimethyl-1-phenyl-butyramide (DMPBA) and the hydrophobic biocide iodopropinylbutyrcarbamate (IPBC), in different homopolymer or acrylic copolymer nanoparticles can easily be obtained using a one-step miniemulsion process. In case of the IPBC a complete encapsulation can be achived by adding an additive which prevents crystallitation of the active compound. It is shown that the hydrophobic compound directly influences the kinetics, the molecular weight, and the morphology of the nanocapsule formation. The release behavior can be tuned by the temperature in relation to the Tg of the polymer which makes these nanocapsules to interesting candidates for temperature-dependent delivery systems. The second part of this thesis discribes the preparation of alkyd-acrylic hybrid polymer dispersion for coating applications with varying alkyd-acrylic ratios and solid contents by in-situ miniemulsion polymerization technique using ultrasound as a high shear technique. The droplet sizes, viscosities, surface tensions and the stability over time of the respective miniemulsions were investigated. The kinetic of the polymerization as well as the influence of the alkyd on the monomer conversion and the molecular weight was determined. The influence of the alkyd/acrylic ratio as well as the monomer composition and the influence of the initiator, the reaction temperature, and the degree of grafting on the polymerization kinetics are investigated. The morphology and the miscibility of the polymer phases inside the polymer-polymer particles are dependent on these characteristics which were determined by TEM, AFM, STED and FRET experiments. The morphology and the resulting fim forming properties of the alkyd/acrylic hybrid particles are affected by factors like the degree of grafting as well as the polymer/polymer composition.