Sorption of Hydrophobic Organic Compounds by Aqueous Latexes

Abstract

Summary: Optical absorption measurements are used for the first time to investigate the uptake of pure organic solvents or solutions by latex particles. Sorption into glassy polymer particles is a two‐stage process with distinctly different characteristic times, which reflects that an initial softening of the outer particle layer facilitates further uptake. The sorption of solutions containing highly water‐insoluble compounds allows the preparation of composite nanoparticles, which are hardly accessible by other routes.Photograph of the neat 100 nm latex (right) particles and the particles after dying by sorption with the hydrophobic pigment Sudan IV (left).magnified imagePhotograph of the neat 100 nm latex (right) particles and the particles after dying by sorption with the hydrophobic pigment Sudan IV (left).

Features of Emulsion Polymerization – How Does the Monomer Move from the Droplets into the Latex Particles?

“…Case C2 is a situation where due to the only gentle stirring, the latex particles contact repeatedly the swelling agent layer and imbibe, particularly during the periods of closed contact, swelling agent and hydrophobic matter dissolved therein. This was proven with in‐line UV‐vis absorption measurements described in .…”

“…That both of these emulsification processes contribute is proven by the experimentally observed increase in swelling while applying only low stirring rates which do not lead to droplet formation but only cause mixing in the aqueous phase (cf. Figure and experiments described in). Under such conditions only advection of the aqueous phase happens and the components dissolved or dispersed in it continuously contact the stationary phase which is in the experiments described here the polymer rod in the confinement hit by the spontaneously generated drops of swelling agent and in the experiments described in the oil phase hit by the latex particles.…”

“…Figure and experiments described in). Under such conditions only advection of the aqueous phase happens and the components dissolved or dispersed in it continuously contact the stationary phase which is in the experiments described here the polymer rod in the confinement hit by the spontaneously generated drops of swelling agent and in the experiments described in the oil phase hit by the latex particles. During these collisions, mass transfer happens which most convincingly is proven by the inclusion of super‐hydrophobic Hostasol Yellow 3G in the polymer.…”

Heterophase Polymerization as Synthetic Tool in Polymer Chemistry for Making Nanocomposites

“…If the organic liquid that is a solvent for the polymer contains a hydrophobic dye such as Sudan IV, Solvent Blue, or Hostasol Yellow the polymer particles become colored. [25] This proves that swelling is highly cooperative in nature which means that not only the solvent is transported into the polymer particles but also the waterinsoluble solute. It was experimentally proven by means of UV-microscopy that polystyrene particles take up poly(methyl methacrylate-co-pyrenemethacrylate).…”

Adaption of the Mechanism of Emulsion Polymerization to New Experimental Results

“…[17] Radicals and monomers are for emulsion polymerizations of particular importance. Despite the actual situation that the uptake-mechanism of monomers and radicals is considered differently there are general principles involved which have to be considered.…”