Type 100 qs

Particle sizes were determined using dynamic light scattering (instrument: Zetasizer from Malvern, Worcestershire, UK) with a quartz glass cuvette (Hellma Analytics, Type 100 QS, Müllheim, Germany). Per sample, 3 measurements were performed. To investigate the influence of sonication on particle size and distribution, the samples were additionally treated with an ultrasonic sonotrode for 2 min before the measurement.
To yield a dry powder, about 2 mL of the suspension was first stored in a vial at 80 °C for 2 h in a muffle oven and then stored in a vacuum desiccator for at least 3 days. A few milligrams were sufficient to enable Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). For the TGA measurements, the powder samples were heated to 700 °C under atmospheric conditions and the mass loss was determined.

Polystyrene-block-polyacrylic acid (PS-b-PAA, batch: MKBQ5839V) was purchased from Sigma Aldrich (Steinheim, Germany). The degree of polymerization of PS is 275 and of PAA 30, as stated by the manufacturer. The molecular weights (M_n) and the polydispersity index (PDI) of PS-b-PAA are summarized in Table 1.
Deionized water was used as the selective solvent for the hydrophobic part (polystyrene). Tetrahydrofuran (THF, for HPLC, not stabilized) and 1,4-dioxane (for HPLC, not stabilized) from Carl Roth (Karlsruhe, Germany) were utilized as good solvents for PS-b-PAA.
Filters were used for microscopy (Whatman^® Nuclepore™ track-etched polycarbonate membranes, with pore diameters of between 0.2 µm and 2.0 µm, Dassel, Germany). A quartz glass cuvette (Hellma Analytics, Type 100 QS, Müllheim, Germany) with a layer thickness of 10 mm and a nominal volume of 3.5 mL was used for dynamic light scattering measurements.