DLS Setup for in Situ Measurements of Photoinduced Size Changes of Microgel-Based Hybrid Particles.

Photoinduced size changes in microgel particles loaded with gold nanoparticles (AuNPs) were investigated with an extended multiangle dynamic light scattering (DLS) setup. The DLS setup was equipped with a conventional laser (λ = 633 nm) to determine the microgel particle size. Additionally, a laser (λ = 532 nm) is installed to study the photoresponsive behavior of the AuNP-microgel hybrids.

Communication: Light driven remote control of microgels' size in the presence of photosensitive surfactant: Complete phase diagram.

Here we report on a light triggered remote control of microgel size in the presence of photosensitive surfactant. The hydrophobic tail of the cationic surfactant contains azobenzene group that undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. We have investigated light assisted behaviour and the complex formation of the microgels with azobenzene containing surfactant over the broad concentrational range starting far below and exceeding several times of the critical micelle concentration (CMC).

Photosensitive microgels containing azobenzene surfactants of different charges.

We report on light sensitive microgel particles that can change their volume reversibly in response to illumination with light of different wavelengths. To make the anionic microgels photosensitive we add surfactants with a positively charged polyamine head group and an azobenzene containing tail. Upon illumination, azobenzene undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant.

Interfacial properties of Quillaja saponins and its use for micellisation of lutein esters.

Natural food colourants, colouring foods and bioactive food ingredients need to be solubilised for their incorporation in food. Aim of the present study was to investigate the micelle-forming properties of saponins from Quillaja saponaria Mollina (QS) in order to solubilise a lutein ester extract for its incorporation in food matrices. QS showed a high surface activity and functionality with respect to micellisation as derived from interfacial tension measurements and subsequent data fitting to the classical Frumkin model.

Two-Dimensional Aggregation and Semidilute Ordering in Cellulose Nanocrystals.

The structural properties and aggregation behavior of carboxymethylated cellulose nanocrystals (CNC-COOH) were analyzed with small angle neutron scattering (SANS), transmission electron microscopy (TEM), atomic force microscopy (AFM), and dynamic light scattering (DLS) and compared to sulfuric acid hydrolyzed cellulose nanocrystals (CNC-SO3H). The CNC-COOH system, prepared from single carboxymethylated cellulose nanofibrils, was shown to laterally aggregate into 2D-stacks that were stable both in bulk solution and when adsorbed to surfaces. CNC-SO3H also showed a 2D aggregate structure with similar cross sectional dimensions (a width to height ratio of 8) as CNC-COOH, but a factor of 2 shorter length.