Charged poly(N-isopropylacrylamide-co-methacrylic acid) [P(NiPAM-co-MAA)] microgels can stabilize thermo- and pH-sensitive emulsions. By placing charged units at different locations in the microgels and comparing the emulsion properties, we demonstrate that their behaviors as emulsion stabilizers are very different from molecular surfactants and rigid Pickering stabilizers. The results show that the stabilization of the emulsions is independent of electrostatic repulsion although the presence and location of charges are relevant. Apparently, the charges facilitate emulsion stabilization via the extent of swelling and deformability of the microgels. The stabilization of these emulsions is linked to the swelling and structure of the microgels at the oil-water interface, which depends not only on the presence of charged moieties and on solvent polarity but also on the microgel (core-shell) morphology. Therefore, the internal soft and porous structure of microgels is important, and these features make microgel-stabilized emulsions characteristically different from classical, rigid-particle-stabilized Pickering emulsions, the stability of which depends on the surface properties of the particles.

Oil on troubled waters: Stimuli-sensitive emulsions have been used to prepare temperature- and pH-responsive microgels. The emulsion stability at oil-water interfaces is not governed by the particle packing density, and structural changes induced by the interface lead to connections between the individual microgels (see picture; scale bar 1 microm), which behave very differently compared to solid-particle-stabilized emulsions.

Ordnung im Ölfilm: Mithilfe von reizempfindlichen Emulsionen wurden temperatur‐ und pH‐responsive Mikrogele entwickelt. Die Emulsionsstabilität an den Öl‐Wasser‐Grenzflächen wird nicht durch die Packungsdichte der Partikel bestimmt. Durch die Grenzfläche ausgelöste Strukturänderungen führen zur Verknüpfung der Mikrogele (siehe Bild; Maßstab 1 μm), die sich in ihrem Verhalten deutlich von Festpartikel‐stabilisierten Emulsionen unterscheiden.

No abstract

Animal fiber identification in the scanning electron microscope (SEM) using the criterion of cuticle scale edge height (CSH) is a well established method suitable for all stages of textile processing. In his paper, P. A. Tucker ( Textile Res. J. 68, 229-230 (1998)) presents results that lead him to state comprehensively, "fiber identification based on scale heights is misleading for some and probably all chemically treated fibers." After scrutinizing Tucker's evidence in view of specific SEM investigations in the literature and applying a consistent terminology, we conclude that he fails to provide valid evidence against the CSH method for discriminating sheep's wool from specialty fibers. Furthermore, we document changes in fiber surface morphology due to textile processing and discuss their general relevance for wool and specialty fiber analysis.