Conveners
DN2020. Soft Matter: Part 1/2
- Walter Richtering (RWTH Aachen)
DN2020. Soft Matter: Part 2/2
- Regine von Klitzing (TU Darmstadt)
Microgels are macromolecular networks swollen by the solvent they are dissolved in. They are unique systems that are distinctly different from common colloids, such as, e.g., rigid nanoparticles, flexible macromolecules, micelles or vesicles. When swollen, they are soft and have a fuzzy surface with dangling chains and the presence of cross-links provides structural integrity. They find...
Cellulose nanofibrils (CNF) have proven their strengths in conductive and transparent films. A promising route for fabricating porous CNF films on large scale is spray deposition using water-based technologies; the resulting porous CNF templates are excellent candidates to infiltrate conductive polymers for functionalization. We used poly(3,4-ethylenedioxythiophene) polystyrene sulfonate...
The diblock copolymer PMMA-b-PNIPAM forms micelles in solution that feature a permanently hydrophobic core and a thermo-responsive shell. While a typical shell collapse transition can be induced via a temperature stimulus at the LCST, the PNIPAM block is also sensitive to the composition of the surrounding solvent. Although water and organic cosolvents individually act as good solvents to the...
Phase separation in biological systems is a path for the formation of cellular organelles[1]. To understand the dynamic properties of these compounds we studied a protein solution model system during the phase separation with neutron spin-echo and back scattering spectroscopy as well as with small angle scattering. The phase separation for the investigated sample occurs for temperatures below...
The surface properties of oppositely charged polyelectrolyte/surfactant mixtures play an important role in colloidal dispersions (foams, emulsions) e.g. for cosmetics, cleaning products and in food technology.
Extensive research on such mixtures was already performed with the focus on different polyelectrolytes as well as surfactants. However, the influence of the ionic strength is still...
Novel block copolymers consisting of two anionic polyelectrolyte blocks [NaPA and NaPSS] have been synthesized. In the presence of certain amounts of divalent cations such as Calcium, Strontium and Barium, supramolecular structures are formed. The overall size and molecular weight of these structures have been obtained by combined static and dynamic light scattering (SLS & DLS). Via...
Stimuli-responsive polymers in aqueous solution form mesoglobules in the two-phase region of the temperature-pressure phase diagram. While the formation of mesoglobules has been amply studied [1], their dissolution and associated structural changes are hardly explored. To elucidate the kinetics of chain swelling and mesoglobule disintegration in a semi-dilute aqueous solution of the...
In the pretreatment of wood it is essential to apply mild conditions for extracting oligomeric cellulose and possibly lignin that can be used for a variety of environmentally friendly products such as polymers. For this, ionic liquids are ideal due to their mixture of polar and non-polar character, which makes them swelling the wood until it bursts to a rather fluffy material. Using small...
Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) results on very large poly(ethylene-oxide) (PEO) rings in the melt are presented [1,2]. The ring conformation demonstrate a clear signature of the theoretically predicted elementary loops. Their size is in the range of an entanglement strand for linear PEO melts and they are characterized by Gaussian statistics. The ring chain...
Wormlike micelles exhibit a unique viscoelastic behavior, which has been investigated intensely in the past decades, experimentally as well as by theoretical calculations [1,2]. Within our studies we explore the self-assembled structure and the flow behavior of wormlike micelles formed by mixing a short-chained C${}_8$ cationic surfactant and the sodium salts of omega-9 fatty acids [3]. Within...
