| 1. |
- Gupta, Sudipta, et al.
(author)
-
Validity of the Stokes-Einstein Relation in Soft Colloids up to the Glass Transition
- 2015
-
In: Physical Review Letters. - 1079-7114. ; 115:12
-
Journal article (peer-reviewed)abstract
- We investigate the dynamics of kinetically frozen block copolymer micelles of different softness across a wide range of particle concentrations, from the fluid to the onset of glassy behavior, through a combination of rheology, dynamic light scattering, and pulsed field gradient NMR spectroscopy. We additionally perform Brownian dynamics simulations based on an ultrasoft coarse- grained potential, which are found to be in quantitative agreement with experiments, capturing even the very details of dynamic structure factors S(Q, t) on approaching the glass transition. We provide evidence that for these systems the Stokes-Einstein relation holds up to the glass transition; given that it is violated for dense suspensions of hard colloids, our findings suggest that its validity is an intriguing signature of ultrasoft interactions.
|
|
| 2. |
- Jakob, Michael, et al.
(author)
-
How trade policy can support the climate agenda
- 2022
-
In: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 376:6600, s. 1401-1404
-
Journal article (peer-reviewed)abstract
- Economic analysis has produced ample insights on how international trade and climate policy interact. Trade presents both opportunities and obstacles, and invites the question of how domestic climate policies can be effective in a global economy integrated through international trade. Particularly problematic is the potential relocation of production to regions with low climate standards. Measures to level the playing field, such as border carbon adjustments (BCAs), may be justified for specific emissions-intensive and trade-exposed sectors but need to be well-targeted, carefully navigating tensions that can arise between the desire to respect global trade rules and the need to elaborate and implement effective national climate policies. The conformity of specific trade measures with international trade and climate change law is not entirely clear. Yet, clarity is needed to ensure that the industry actors affected will find the rules predictable and be able to adhere to them.
|
|
| 3. |
- König, Nico, et al.
(author)
-
Spherical Micelles with Nonspherical Cores : Effect of Chain Packing on the Micellar Shape
- 2020
-
In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; , s. 10686-10698
-
Journal article (peer-reviewed)abstract
- Self-assembly of amphiphilic polymers into micelles is an archetypical example of a "self-confined"system due to the formation of micellar cores with dimensions of a few nanometers. In this work, we investigate the chain packing and resulting shape of Cn-PEOx micelles with semicrystalline cores using small/wide-angle X-ray scattering (SAXS/WAXS), contrast-variation small-angle neutron scattering (SANS), and nuclear magnetic resonance spectroscopy (NMR). Interestingly, the n-alkyl chains adopt a rotator-like conformation and pack into prolate ellipses (axial ratio ϵ ≈ 0.5) in the "crystalline"region and abruptly arrange into a more spheroidal shape (ϵ ≈ 0.7) above the melting point. We attribute the distorted spherical shape above the melting point to thermal fluctuations and intrinsic rigidity of the n-alkyl blocks. We also find evidence for a thin dehydrated PEO layer (≤1 nm) close to the micellar core. The results provide substantial insight into the interplay between crystallinity and molecular packing in confinement and the resulting overall micellar shape.
|
|
