TY  - JOUR
AU  - Burger, Nikolaos A.
AU  - Meier, G.
AU  - Bouteiller, Laurent
AU  - Loppinet, Benoit
AU  - Vlassopoulos, Dimitris
TI  - Dynamics and Rheology of Supramolecular Assemblies at Elevated Pressures5241
JO  - The journal of physical chemistry  / B
VL  - 126
IS  - 35
SN  - 1089-5647
CY  - Washington, DC
PB  - Soc.
M1  - FZJ-2022-03442
SP  - 6713 - 6724
PY  - 2022
AB  - A methodology to investigate the linear viscoelastic properties of complex fluids at elevated pressures (up to 120 MPa) is presented. It is based on a dynamic light scattering (DLS) setup coupled with a stainless steel chamber, where the test sample is pressurized by means of an inert gas. The viscoelastic spectra are extracted through passive microrheology. We discuss an application to hydrogen-bonding motif 2,4-bis(2-ethylhexylureido)toluene (EHUT), which self-assembles into supramolecular structures (tubes and filaments) in apolar solvents dodecane and cyclohexane. High levels of pressure (roughly above 20 MPa) are found to slow down the terminal relaxation process; however, the increases in the entanglement plateau modulus and the associated persistence length are not significant. The concentration dependence of the plateau modulus, relaxation times (fast and slow), and correlation length is practically the same for all pressures and exhibits distinct power-law behavior in different regimes. Within the tube phase in dodecane, the relative viscosity increment is weakly enhanced with increasing pressure and reaches a plateau at about 60 MPa. In fact, depending on concentration, the application of pressure in the tube regime may lead to a transition from a viscous (unentangled) to a viscoelastic (partially entangled to well-entangled) solution. For well-entangled, long tubes, the extent of the plateau regime (ratio of high- to low-moduli crossover frequencies) increases with pressure. The collective information from these observations is summarized in a temperature–pressure state diagram. These findings provide ingredients for the formulation of a solid theoretical framework to better understand and exploit the role of pressure in the structure and dynamics of supramolecular polymers.
LB  - PUB:(DE-HGF)16
C6  - 36018571
UR  - <Go to ISI:>//WOS:000849329000001
DO  - DOI:10.1021/acs.jpcb.2c03295
UR  - https://juser.fz-juelich.de/record/909821
ER  -