Director dynamics in liquid-crystal physical gels.

Soft Matter

Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Blvd., Pasadena, California, USA.

Published: July 2007

Nematic liquid-crystal (LC) elastomers and gels have a rubbery polymer network coupled to the nematic director. While LC elastomers show a single, non-hydrodynamic relaxation mode, dynamic light-scattering studies of self-assembled liquid-crystal gels reveal orientational fluctuations that relax over a broad time scale. At short times, the relaxation dynamics exhibit hydrodynamic behavior. In contrast, the relaxation dynamics at long times are non-hydrodynamic, highly anisotropic, and increase in amplitude at small scattering angles. We argue that the slower dynamics arise from coupling between the director and the physically associated network, which prevents director orientational fluctuations from decaying completely at short times. At long enough times the network restructures, allowing the orientational fluctuations to fully decay. Director dynamics in the self-assembled gels are thus quite distinct from those observed in LC elastomers in two respects: they display soft orientational fluctuations at short times, and they exhibit at least two qualitatively distinct relaxation processes.

Download full-text PDF

Source
http://dx.doi.org/10.1039/b700871fDOI Listing

Publication Analysis

Top Keywords

orientational fluctuations
16
short times
12
director dynamics
8
relaxation dynamics
8
long times
8
director
5
times
5
dynamics liquid-crystal
4
liquid-crystal physical
4
gels
4

Similar Publications

Background: Caribbean populations face complex health issues related to diet and food security as they undergo a rapid nutrition transition, resulting in some of the world's highest number of premature deaths from noncommunicable diseases (NCDs). Despite policy efforts to promote local and regional food consumption, reliance on food imports remains high with many Caribbean countries importing more than 80% of their food from larger economies. Previous regional research revealed the importance of food sharing practices in the Caribbean, with implications for the consumption of local foods, food security, and community resilience against climate change.

View Article and Find Full Text PDF

The milk urea content is influenced by a large variety of factors, including the quantity and quality of protein fed, its balance with energy, diurnal fluctuations, management, season, analysis method, and also individual cow factors which include the health status of the cow. Aim of this study was to investigate the effects of metabolic disorders (ketosis, ruminal acidosis; indicated by the fat-protein-content of the milk) as well as high somatic cell counts and udder diseases on the milk urea content of dairy cows from different regions and farms across Germany. For this purpose, 5 independent data sets which contain information derived from monthly milk recordings (data sets A (6,140,342 test-data in 2015), data set D (439,767 test-data in 2020-2023), data set E (399,279 test-data in 2019-2020)) in combination with the differential somatic cell count (DSCC) in data set D and E, or individual recordings of daily feed and energy intake and milk analysis (data set B (58,235 test-data in 2014-2017) and data set C (352,346 test-data in 2018-2021)), were analyzed.

View Article and Find Full Text PDF

Enhanced Dielectric Energy Storage Performance of Polyimide/γ-GaO Nanocomposites under Dual Trap Mechanisms.

ACS Appl Mater Interfaces

December 2024

Sauvage Laboratory for Smart Materials, The School of Integrated Circuit, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.

The rapid development of advanced electronics, hybrid vehicles, etc. has imposed heightened requirements on the performance of polymer dielectrics. However, the energy density () of polymer dielectrics significantly decreases due to increased leakage current and dielectric loss under high temperatures and high electric fields.

View Article and Find Full Text PDF

Dielectric properties of nanoconfined water.

J Chem Phys

December 2024

Solid State and Structural Chemistry Unit, Indian Institute of Science, C V Raman Road, Bengaluru, Karnataka 560012, India.

The dielectric function of a dipolar liquid exhibits a strong wavenumber dependence in the bulk homogeneous state. Such a behavior seems to suggest the possibility of a strong system size dependence of the dielectric constant (DC) of a nanoconfined liquid, although details have been revealed only recently. The dielectric properties of nanoconfined water, indeed, show a marked sensitivity not only to the size and shape (dielectric boundaries) of confinement but also to the nature of surface-water interactions.

View Article and Find Full Text PDF
Article Synopsis
  • Antibiotics like Ciprofloxacin, tetracycline, and Tobramycin are widely used but can lead to antibiotic resistance when their residues enter the environment.
  • Traditional monitoring methods for these antibiotics, such as LC-MS, are costly and complex, while nanoscale field-effect transistors (FETs) offer quick and sensitive alternatives but struggle with consistency in performance.
  • The study presents an innovative approach using thermally reduced graphene oxide FETs on printed circuit boards, achieving ultra-sensitive detection of antibiotics at femtomolar levels with machine learning, enabling effective monitoring of water contamination.
View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!