scholarly journals Molecular dynamic heterogeneity in relation to free volume and relaxation dynamics in organic glass-formers: oligomeric cis-1,4-poly(isoprene)

2017 ◽  
Vol 19 (23) ◽  
pp. 15215-15226 ◽  
Author(s):  
H. Švajdlenková ◽  
S. Arrese-Igor ◽  
Z. Nógellová ◽  
A. Alegría ◽  
J. Bartoš
Keyword(s):  
Molecular Dynamic ◽  
Free Volume ◽  
Molecular Rotation ◽  
Organic Glass ◽  
Relaxation Dynamics ◽  
Dynamic Heterogeneity ◽  
Host Medium ◽  
Rotation Dynamics

Herein, a combined study of the molecular rotation dynamics and free volume in cis-1,4-poly(isoprene) using two external probing techniques via ESR and PALS together with relaxation dynamics of the host medium via BDS is presented.

scholarly journals On the Mutual Relationships between Molecular Probe Mobility and Free Volume and Polymer Dynamics in Organic Glass Formers: cis-1,4-poly(isoprene)

Polymers ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 294
Author(s):  
Helena Švajdlenková ◽  
Ondrej Šauša ◽  
Sergey V. Adichtchev ◽  
Nikolay V. Surovtsev ◽  
Vladimir N. Novikov ◽  
...  
Keyword(s):  
Free Volume ◽  
Spin Probe ◽  
Hyperfine Coupling Constant ◽  
Organic Glass ◽  
Molecular Probe ◽  
Positron Annihilation Lifetime ◽  
Broadband Dielectric Spectroscopy ◽  
Relaxation Modes ◽  
Reorientation Dynamics ◽  
In Cis

We report on the reorientation dynamics of small spin probe 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) in cis-1,4-poly(isoprene) (cis-1,4-PIP10k) from electron spin resonance (ESR) and the free volume of cis-1,4-PIP10k from positron annihilation lifetime spectroscopy (PALS) in relation to the high-frequency relaxations of cis-1,4-PIP10k using light scattering (LS) as well as to the slow and fast processes from broadband dielectric spectroscopy (BDS) and neutron scattering (NS). The hyperfine coupling constant, 2Azz′(T), and the correlation times, τc(T), of cis-1,4-PIP10k/TEMPO system as a function of temperature exhibit several regions of the distinct spin probe TEMPO dynamics over a wide temperature range from 100 K up to 350 K. The characteristic ESR temperatures of changes in the spin probe dynamics in cis-1,4-PIP10k/TEMPO system are closely related to the characteristic PALS ones reflecting changes in the free volume expansion from PALS measurement. Finally, the time scales of the slow and fast dynamics of TEMPO in cis-1,4-PIP10k are compared with all of the six known slow and fast relaxation modes from BDS, LS and NS techniques with the aim to discuss the controlling factors of the spin probe reorientation mobility in polymer, oligomer and small molecular organic glass-formers.

Dynamic and free volume aspects of spin probe TEMPO in organic glass formers: Polymer cis-1,4-poly(isoprene)

2018 ◽  
Author(s):  
Helena Švajdlenková ◽  
Ondrej Šauša ◽  
Katarína Čechová ◽  
Josef Bartoš
Keyword(s):  
Free Volume ◽  
Spin Probe ◽  
Organic Glass

Molecular probe dynamics and free volume in organic glass-formers and their relationships to structural relaxation: 1-propanol

2015 ◽  
Vol 28 (1) ◽  
pp. 015101 ◽  
Author(s):  
J Bartoš ◽  
H Švajdlenková ◽  
O Šauša ◽  
M Lukešová ◽  
D Ehlers ◽  
...  
Keyword(s):  
Free Volume ◽  
Structural Relaxation ◽  
Organic Glass ◽  
Molecular Probe

scholarly journals Dynamic Heterogeneity in Ring-Linear Polymer Blends

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 752 ◽  
Author(s):  
Anna F. Katsarou ◽  
Alexandros J. Tsamopoulos ◽  
Dimitrios G. Tsalikis ◽  
Vlasis G. Mavrantzas
Keyword(s):  
Relaxation Times ◽  
Relative Importance ◽  
Relaxation Dynamics ◽  
Dynamic Heterogeneity ◽  
Exponential Functions ◽  
Broad Distribution ◽  
Orientational Relaxation ◽  
Ring Molecules ◽  
Linear Chains ◽  
Molecular Length

We present results from a direct statistical analysis of long molecular dynamics (MD) trajectories for the orientational relaxation of individual ring molecules in blends with equivalent linear chains. Our analysis reveals a very broad distribution of ring relaxation times whose width increases with increasing ring/linear molecular length and increasing concentration of the blend in linear chains. Dynamic heterogeneity is also observed in the pure ring melts but to a lesser extent. The enhanced degree of dynamic heterogeneity in the blends arises from the substantial increase in the intrinsic timescales of a large subpopulation of ring molecules due to their involvement in strong threading events with a certain population of the linear chains present in the blend. Our analysis suggests that the relaxation dynamics of the rings are controlled by the different states of their threading by linear chains. Unthreaded or singly-threaded rings exhibit terminal relaxation very similar to that in their own melt, but multiply-threaded rings relax much slower due to the long lifetimes of the corresponding topological interactions. By further analyzing the MD data for ring molecule terminal relaxation in terms of the sum of simple exponential functions we have been able to quantify the characteristic relaxation times of the corresponding mechanisms contributing to ring relaxation both in their pure melts and in the blends, and their relative importance. The extra contribution due to ring-linear threadings in the blends becomes immediately apparent through such an analysis.

Molecular dynamics and free volume in organic glass-formers: A series of oligomer and polymer 1,4-poly(isoprene)s

2014 ◽  
Vol 602 ◽  
pp. 28-33 ◽  
Author(s):  
J. Bartoš ◽  
H. Švajdlenková ◽  
M. Lukešová ◽  
Y. Yu ◽  
R. Krause-Rehberg
Keyword(s):  
Molecular Dynamics ◽  
Free Volume ◽  
Organic Glass
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