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Title: Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend

Abstract

Spatial compositional heterogeneity strongly influences the dynamics of the A and B components of bulk miscible blends. Its effects are especially apparent in mixtures, such as poly(vinyl methyl ether) (PVME)/polystyrene (PS), where there exist significant disparities between the component glass transition temperatures (Tgs) and relaxation times. The relaxation processes characterized by distinct temperature dependencies and relaxation rates manifest different local compositional environments for temperatures above and below the glass transition temperature of the miscible blend. This same behavior is shown to exist in miscible PS/PVME films as thin as 100 nm. Moreover, in thin films, the characteristic segmental relaxation times t of the PVME component of miscible PVME/PS blends confined between aluminum (Al) substrates decrease with increasing molecular weight M of the PS component. These relaxation rates are film thickness dependent, in films up to a few hundred nanometers in thickness. This is in remarkable contrast to homopolymer films, where thickness confinement effects are apparent only on length scales on the order of nanometers. These surprisingly large length scales and M dependence are associated with the preferential interfacial enrichment - wetting layer formation - of the PVME component at the external Al interfaces, which alters the local spatial blend compositionmore » within the interior of the film. The implications are that the dynamics of miscible thin film blends are dictated in part by component Tg differences, disparities in component relaxation rates, component-substrate interactions, and chain lengths (entropy of mixing).« less

Authors:
 [1];  [2];  [2]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
  2. University of Michigan
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
National Science Foundation (NSF)
OSTI Identifier:
1426643
Report Number(s):
NREL/JA-5A00-71115
Journal ID: ISSN 0024-9297
DOE Contract Number:  
AC36-08GO28308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Macromolecules; Journal Volume: 51; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; aluminum; glass; glass transition; interfaces; relaxation time; substrates; temperature

Citation Formats

Green, Peter, Sharma, Ravi P., and Dong, Ban Xuan. Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend. United States: N. p., 2018. Web. doi:10.1021/acs.macromol.7b02152.
Green, Peter, Sharma, Ravi P., & Dong, Ban Xuan. Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend. United States. doi:10.1021/acs.macromol.7b02152.
Green, Peter, Sharma, Ravi P., and Dong, Ban Xuan. Thu . "Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend". United States. doi:10.1021/acs.macromol.7b02152.
@article{osti_1426643,
title = {Role of Thickness Confinement on Relaxations of the Fast Component in a Miscible A/B Blend},
author = {Green, Peter and Sharma, Ravi P. and Dong, Ban Xuan},
abstractNote = {Spatial compositional heterogeneity strongly influences the dynamics of the A and B components of bulk miscible blends. Its effects are especially apparent in mixtures, such as poly(vinyl methyl ether) (PVME)/polystyrene (PS), where there exist significant disparities between the component glass transition temperatures (Tgs) and relaxation times. The relaxation processes characterized by distinct temperature dependencies and relaxation rates manifest different local compositional environments for temperatures above and below the glass transition temperature of the miscible blend. This same behavior is shown to exist in miscible PS/PVME films as thin as 100 nm. Moreover, in thin films, the characteristic segmental relaxation times t of the PVME component of miscible PVME/PS blends confined between aluminum (Al) substrates decrease with increasing molecular weight M of the PS component. These relaxation rates are film thickness dependent, in films up to a few hundred nanometers in thickness. This is in remarkable contrast to homopolymer films, where thickness confinement effects are apparent only on length scales on the order of nanometers. These surprisingly large length scales and M dependence are associated with the preferential interfacial enrichment - wetting layer formation - of the PVME component at the external Al interfaces, which alters the local spatial blend composition within the interior of the film. The implications are that the dynamics of miscible thin film blends are dictated in part by component Tg differences, disparities in component relaxation rates, component-substrate interactions, and chain lengths (entropy of mixing).},
doi = {10.1021/acs.macromol.7b02152},
journal = {Macromolecules},
number = 3,
volume = 51,
place = {United States},
year = {Thu Jan 18 00:00:00 EST 2018},
month = {Thu Jan 18 00:00:00 EST 2018}
}