skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Impact of solvent quality on the density profiles of looped triblock copolymer brushes by neutron reflectivity measurements

Abstract

Preferential adsorption of poly(2-vinylpyridine)-deuterated polystyrene-poly(2-vinylpyridine) (PVP-dPS-PVP) triblock copolymers from toluene onto silicon leads to the formation of dPS loops tethered by the PVP end blocks. Using neutron reflectometry, we have determined the segment density profiles of these looped polymer brushes in toluene, a good solvent for the dPS block, and in cyclohexane at 20 C (poor solvent), 32 C, (near- solvent), and 50 C (marginal solvent). While the swelling behavior qualitatively agrees with that observed for singly grafted brushes, there are interesting differences in the local structural details: In a good solvent, the segment density profiles are composed of an inner parabolic region and a long, extended tail. In cyclohexane, the profiles are described by exponential decays. We ascribe these features to a novel polydispersity effect that arises due to tethering the PS loops by both ends. The results also show that the less dense layers undergo more significant changes in swollen height as solvent quality is changed and that the looped brushes of different molecular weight, asymmetry, and tethering density adhere to scaling relationships derived for lightly cross-linked polymer gels.

Authors:
 [1];  [2];  [3];  [3];  [4];  [3];  [3];  [3]
  1. University of Tennessee, Knoxville (UTK)
  2. Clemson University
  3. ORNL
  4. University of Utah
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1039250
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 41; Journal Issue: 5; Journal ID: ISSN 0024-9297
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ADSORPTION; ASYMMETRY; COPOLYMERS; CYCLOHEXANE; MOLECULAR WEIGHT; NEUTRONS; POLYMERS; REFLECTIVITY; SILICON; SOLVENTS; SWELLING; TOLUENE

Citation Formats

Huang, Zhenyu, Alonzo, Jose, Liu, Ming, Ji, Haining, Yin, Fang, Smith, Grant, Mays, Jimmy, Kilbey, II, S Michael, and Dadmun, Mark D. Impact of solvent quality on the density profiles of looped triblock copolymer brushes by neutron reflectivity measurements. United States: N. p., 2008. Web. doi:10.1021/ma702179x.
Huang, Zhenyu, Alonzo, Jose, Liu, Ming, Ji, Haining, Yin, Fang, Smith, Grant, Mays, Jimmy, Kilbey, II, S Michael, & Dadmun, Mark D. Impact of solvent quality on the density profiles of looped triblock copolymer brushes by neutron reflectivity measurements. United States. doi:10.1021/ma702179x.
Huang, Zhenyu, Alonzo, Jose, Liu, Ming, Ji, Haining, Yin, Fang, Smith, Grant, Mays, Jimmy, Kilbey, II, S Michael, and Dadmun, Mark D. Tue . "Impact of solvent quality on the density profiles of looped triblock copolymer brushes by neutron reflectivity measurements". United States. doi:10.1021/ma702179x.
@article{osti_1039250,
title = {Impact of solvent quality on the density profiles of looped triblock copolymer brushes by neutron reflectivity measurements},
author = {Huang, Zhenyu and Alonzo, Jose and Liu, Ming and Ji, Haining and Yin, Fang and Smith, Grant and Mays, Jimmy and Kilbey, II, S Michael and Dadmun, Mark D},
abstractNote = {Preferential adsorption of poly(2-vinylpyridine)-deuterated polystyrene-poly(2-vinylpyridine) (PVP-dPS-PVP) triblock copolymers from toluene onto silicon leads to the formation of dPS loops tethered by the PVP end blocks. Using neutron reflectometry, we have determined the segment density profiles of these looped polymer brushes in toluene, a good solvent for the dPS block, and in cyclohexane at 20 C (poor solvent), 32 C, (near- solvent), and 50 C (marginal solvent). While the swelling behavior qualitatively agrees with that observed for singly grafted brushes, there are interesting differences in the local structural details: In a good solvent, the segment density profiles are composed of an inner parabolic region and a long, extended tail. In cyclohexane, the profiles are described by exponential decays. We ascribe these features to a novel polydispersity effect that arises due to tethering the PS loops by both ends. The results also show that the less dense layers undergo more significant changes in swollen height as solvent quality is changed and that the looped brushes of different molecular weight, asymmetry, and tethering density adhere to scaling relationships derived for lightly cross-linked polymer gels.},
doi = {10.1021/ma702179x},
journal = {Macromolecules},
issn = {0024-9297},
number = 5,
volume = 41,
place = {United States},
year = {2008},
month = {1}
}