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Title: A Quantitative Study of Tethered Chains in Various Solution Conditions Using Langmuir Diblock Copolymer Monolayers

Abstract

This article summarizes our investigations of tethered chain systems using Langmuir monolayer of polydimethysiloxane-poly styrene (PDMS-PS) diblock copolymers on organic liquids. In this system, the PDMS block adsorbs to the air surface while the PS block dangles into the subphase liquid. The air surface can be made either repulsive or attractive for the tethered PS chain segments by choosing a subphase liquid which has a surface tension lower or greater than that of PS, respectively. The segment profile of the PS block is determined by neutron reflection as a function of the surface density, the molecular weights of the PS and PDMS blocks, and the solution conditions. We cover the range of reduced surface density (SIGMA) characteristic of the large body of data in the literature for systems of chains tethered onto solid surfaces from dilute solution in good or theta solvent conditions (SIGMA < 12). We emphasize quantitative comparisons with analytical profile forms and scaling predictions. We find that the strong-stretching limit invoked in analytical SCF and scaling theories is not valid over this Z range. On the other hand, over a large portion of this range (SIGMA < 5) tethered layers are well described by a renormalization groupmore » theory addressing weakly interacting or noninteracting chains. Simultaneous with the study of the profile form, the free energy of the chains is examined through the surface tension. A strong increase in the surface pressure is observed with increasing surface density which determines the maximum surface density which can be achieved. This apparently nonequilibrium effect is attributed to steric interactions and limited lateral interpenetration. This effect may explain several outstanding discrepancies regarding the adsorption of end-functionalized chains and diblock copolymers onto solid surfaces.« less

Authors:
Publication Date:
Research Org.:
Sandia National Labs., Albuquerque, NM (US); Sandia National Labs., Livermore, CA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
9719
Report Number(s):
SAND99-2100J
TRN: AH200125%%28
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Macromolecular Chemistry and Physics
Additional Journal Information:
Other Information: Submitted to Macromolecular Chemistry and Physics; PBD: 13 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ADSORPTION; COPOLYMERS; FREE ENERGY; GROUP THEORY; MOLECULAR WEIGHT; SOLVENTS; POLYSTYRENE; SURFACE TENSION; SILOXANES; MORPHOLOGY

Citation Formats

Kent, Michael S. A Quantitative Study of Tethered Chains in Various Solution Conditions Using Langmuir Diblock Copolymer Monolayers. United States: N. p., 1999. Web.
Kent, Michael S. A Quantitative Study of Tethered Chains in Various Solution Conditions Using Langmuir Diblock Copolymer Monolayers. United States.
Kent, Michael S. Fri . "A Quantitative Study of Tethered Chains in Various Solution Conditions Using Langmuir Diblock Copolymer Monolayers". United States. https://www.osti.gov/servlets/purl/9719.
@article{osti_9719,
title = {A Quantitative Study of Tethered Chains in Various Solution Conditions Using Langmuir Diblock Copolymer Monolayers},
author = {Kent, Michael S.},
abstractNote = {This article summarizes our investigations of tethered chain systems using Langmuir monolayer of polydimethysiloxane-poly styrene (PDMS-PS) diblock copolymers on organic liquids. In this system, the PDMS block adsorbs to the air surface while the PS block dangles into the subphase liquid. The air surface can be made either repulsive or attractive for the tethered PS chain segments by choosing a subphase liquid which has a surface tension lower or greater than that of PS, respectively. The segment profile of the PS block is determined by neutron reflection as a function of the surface density, the molecular weights of the PS and PDMS blocks, and the solution conditions. We cover the range of reduced surface density (SIGMA) characteristic of the large body of data in the literature for systems of chains tethered onto solid surfaces from dilute solution in good or theta solvent conditions (SIGMA < 12). We emphasize quantitative comparisons with analytical profile forms and scaling predictions. We find that the strong-stretching limit invoked in analytical SCF and scaling theories is not valid over this Z range. On the other hand, over a large portion of this range (SIGMA < 5) tethered layers are well described by a renormalization group theory addressing weakly interacting or noninteracting chains. Simultaneous with the study of the profile form, the free energy of the chains is examined through the surface tension. A strong increase in the surface pressure is observed with increasing surface density which determines the maximum surface density which can be achieved. This apparently nonequilibrium effect is attributed to steric interactions and limited lateral interpenetration. This effect may explain several outstanding discrepancies regarding the adsorption of end-functionalized chains and diblock copolymers onto solid surfaces.},
doi = {},
journal = {Macromolecular Chemistry and Physics},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {8}
}