A Neutron Reflectivity Investigation of Surface and Interface Segregation of Polymer Functional End Groups

J. F. Elman, B. D. Johs, Timothy Edward Long, J. T. Koberstein

Research output: Contribution to journalArticle

155 Citations (Scopus)

Abstract

The distribution of polymer terminal groups at surfaces and interfaces is assessed by neutron reflectometry (NR) experiments on end-functional polystyrenes. Mono-terminated polystyrenes (PS) are synthesized anionically to include a short perdeuteriostyrene sequence adjacent to the end groups for the purpose of selective contrast labeling of the end groups for NR. The location of deuterium serves as a marker to indicate the location of the adjacent end group. Three cases of end group surface segregation are examined: a “neutral” control specimen prepared by proton termination, a “repulsive” end group system terminated with high surface energy carboxylic acid end groups, and an “attractive” end group system containing low surface energy fluorocarbon chain ends. All three systems exhibit damped oscillatory end group concentration depth profiles at both the air and substrate interfaces. The periods of these oscillations correspond approximately to the polymer chain dimensions. The surface structure of the “control” sample is dominated by the sec-butyl initiator fragment located at one end of the chain. This end group has a lower surface energy than that of the PS backbone and segregates preferentially to both the air and substrate interfaces. In the fluorosilaneterminated material, the low energy fluorinated end groups are depleted from the substrate interface but are found in excess at the air interface. In the carboxy-terminated material, the high energy carboxyl end group segregates preferentially to the silicon oxide overlayer on the substrate and is depleted at the air surface. X-ray photoelectron spectroscopy (XPS) is utilized surface compositions for the three systems.

Original languageEnglish
Pages (from-to)5341-5349
Number of pages9
JournalMacromolecules
Volume27
Issue number19
DOIs
Publication statusPublished - 1994 Sep 1
Externally publishedYes

Fingerprint

Functional polymers
Neutrons
Polystyrenes
Interfacial energy
Substrates
Air
Surface structure
Polymers
Fluorocarbons
Surface segregation
Deuterium
Silicon oxides
Carboxylic Acids
Carboxylic acids
Labeling
Protons
X ray photoelectron spectroscopy
Experiments

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

A Neutron Reflectivity Investigation of Surface and Interface Segregation of Polymer Functional End Groups. / Elman, J. F.; Johs, B. D.; Long, Timothy Edward; Koberstein, J. T.

In: Macromolecules, Vol. 27, No. 19, 01.09.1994, p. 5341-5349.

Research output: Contribution to journalArticle

Elman, J. F. ; Johs, B. D. ; Long, Timothy Edward ; Koberstein, J. T. / A Neutron Reflectivity Investigation of Surface and Interface Segregation of Polymer Functional End Groups. In: Macromolecules. 1994 ; Vol. 27, No. 19. pp. 5341-5349.
@article{9a084e3861154181ab2b633958bd69be,
title = "A Neutron Reflectivity Investigation of Surface and Interface Segregation of Polymer Functional End Groups",
abstract = "The distribution of polymer terminal groups at surfaces and interfaces is assessed by neutron reflectometry (NR) experiments on end-functional polystyrenes. Mono-terminated polystyrenes (PS) are synthesized anionically to include a short perdeuteriostyrene sequence adjacent to the end groups for the purpose of selective contrast labeling of the end groups for NR. The location of deuterium serves as a marker to indicate the location of the adjacent end group. Three cases of end group surface segregation are examined: a “neutral” control specimen prepared by proton termination, a “repulsive” end group system terminated with high surface energy carboxylic acid end groups, and an “attractive” end group system containing low surface energy fluorocarbon chain ends. All three systems exhibit damped oscillatory end group concentration depth profiles at both the air and substrate interfaces. The periods of these oscillations correspond approximately to the polymer chain dimensions. The surface structure of the “control” sample is dominated by the sec-butyl initiator fragment located at one end of the chain. This end group has a lower surface energy than that of the PS backbone and segregates preferentially to both the air and substrate interfaces. In the fluorosilaneterminated material, the low energy fluorinated end groups are depleted from the substrate interface but are found in excess at the air interface. In the carboxy-terminated material, the high energy carboxyl end group segregates preferentially to the silicon oxide overlayer on the substrate and is depleted at the air surface. X-ray photoelectron spectroscopy (XPS) is utilized surface compositions for the three systems.",
author = "Elman, {J. F.} and Johs, {B. D.} and Long, {Timothy Edward} and Koberstein, {J. T.}",
year = "1994",
month = "9",
day = "1",
doi = "10.1021/ma00097a013",
language = "English",
volume = "27",
pages = "5341--5349",
journal = "Macromolecules",
issn = "0024-9297",
publisher = "American Chemical Society",
number = "19",

}

TY - JOUR

T1 - A Neutron Reflectivity Investigation of Surface and Interface Segregation of Polymer Functional End Groups

AU - Elman, J. F.

AU - Johs, B. D.

AU - Long, Timothy Edward

AU - Koberstein, J. T.

PY - 1994/9/1

Y1 - 1994/9/1

N2 - The distribution of polymer terminal groups at surfaces and interfaces is assessed by neutron reflectometry (NR) experiments on end-functional polystyrenes. Mono-terminated polystyrenes (PS) are synthesized anionically to include a short perdeuteriostyrene sequence adjacent to the end groups for the purpose of selective contrast labeling of the end groups for NR. The location of deuterium serves as a marker to indicate the location of the adjacent end group. Three cases of end group surface segregation are examined: a “neutral” control specimen prepared by proton termination, a “repulsive” end group system terminated with high surface energy carboxylic acid end groups, and an “attractive” end group system containing low surface energy fluorocarbon chain ends. All three systems exhibit damped oscillatory end group concentration depth profiles at both the air and substrate interfaces. The periods of these oscillations correspond approximately to the polymer chain dimensions. The surface structure of the “control” sample is dominated by the sec-butyl initiator fragment located at one end of the chain. This end group has a lower surface energy than that of the PS backbone and segregates preferentially to both the air and substrate interfaces. In the fluorosilaneterminated material, the low energy fluorinated end groups are depleted from the substrate interface but are found in excess at the air interface. In the carboxy-terminated material, the high energy carboxyl end group segregates preferentially to the silicon oxide overlayer on the substrate and is depleted at the air surface. X-ray photoelectron spectroscopy (XPS) is utilized surface compositions for the three systems.

AB - The distribution of polymer terminal groups at surfaces and interfaces is assessed by neutron reflectometry (NR) experiments on end-functional polystyrenes. Mono-terminated polystyrenes (PS) are synthesized anionically to include a short perdeuteriostyrene sequence adjacent to the end groups for the purpose of selective contrast labeling of the end groups for NR. The location of deuterium serves as a marker to indicate the location of the adjacent end group. Three cases of end group surface segregation are examined: a “neutral” control specimen prepared by proton termination, a “repulsive” end group system terminated with high surface energy carboxylic acid end groups, and an “attractive” end group system containing low surface energy fluorocarbon chain ends. All three systems exhibit damped oscillatory end group concentration depth profiles at both the air and substrate interfaces. The periods of these oscillations correspond approximately to the polymer chain dimensions. The surface structure of the “control” sample is dominated by the sec-butyl initiator fragment located at one end of the chain. This end group has a lower surface energy than that of the PS backbone and segregates preferentially to both the air and substrate interfaces. In the fluorosilaneterminated material, the low energy fluorinated end groups are depleted from the substrate interface but are found in excess at the air interface. In the carboxy-terminated material, the high energy carboxyl end group segregates preferentially to the silicon oxide overlayer on the substrate and is depleted at the air surface. X-ray photoelectron spectroscopy (XPS) is utilized surface compositions for the three systems.

UR - http://www.scopus.com/inward/record.url?scp=0028499085&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028499085&partnerID=8YFLogxK

U2 - 10.1021/ma00097a013

DO - 10.1021/ma00097a013

M3 - Article

AN - SCOPUS:0028499085

VL - 27

SP - 5341

EP - 5349

JO - Macromolecules

JF - Macromolecules

SN - 0024-9297

IS - 19

ER -