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Investigation of the Effects of Isotopic Labeling at a PS/PMMA Interface Using SIMS and Mean-Field Theory
 

Summary: Investigation of the Effects of Isotopic Labeling at a PS/PMMA
Interface Using SIMS and Mean-Field Theory
Shane E. Harton, Frederick A. Stevie, and Harald Ade*,
Department of Materials Science & Engineering, North Carolina State UniVersity,
Raleigh, North Carolina 27695; Analytical Instrumentation Facility, North Carolina State UniVersity,
Raleigh, North Carolina 27695; and Department of Physics, North Carolina State UniVersity,
Raleigh, North Carolina 27695
ReceiVed October 14, 2005; ReVised Manuscript ReceiVed December 4, 2005
ABSTRACT: Isotopic labeling (deuteration) is known to affect the phase behavior of polystyrene (PS) and poly-
(methyl methacrylate) (PMMA) blends, but little is known regarding the changes in the interfacial properties at
the PS/PMMA interface due to deuteration of PS and/or PMMA. To investigate these potential changes, secondary
ion mass spectrometry (SIMS) was used to measure real-space depth profiles of dPS in hPS:dPS/hPMMA bilayers,
with the hPS:dPS blend being well within the single-phase region of the phase diagram. Profound changes in the
thermodynamic behavior of this system at the polymer/polymer interface are observed in the form of significant
segregation of dPS to the hPS:dPS/hPMMA interface. The observation of a depletion hole during the formation
of an equilibrium excess of dPS implies that the energetic gain at the interface per dPS chain has to be >kT.
These results cannot be described, even qualitatively, using previously reported changes in for PS/PMMA due
to isotopic labeling. The previously reported values of for dPS/hPMMA and hPS/hPMMA actually predict a
depletion of dPS at the hPS:dPS/hPMMA interface rather than the observed segregation. The observed interfacial
excess is quantified by generating theoretical profiles, using self-consistent mean-field theory (SCMF), and fitting

  

Source: Ade, Harald W.- Department of Physics, North Carolina State University

 

Collections: Physics