Influence of molecular rigidity on interfacial ordering in diphenyl-based polysiloxane films

Synchrotron X-ray reflectivity (XRR) shows significant differences between the ordering in thin films of diphenyl-based siloxane oligomers with single versus double backbones of –Si–O– repeating groups. We show that the more restricted conformational arrangement of twofold-skeleton molecules results...

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Bibliographic Details
Published in:Polymer (Guilford) 2007-11, Vol.48 (24), p.7163-7168
Main Authors: Evmenenko, Guennadi, Kewalramani, Sumit, Dutta, Pulak
Format: Article
Language:English
Subjects:
Applied sciences
BRAGG CURVE
CASTING
CHAINS
Exact sciences and technology
FLEXIBILITY
GEOMETRY
Inorganic and organomineral polymers
Interfacial ordering
MATERIALS SCIENCE
Molecular rigidity
national synchrotron light source
PARTICLE ACCELERATORS
Physicochemistry of polymers
Properties and characterization
REFLECTIVITY
SILOXANES
SOLVENTS
SUBSTRATES
SYNCHROTRONS
THIN FILMS
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Summary:Synchrotron X-ray reflectivity (XRR) shows significant differences between the ordering in thin films of diphenyl-based siloxane oligomers with single versus double backbones of –Si–O– repeating groups. We show that the more restricted conformational arrangement of twofold-skeleton molecules results in a higher degree of molecular ordering indicated by 2–2.5 times higher value of intensity of the corresponding Bragg peak in thin solid films of poly(phenylsilsesquioxane) than in films of poly(diphenylsiloxane), regardless of the solvent used for film casting. In both cases, the ordered molecules are located within 40–50Å of the substrate surface. The results indicate unambiguously that the chain stiffness of siloxanes governs the degree of ordering in the restricted geometry of the interfacial region.
ISSN:0032-3861
1873-2291
DOI:10.1016/j.polymer.2007.10.006