X-ray Reflectivity Study of Ultrathin Liquid Films of Diphenylsiloxane−Dimethylsiloxane Copolymers

Using X-ray reflectivity, we observe drastic differences in the interfacial structure and molecular ordering of diphenylsiloxane−dimethylsiloxane copolymer thin films deposited on hydroxylated versus H-terminated (etched) silicon wafers. We find that substrate type and comonomer ratio determine the...

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Bibliographic Details
Published in:Langmuir 2006-07, Vol.22 (14), p.6245-6248
Main Authors: Evmenenko, Guennadi, Mo, Haiding, Kewalramani, Sumit, Dutta, Pulak
Format: Article
Language:English
Subjects:
Chemistry
COPOLYMERS
Exact sciences and technology
General and physical chemistry
INTERFACES
MATERIALS SCIENCE
MICROSTRUCTURE
MOLECULAR STRUCTURE
national synchrotron light source
SILICON
SILOXANES
SUBSTRATES
THIN FILMS
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Summary:Using X-ray reflectivity, we observe drastic differences in the interfacial structure and molecular ordering of diphenylsiloxane−dimethylsiloxane copolymer thin films deposited on hydroxylated versus H-terminated (etched) silicon wafers. We find that substrate type and comonomer ratio determine the conformational arrangements in these liquid films. High-energy bonding between the substrate and the molecules and an increase in rigidity of the molecules due to replacement of methyl groups by phenyl groups leads to a specific molecular ordering at the liquid/solid interface and pronounced density oscillations in this region. The observed structural reorganizations are explained by the interplay and the established balance between the chain flexibility and the polymer−substrate interactions.
ISSN:0743-7463
1520-5827
DOI:10.1021/la060522d