Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Surface Chemical Conversion of 3-glycidoxypropyldimethylethoxysilane on Hydroxylated Silicon
Surfaces: Contact Angle, FT-IR and Ellipsometry
Serkan Demirci, 1* Tuncer Çaykara 2
1 Department of Chemistry, Ahi Evran University, Kırşehir 40200, Turkey
2 Department of Chemistry, Gazi University, Ankara 06500, Turkey
Abstract — The chemical conversion of the top surface of 3-glycidoxypropyl dimethylethoxysilane (GPDMES) selfassembled
monolayer on hyroxylated silicon surface has been studied as a function of reaction time. A multiple-step procedure
was applied in this study. At first, GPDMES molecules were self-assembled on the hydroxylated silicon surface. The second
step is the modification of epoxy groups with 3,3’-iminodipropionitrile (IDPN) and the last step is the amidoximation reaction
of nitrile groups. Existence of the GPDMES, GPDMES-CN and GPDMES-(NH 2 )C=NOH layers covalently attached to silicon
surfaces were revealed by X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectroscopy (FT-IR).
Modification and conversion of surfaces were followed by contact angle, FT-IR and ellipsometry analysis.
The self-assembled monolayers (SAMs) of organosilanes
have been successfully used to tailor material surfaces to
obtain control over the molecular composition and the
resulting integral properties of the surfaces [1]. Several SAMs
systems have been explored and reviewed [2]. There is a
growing interest in covalently attached functional-terminated
monolayers. However, alkoxysilane monolayers terminated
with functional group cannot be directly prepared from
functional-alkoxysilane due to the reactivity of functional
groups with hydroxylated silicon, which competes with the
preferred reaction alkoxysilane groups and the substrate [3].
As a consequence, the chemical diversity of these monolayers
have been limited, especially when compared with SAMs on
solid surfaces.
SAMs have been analyzed by a variety of techniques
including spectroscopic [4], electrochemical, microscopic [5]
and wetting (contact angle) measurements [6]. Due to the high
sensitivity and simplicity of operation, contact angle
measurements have been widely used to study carboxylic acid
monolayers on gold, such as to monitor the formation process,
and to follow the step-by-step modification. FT-IR
spectroscopy has been proved to be a powerful tool to study
the chain conformation and orientation [7], to determine the
coverage and parking, and to monitor the surface chemistry
[8] of organic SAMs formed on different surfaces. As
mentioned before, FT-IR spectroscopy has been frequently
used for the characterization analysis of the original silicon
and modified silicon surfaces.
In this work, the use of three-step procedure for the
introduction of functional groups in SAMs on hydroxylated
surfaces is described. Reaction time has been studied and can
also be used to control product structure. This procedure is a
useful route to covalently attached monolayers with a variety
of controllable structure. This comprehensive report describes
our XPS, FT-IR, ellipsometry analysis and contact angle
studies of the surfaces. We report detailed ellipsometry
analysis, contact angle and FT-IR studies of GPDMES,
GPDMES-CN and GPDMES-(NH 2 )C=NOH surfaces as a
reaction time.
In this study, a new route was developed for the
preparation of amidoxime-terminated silioxane monolayers
covalently attached to silicon wafer surfaces. GPDMES,
GPDMES-CN and GPDMES-(NH 2 )C=NOH layer covalently
attached to silicon surface was characterized by XPS, FT-IR,
ellipsometry and contact angle measurements. Modification
and conversion of surfaces were followed by contact angle,
FT-IR and ellipsometry analysis. All the experimental results
show that direct control over the density of the –CN or
amidoxime groups on the surface can be obtained with
reaction time.
Figure: A model that explains GPDMES-CN or GPDMES-
(NH 2)C=NOH layers coverage on GPDMES or GPDMES-CN surface as
a function of reaction time.
* sdemirci@ahievran.edu.tr
[1] A. Shida, et al., Surf. Coat. Tech. 169-170, 686 (2003).
[2] A. Ulman, Chem. Rev. 96, 1533 (1996).
[3] S. Demirci, T. Caykara, Surf. Sci.,604, 649 (2010).
[4] L. Sun, R.M. Crooks, Langmuir 9, 1775 (1993)
[5] H.Y. Nie, et al., Thin Solid Films 517, 814 (2008).
[6] S.E. Creager, J. Clarke, Langmuir 10, 3675 (1994).
[7] A.B. Sieval, et al., Langmuir 17, 7554 (2001).
[8] S.S. Cheng, et al., Langmuir 11, 1190 (1985).
6th Nanoscience and Nanotechnology Conference, zmir, 2010 376