MULTI-POLYMERIC PARAMETERS EVALUATION OF FAST SOL-GEL PROCESS BY
TRIPLE-DETECTOR GEL PERMEATION CHROMATOGRAPHY
Raz Gvishi1, Ali Soleymannezhad2 &Wei Sen Wong2
1
Photonic materials group, Electro-Optics Division, Soreq Nuclear Research Center, Yavne 81800, Israel
rgvishi@Soreq.gov.il
2
Viscotek, 15600 West Hardly Rd., Houston, TX, USA 77060, www.Viscotek.com
Ali.Soleymannezhad@viscotek.com
The sol-gel method is a process for preparing silica-like materials at low temperatures (25°C – 80°C).
Recently we presented a novel fast sol-gel method to prepare crack-free sol-gel samples without
shrinkage which are promising materials for preparation of optical elements such as waveguides and
submicron structured replicas and can also be used as an optical bonding material1-3. In order to use the
fast sol-gel material (FSG) for specific applications there is a need for quality control of the
manufacturing method. In this work we present the use of Viscotek’s advanced multi-detector gel
permeation/size exclusion chromatography (GPC/SEC) system, TDAmax TM, to investigate various
molecular and solution properties of the fast sol-gel manufacturing process. Dynamic light scattering
(DLS) and GPC/SEC are commonly used methods for characterization of macromolecules4,5. DLS
characterizes the hydrodynamic size and particle distribution of the polymer chains in a given solvent,
while the multi-detector GPC/SEC provides more detailed information on molecular weight, molecular
weight distribution, molecular size and density, structure and conformation. In this work we have
developed a method for evaluation of the preparation manufacturing processes of fast sol-gel (FSG) in
situ. The evaluation includes parallel measurements of the refractive index, light scattering and solution
viscosity of the sample to determine molecular weight moments, molecular weight distribution,
hydrodynamic size and refractive index increment (dn/dc). Such multi-parameter evaluation
distinguishes between states of polymerization, different species of sol-gel (content and structure),
specifically, aggregate formation and degree of branching. Due to low refractive index increment of
silicone polymers, a Solvent Enhanced Light Scattering (SELSTM) technique was employed to obtain
optimum signal/noise for both light scattering and refractive index detectors. The advanced GPC/SEC
technique proposed in this project enabled the discovery of various types of FSG polymers. First, a
highly branched group with relatively low molecular weight values (about 2x104 g/mole) and smaller
particles size (around Rh=1.5 nm). Second, a highly branched group with higher molecular weights
(about 1.5x106 g/mole) and larger particles size (Rh=10 nm). And third, a low branched group with lower
molecular weight values (about 1.5x104 g/mole) and large particles size (Rh=15 nm).
References:
1. R. Gvishi, "Fast sol-gel from fabrication to applications" Journal of Sol-Gel science and Technology
Special Issue for the 60th Anniversary of Prof. David Avnir, in press September (2008).
2. R. Gvishi, G. Strum, N. Shitrit, R. Dror, "Optical waveguide fabrication using a fast sol-gel method",
Optical Materials, 30, 1755, (2008).
3. R. Gvishi, M. Pokrass, G. Strum, "Optical bonding with fast sol-gel", Journal of European Optical
Society, in press October 2008.
4. T. Matsunaga, M. Shibayama, Physical Review 76, 1, (2007).
5. J. Araki, K Ito, Polymer, 48, 7139, (2007).
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