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Application Notes
Our database of GPC/SEC application notes explain the use of concentration, viscometer and light scattering detectors to obtain a distribution of absolute molecular weight, size and intrinsic viscosity, as well as information on conformation, aggregation, branching and copolymer composition.
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Theory Answers
How does separation work in Gel Permeation Chromatography?
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Featured Articles |
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Viscotek is proud to present a random selction of articles from renowned publications highlighting applications and success stories from customers using our products. Refresh page for more articles. |
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| University of Colorado Dental School Researcher uses Triple Detection with light scattering to characterize nanogels
“Controlled preparation of nanogel particles and their use as macromonomers”
|  Modern materials are used in denistry today. Bonding agents are important to repair teeth with proper mechanical properties for longer life of repairs. Another goal is to use visible light in place of UV in curing the bonding resin. This paper reports the research at the University of Colorado School of Dentistry. Small amounts of divinyl monomers in a polymerization usually results in insoluble macrogels. This work resulted in better control of functionality. Nanogel-modified dental resins were added to conventional dental resin in 10 to 50 percent concentrations and resulted in transparent colloidal dispersions. A GPC triple detection size-exclusion-chromatography system from Viscotek was used to determine molecular weights.
Polymer Preprints 2006, 47(2), 825
JW Stansbury, M Trujillo-Lemon, X Ding, and SM Newman
Department of Craniofacial Biology, University of Colorado School of Denistry, Aurora, CO 80010
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| Principles of triple detection GPC/SEC – Part 3: The Viscometer Detector
|  Gel Permeation Chromatography (GPC) is also known as Size Excludion Cromatography (SEC). It is a very common method for giving molecular weight (Mw) average and distribution for synthetic and natural polymers and proteins, but has progressed from the original relative Mw limitations. Triple Detection, using light scattering, concentration and viscometer detection has grown rapidly for the additional information it provides. The differential viscometer detector was invented by Haney and uses 4 capillary tubes, arranged in a balanced bridge configuration analogous to the Wheatstone bridge in electrical circuits. Earlier single-capillary viscometers lacked the pump-noise cancellation feature and was subject to viscosity fluctuations caused by temperature changes. The article explains the importance of the viscometer in providing intrinsic viscosity, hydrodynamic radius, branching information and the concept of Universal Calibration. Haney’s previous detector articles discussed the importance of light scattering (and specifically low angle light scattering) and the differential refractometer, and how all three detectors work together.
International Laboratory News June/July 2006
Max A. Haney
Viscotek, 15600 West Hardy, Houston, TX 77060
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| Synthesis of Soluble Branched Polyimides Derived from an ABB’ Monomer
|  This paper shows the power of the Mark-Houwink plot (molecular weight v. log intrinsic viscosity) to show the degree of branching in polymers. Aromatic polyimides (PI) are useful for excellent electrical, thermal, and high-temperature mechanical properties, however, they are difficult to process because of low solubility. Hyperbranched polymers have attracted considerable attention because of their branched structure, giving lower viscosity and higher solubility and large number of end groups for attaching other polymers. Most hyper-branched polymers derived from AB2 monomers result in weak films needed for engineering plastics. The authors polymerized an ABB’ monomer to produce a lower branched hyperbranched polymer to improve film strength. A Size exclusion chromatography system from Viscotek Corporation with triple detection and low angle light scattering was used for accurate molecular weight and intrinsic viscosity information. With low-angle light scattering, an absolute weight is determined directly, without extrapolation or corrections. Intrinsic viscosity (IV) is obtained from the four-capillary viscometer detector. IV values give inverse polymer density and will drop as branching increases. Molecular weight vs. IV provides a shape factor (alpha) from the slope of the Mark-Houwink equation ([IV] = KM^a) where K is a constant for a particular polymer and solvent and M (molecular weight). A linear polymer resulted in an alpha (slope) of 0.72 and the hyperbranched result was 0.3, showing a good method for prediction of film performance.
Journal of Polymer Science Part A Polymer Chemistry, Vol. 42, 3200-3211 (2004)
Kun-Li Wang,1 Mitsutoshi Jikei,2 Masa-Aki Kakimoto1
1Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Meguro-ku,Tokyo 152-8550, Japan
2Department of Material Process Engineering and Applied Chemistry for Environments, Akita University1-1 Tegata Gakuen-machi, Akita-shi, Akita, 010-8502, Japan
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| Viscotek SEC system used to quickly and accurately verify literature values
Characterization of Poly(epsilon-Caprolactone) via size exclusion chromatography with online right-angle laser-light scattering and viscometric detectors
|  The data reported in this paper is not new, but it shows that fundamental polymer data is generated quickly and accurately without laborious off-line fractionation, even when working with low-molecular weight polymers. A Viscotek light scattering and viscometer dual detector used with a differential refractometer was used to show Mark-Houwink-Sakurada (MHS) plots of poly(E-caprolactone (PCL) in tetrahydrofuran (THF). Along with the MHS, the radius of gyration (Rg) versus molecular weight was determined and both are used to obtain Flory’s Characteristic ratio Coo to give us chain flexibility data.The power law exponent v and prefactor K’ relating Rg and molecular weight M is plotted and the Burchard-Stockmayer-Fixman (BSF) equation provides reliable estimates of K-theta by plotting intrinsic viscosity times Mw vs Mw. Another plot uses Rg times Mw vs Mw to derive the Baumann plot to calculate an alternative method for Coo. The multi
detector SEC technique has been shown to yield estimates of Coo that are in accord with literature values.
International Journal of Polymer Analysis and Characterization 2003, vol 8, 383-394
Yi Huang1, Zhongde Xu1, Yiping Huang2, Dezhu Ma2, Jinchuan Yang3, Jimmy W Mays3
1East China University of Science and Technology, Dept of Polymer Science & Eng, Shanghai, China
2China University of Science and Technology, Dept Polymer Science & Engineering, Hefei, China
3University of Alabama at Birmingham, Dept of Chemistry, Birmingham, Alabama, USA
Address correspondence to Jimmy Mays, Dept Chemistry, Univ. Tennessee – jimmymays@utk.edu
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| Low Angle Light Scattering used for Accurate Molecular Weight in a Size Exclusion Chromatography System
Maltodextrins
|  Maltodextrins are used in the food and pharmaceutical fields, and are produced from the degradation of starch – often by the use of enzymes. Maltodextrins are often used to modify texture and viscosity. Because the starting material is starch, the resulting maltodextrins may have both linear and branched molecules, leading to large errors if characterized by conventional gel permeation chromatography (GPC). Triple detection GPC shows accurate molecular weight results plus molecular structure, including degree of branching. Samples from different sources show very large differences in branching and molecular weights.
LC/GC Application Notebook February 2004
Paul Clarke, Viscotek Corporation, Houston, Texas 77060
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