Size exclusion chromatography data polymer

Number average molecular weight data from size exclusion chromatography for polymers A through E has been given previously... 

Norbornene-based and oxa-norbornene-based monomers bearing dendritic side chains, XXX and XXXI (Fig. 19), were synthesized and polymerized via ROMP with initiator 6 [83]. Based on size exclusion chromatography data, the polymerization shows hving-like character up to DP=70. H- and C-NMR-spectroscopy revealed 35% cis and 65% tram sequences. These polymers displayed enantiotropic nematic and smectic mesophases, except for DP=5. In contrast to other classes of SCLCPs, the dependence of the DP on the transition temperatirre of the polymer was very weak. Glass transition and isotropization temperatures became independent of molecular weight above a degree of polymerization of about 10. 

The correction for BB in SEC is still a matter of active research, and a state of the art review has recently been published." " At present, the authors are participating in an lUPAC project entitled Data Treatment in the Size Exclusion Chromatography of Polymers one of the project objectives is the evaluation and standardization of existing BB correction techniques. Thus, the present article can be considered a first contribution toward that aim. 

This work was carried out in the framework of Project 2003-023-2-G.Meira (lUPAC) Data Treatment in the Size Exclusion Chromatography of Polymers, http //www.iupa-c.org/projects/2003/2003-023-2-400.html. Also, we are grateful for the financial support received from the following Argentine institutions CONICET, Universidad Nacional del Litoral, and SECyT. 

A new direct method for using size exclusion chromatography (SEC) to evaluate polymer intrinsic viscosity [n] is discussed. Sample viscosity information is obtained by combining SEC elution curve data and calibration data using direct SEC-[n] calibration procedures without involving polymer molecular weight calculations. The practical utility, convenience and the expected precision of the proposed method are illustrated. 

HE FIELD OF SIZE EXCLUSION CHROMATOGRAPHY (SEC) remains a viable and lively area of polymer characterization. Over the past several years, there has been considerable research activity in the area of SEC detection and data analysis in order to obtain more comprehensive information concerning the composition and molecular architecture of complex polymer systems. 

Figure 26-15 Larger CdSe quantum dots are eluted before smaller quantum dots by 0.1 M trioctylphosphine in toluene at 1.0 mL/min in size exclusion chromatography on a 7.5 x 300 mm cross-linked polystyrene column of 100-nm pore size Polymer Labs PLgel 5 (im. Triangles are CdSe and squares are polystyrene calibration standards. The size of the CdSe core was measured with a transmission electron microscope and the length of 1-dodecanethiol endcaps (0.123 nm) was added to the radius. [Data from K. M. Krueger. A. M. Al-Somall, J. C. Falkner, and V. L. Colvin, "Characterization of Nanocrystalline CdSe by Size Exclusion Chromatography," Anal. Chem. 2005, 77,3511.]...

The use of multiple detectors with size-exclusion chromatography (SEC) can greatly increase the information content available from a typical SEC analysis. This multidetector approach permits more accurate measurement of polymer properties than conventional SEC. The additional information, however, is obtained at the expense of an increase in the complexity of the instrumentation and data handling. In particular, a number of concerns arise in data acquisition and processing that are not present in conventional SEC. Some of these difficulties are outlined, and possible solutions are discussed. 

A computer simulation of size-exclusion chromatography-viscom-etry-light scattering is described. Data for polymers with a Flory-Schulz molecular weight distribution (MWD) are simulated, and the features of the different detector signals are related to the molecular weight and polydispersity of the distribution. The results are compared with previously reported simulated results using a Wesslau MWD. 

J. W. Mays and N. Hadjichristidis, Polymer characterization nsrng dilnte solntion viscometry, in Modern Methods of Polymer Characterization (H. G. Barth and J. W. Mays, eds.), John Wiley Sons, New York, 1991, pp. 227-269. C.-Y. Kno, T. Provder, M. E. Koehler, and A. F. Kah, Use of a viscometric detector for size exclnsion chromatography, in Detection and Data Analysis in Size Exclusion Chromatography (T. Provder, ed.), American Chemical Society, Washington, DC, 1987, pp. 130-154. 

New electronics and improved computer data acquisition capabilities have permitted the development of SEC with on-line triple detection using LS, VISC, and re-fractometry. On-line triple detection is known as size-exclusion chromatography cubed (SEC ) with the three dimensions being defined by the three detectors [3]. The use of SEC eliminates the requirement for column calibration, unlike conventional and universal calibration, where a premium is put on control of variables such as flow rate, temperature, and column resolution. SEC can offer advantages in polymer production quality control as well as in research and development of new polymers. 

A complementary use of polymer viscometry is the indirect evaluation of the MWD of a polymer from dynamic viscosity measurements [28-30]. The methods used to correlate the MWD of polymers to rheological data are based on the previous determination of the polymer relaxation spectrum from linear oscillatory shear experiments [31, 32]. MWDs obtained from viscometric data analysis can help in the determination of the MWD curve from online measurements, or in cases where this curve cannot be easily determined from size exclusion chromatography (SEC) [30, 31]. 

MS is one of the newest methods developed for polymer analysis, and a variety of other methods are currently adopted as well, here referred to as "conventional" methods. In everyday practice, MS data are routinely compared and integrated with the results of other conventional techniques for polymer analysis. Furthermore, MS is often coupled to polymer separation methods such as Size Exclusion Chromatography (SEC) and Liquid Chromatography (LC). 

Polydispersity defines the spread of the components that make up a polymer. The narrowest distribution is, by definition, 1, and the closer a polymer is to this value, the more likely is it that MALDl can be used. Once the polydispersity approaches 2, it becomes difficult to obtain data and the samples should be fractionated using size exclusion chromatography and the fractions analyzed separately to obtain a correct representation of the overall makeup of the polymer. 

Morals L.C., Curvelo A.A.S., Zambon M.D., Thermoplastic starch-lignosulfonate blends. 1. Factorial planning as a tool for elucidating new data from high performance size-exclusion chromatography and mechanical tests, Carbohydr. Polym., 62,2005, 104-112. 

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