ISPAC 2013 Short Course, Sunday June 9, 2013
Course #1, 8:30-10:00am
Basics of Gel Permeation Chromatography, including multi-detectors.
Dr. John McConville, Polymer Standard Services, Amherst MA
An introduction to theoretical and practical aspects of GPC. Detailed discussion of GPC equipment (pumps, injection valves, detectors and other GPC instrumentation) will be presented. GPC columns, their performance characteristics and how to choose the right type and number of columns will be reviewed. The appropriate use of multiple detectors (refractive index, UV, viscometer, and multiple angle light scattering) will be reviewed and explained. Different methods for obtaining molecular weight distributions, beginning with traditional column calibration and proceeding through universal calibration and light scattering, which requires no calibration , will be covered. A brief overview of hyphenation in GPC (using FTIR, NMR and MS detectors) and 2-D techniques. Examples and applications including polyolefins, copolymers, aqueous polymers, etc. will be presented. Finally, an overview of common problems and troubleshooting will be given.
10:00-10:30 am Refreshment Pause
Course #2, 10:30am-noon
Advanced Liquid Chromatography, including 2D-LC and Hyphenated Methods (LC-NMR, LC-FTIR, LC-MS)
Prof. Harald Pasch, University of Stellenbosch, South Africa
Complex polymers are distributed in more than one direction of molecular heterogeneity. In addition to the molar mass distribution, they are frequently distributed with respect to chemical composition, functionality, and molecular architecture. For the characterization of the different types of molecular heterogeneity it is necessary to use a wide range of analytical techniques. Preferably, these techniques should be selective towards a specific type of heterogeneity. The combination of two selective analytical techniques is assumed to yield two-dimensional information on the molecular heterogeneity.
For the analysis of complex polymers different liquid chromatographic techniques have been developed, including size exclusion chromatography (SEC) separating with respect to hydrodynamic volume, and liquid adsorption chromatography (LAC) which is used to separate according to chemical composition. Liquid chromatography at the critical point of adsorption (LC-CC) has been shown to be a versatile method for the determination of the chemical heterogeneity of complex block and copolymers.
The present short course presents the principle ideas of combining different analytical techniques in multidimensional analysis schemes for complex polymers. Most promising protocols for hyphenated techniques refer to the combination of two different chromatographic methods and the combination of chromatography and spectroscopy. The basic principles of two-dimensional chromatography and the hyphenation of liquid chromatography with selective detectors such as 1H-NMR, FTIR and MS will be discussed.
Noon-1:30pm, lunch provided by ISPAC
Course #3, 1:30-3:00pm
Characterization and applications of several biopolymers
Professor Marguerite Rinaudo, Biomaterials applications, Grenoble, France
We will focus on water soluble polysaccharides; natural and modified polysaccharides will be considered to describe the main physical properties performed usually by polysaccharides in solution and gel states. Then, the main techniques used for their characterization will be discussed using several examples. Some applications will also be mentioned.
Systems considered: water soluble polysaccharides based on different types of monomeric units: anionic carboxylic uronic acid (as in pectins and alginates), glucosamine (as in chitosan) becoming cationic in acid medium, neutral sugar unit (glucose and galactose in galactomannans; methylated glucose in methylcellulose)
Polyelectrolyte behavior: Control of the purity of polymers and of the nature of counterion; Specific behavior of charged polymers in aqueous medium in viscometry and light scattering; Screening of long range electrostatic repulsions.
Prediction of the activity of mono and divalent counterions
Specific problems: Prevention of aggregation due to high yield of –OH monomeric units (H-bond network)
Stereoregularity, semi-rigid character and cooperativity of interactions
Polysaccharide investigated in this course:
Alginates (structure and gel characterization in acidic conditions and in presence of calcium; mechanism; application as biomaterial) (Main techniques: NMR, rheology)
Hyaluronan (conformation in solution, rheology in relation with molar mass and polymer concentration for viscosupplementation) (Main techniques: molecular modeling, NMR, SEC, rheology)
Chitosan (conformation in relation with the degree of acetylation; behaviour compared with that of hyaluronan; application as biomaterial). (Main techniques: molecular modeling, RMN, rheology, SEC)
Methylcellulose (example of amphiphilic system and mechanism of gel formation induced by temperature increase in relation with methyl substituents distribution along the cellulosic chain) (Main techniques: NMR, chromatography, DSC, rheology)
Introduction to Scattering-Based Polymer Characterization Methods
3:00-3:30pm Refreshment Pause
Course #4, 3:30-5:00pm
Introduction to Scattering-Based Polymer Characterization Methods
Paul S. Russo, Department of Chemistry and Macromolecular Studies Group Louisiana State University Baton Rouge, LA
Determination of macromolecular and supramolecular structure in solutions, gels and solids can be challenging because the materials are often too soft for microscopic visualization at high resolution. Even when microscopy yields images without artifact, it can be tedious to examine a sufficient number of specimens, especially in polydisperse systems. In these cases, scattering of visible or X-ray radiation, or of neutrons, can be used to obtain quantitative information without bias and usually without artifact. Absolute molecular weights, particle sizes, extent of aggregation, stability, and phase behavior are just some of the problems that can be studied. Often scattering methods are coupled to on-line chromatographic separations, so that effectively monodisperse samples can be examined. In this short course, the essentials will be presented. Subjects will include scattering geometries, the scattering vector, angular dependence, particle sizes, correlation length and intensity fluctuations in time. Applications from the literature will illustrate these principles. A brief discussion of available instrumentation will round out the discussion.