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Evaluation of Industrial Methods of Size-Exclusion Chromatography (SEC) of Difficult-to-Dissolve Polymers

Title: The Evaluation of Industrial Methods of Size-Exclusion Chromatography (SEC) of Difficult-to-Dissolve Polymers.
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Name(s): McNeel, Kelsey, author
Chemistry
Type of Resource: text
Genre: Text
Issuance: serial
Date Issued: 2011
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: In experiments presented here, well-characterized polystyrene and poly(methyl methacrylate) standards were analyzed using size-exclusion chromatography and an approach in which the mobile phase differed from the solvent in which the polymer was dissolved. Solvent combinations included a mobile phase in which the polymer was insoluble and a mobile phase that was immiscible with the solvent. It is important to determine the accuracy of molar mass averages and distributions obtained from such experiments because the averages and distributions are frequently used in industry to give information about physical properties of the analyte. It is often expensive and time consuming to determine the ideal solvent in which to analyze a polymer, and even more so to purge the system of the previous solvent and condition it with the new one. To circumnavigate these problems, polymers are sometimes dissolved in a known solvent and injected into an instrument containing a chemically different mobile phase, a mobile phase that is already in the instrument. We found that performing experiments using this industrial approach needs to be done with caution. The molar mass averages and distributions can be determined accurately when the mobile phase is a solvent for the polymer and miscible with the solvent, but other cases were less conclusive. Using a mobile phase that is not a solvent for the polymer appears to yield accurate results for low molar mass polymers (<20,000 g/mol) but, in some solvent combinations, yields exclusively solvent peaks. It is likely that the larger polymers precipitate when the miscible solvent and mobile phase mix and the polymers are adsorbed onto the column. Experiment set 5, in which the mobile phase was a solvent for the polymer but was immiscible with the solvent in which the polymer was dissolved, yielded no peaks in these experiments. It is hypothesized that this lack of peaks is a result of enthalpic interactions between the stationary phase, sample solution, and mobile phase. It appears that the elution of the polymer may not be driven by entropic interactions, as is the case in a size-exclusion mechanism, resulting in the co-elution of the polymer and the solvent.
Identifier: FSU_migr_uhm-0026 (IID)
Keywords: Size-exclusion chromatography, Polymers
Submitted Note: A Thesis submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Honors in the Major.
Degree Awarded: Spring Semester, 2011.
Date of Defense: April 13, 2011.
Subject(s): Biochemistry
Chemistry
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_uhm-0026
Restrictions on Access: http://creativecommons.org/licenses/by-nc-nd/3.0/
Owner Institution: FSU
Is Part of Series: Honors Theses.

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McNeel, K. (2011). The Evaluation of Industrial Methods of Size-Exclusion Chromatography (SEC) of Difficult-to-Dissolve Polymers. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_uhm-0026