My current thesis is regarding the application of Gel Permeation Chromatography (GPC) equipment and principles to the study of polyelectrolyte configuration in solution. The main focus of this study is the effect of salt on the hydrodynamic volume/solution properties of polyelectrolytes and the ability of GPC to effectively determine the degree of variation. This involves the comparison of different salt types and concentrations in aqueous solution. The specific polyelectrolyte examined is poly (2-methacryloyloxyethyl phosphorylcholine) (PMPC), a zwitterionic polymer (i.e. one having both positive and negative charges on the monomer). PMPC is a fairly new and promising polyelectrolyte for use in protein drug delivery and biomaterial surface applications. Understanding the effects of salt on this polyelectrolyte will aid in the development of technologies involving this polymer as well as other zwitterionic polymers. Different salts were utilized to formulate an effect of salt ions so that a systematic analysis could be performed. Using a control as reference it was determined that the salt does have an effect on the solution properties of the polyelectrolytes, as expected. The specific
properties examined were characterized into two categories; solution properties and ion properties. Solution properties involved the investigation of salt concentration, solution ionic strength and solution pH effects. For ion properties, salts were selected on the basis of ion charge, charge type and ion size, so that the effects of both the cation and anion components could be analyzed. Two parameters, namely, ion size/type and ion valency were examined for both the cation and the anion. In addition the configuration of the anion was also investigated. vSpecific conclusions found in this study were as follows:
1) The salt concentration has an effect up to a certain "saturation" point.
2) The ionic strength has no visible effect (any effect is related to the concentration
component).
3) There is no observable solution pH effect.
4) There is no observable cation effect. This includes no cation type/size or cation
valency effect.
5) There is a significant anion effect.
6) A smaller anion has a greater effect than a larger anion.
7) A divalent anion has a greater effect than a monovalent anion.
8) A monatomic anion has a greater effect than a polyatomic anion.
It was found that the effect of ion properties is related to mechanisms associated with the geometry of the polyelectrolyte. The negative charge group of the polyelectrolyte which is situated closer to the backbone (inside) is less important to the change in hydrodynamic volume resulting from ionic interactions with the salts since it is shielded by the positive charge group situated at the end of the side chain (outside). The observed phenomena were also explained by other chemical and physical properties such as charge density and ionic potential. In addition to the original plan of study, other phenomena were observed and later explained, such as the presence of four distinct regions associated with salt concentration and the variation m the degree of hydrodynamic volume change with different molecular weight samples. The application of aqueous GPC equipment (including a differential refractive index detector (DRI)) and principles to the study of polyelectrolyte solution effects minimizes the detection equipment required and, provides sufficient resolution and accuracy for examination of solution properties while remaining time and cost effective. The project discoveries have shown that size exclusion chromatography provides an excellent means of obtaining a complete and accurate set of correlations between polyelectrolyte charge and salt effects. / Thesis / Master of Applied Science (MASc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23265 |
| Date | 06 1900 |
| Creators | Mahon, Jennifer |
| Contributors | Zhu, Shiping, Chemical Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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