Polymers containing less than 10 mol % of ions (ionomers) have been studied in depth for their potential in producing polymers with tailored properties for specific applications. A small molar percentage of ions can be incorporated into a polymer to drastically enhance the properties of the polymer. An ionomer that has been studied is that of isoprene copolymerized with sodium styrene sulfonate (poly(I-co-NaSS)). Research has been performed relating to the synthesis and chemical characterization of the copolymers. However, an in depth study of the way the physical properties are affected by a change in ion concentration has not been presented. Thus, it is the goal of this thesis to synthesize a series of poly(I-co-NaSS) copolymers with varying levels of sulfonated styrene and characterize their physical properties.
The poly(I-co-NaSS) polymers, containing a range of 1.15 to 4.74 mol % NaSS, were polymerized using free radical emulsion polymerization. The copolymer compositions were confirmed using combustion sulfur analysis. Dynamic light scattering indicated that large aggregates were present in solution. These aggregates were large enough that capillary intrinsic viscosities could not be measured. Small angle x-ray scattering (SAXS) and thermal analysis showed little change as the ion concentration was increased, while tensile, stress relaxation and adhesion properties were improved. The absence of changes in the SAXS patterns indicated that there was an absence of a well-defined ionic aggregate, while the mechanical properties showed evidence of electrostatic interactions. This can be at least partially attributed to ionic interactions on a smaller scale (doublets, triplets). / Master of Science / This research pertains to the creation of a series of polymers containing small amounts of ionic groups that allow tailoring the properties of the materials. The main component of the polymer is polyisoprene, which is also referred to as “natural rubber”. This material is elastic and can be used as a rubber (gloves) or can be manipulated to create a strong adhesive through addition of ionic groups.
The polymers were synthesized with varying levels of ionic groups, creating a series of six polymers. These polymers were tested for their chemical composition (the chemical make-up of the polymers), morphological properties (their phase structure and self-assembly of the polymers on a nanometer to micron scale), and their mechanical properties (the strength, elasticity, and adhesive properties of the polymer). It was determined that in terms of the morphology, the polymer remained mostly unchanged as the ion content was increased, but the mechanical properties improved dramatically. As the concentration of ionic groups increased, the strength of the polymer as well as the adhesive properties of the polymer, also increased. Understanding the structure-property relationships of these copolymers can allow researchers to tailor their structures to fit a desired application.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/86362 |
| Date | 20 June 2017 |
| Creators | Blosch, Sarah Elizabeth |
| Contributors | Macromolecular Science and Engineering, Turner, S. Richard, Moore, Robert Bowen, Orler, Edward Bruce, Riffle, Judy S. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf, application/vnd.openxmlformats-officedocument.wordprocessingml.document |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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