Abstract
Anionic polymers such as polyacrylic acid and alginates are used in dentistry for various purposes. This research investigated how properties of such systems can be modified and potentially improved by addition of clay nanofillers. Natural clay samples were used as well as different samples of the modified clay to achieve improved mechanical properties on materials such as glass ionomer cements (GICs) and hydrogels.Clay particles (montmorillonite (MMT) platelets, size < 1 μm) were treated with different length chains of ω-amino carboxylic acids (ω-aa): 12-aminododecanoic acid (ADA), 6-aminohexanoic acid (AHA) and γ-aminobutyric acid (GABA); there has been evidence that such amino acids help dispersion into polymer matrix. Different routes for treating the clay were investigated and the best results were obtained using elevated temperature and low pH.
The matrix of GICs consists of polymers such as polyacrylic acid (PAA) and such polymers interact well with clay. The addition of ω-aa modified clays was found to increase the compressive strength of the GICs by ~70 %.
Another major problem with dental materials was addressed, currently there is no available material that offers effective, lasting protection against bacterial colonisation. For this reason, the same clay (MMT) was treated with chlorhexidine (CHX) to create a system that would retain its antimicrobial properties, or even could serve as a slow release system depending on the amount of CHX added. CHX intercalated into MMT was found to be bound strongly with very slow or no release.
Additionally, a novel nanofiller system was proposed which could offer both enhanced strength and antimicrobial properties, by adding the modified clays described above into an alginate hydrogel structure. The Young’s modulus was determined by compressing gel beads; inclusion of clay particles resulted in an increase in modulus (between 33 and 69%) but the surface modification with ω-amino acids did not result in a significant difference.
| Date of Award | 25 Jan 2022 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Jeroen S Van Duijneveldt (Supervisor), Michele E Barbour (Supervisor) & Annela M Seddon (Supervisor) |