Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Master of Engineering Science

Program

Chemical and Biochemical Engineering

Supervisor

Charpentier, Paul A.

2nd Supervisor

Rizkalla, Amin

Co-Supervisor

Abstract

Moisture inside the mouth adds challenge to making denture adhesives formulations. Some formulations have zinc to enhance adhesion on wet skin despite knowing the health hazards. Inspired by mussel foot proteins’ catechol unit’s strong underwater adhesion, nine catechol-containing copolymers (P1A-P3C) were synthesized by free radical polymerization of 3,4-dimethoxystyrene (3,4- DMS) with different styrene derivatives followed by deprotection. P1A-P3C were used to make Fn(P)-C-PBS denture adhesive formulations which had suitable shear stresses around ≥ 5 kPa satisfying ISO 10873. In-situ NMR studies of free radical polymerization of 3,4 - DMS and styrene derivatives allowed computation of their reactivity ratios showing all copolymers are random. This work has shown the potential of polystyrene-based catechol copolymers for next-generation denture adhesives.

Summary for Lay Audience

Dentures are commonly worn accessories by the elderly population upon losing their real teeth. In conjunction, denture adhesives under brand names Poligrip, Effergrip, and Fixodent, are applied to stabilize the denture fitting inside the oral mucosa. To function, the denture adhesive draws saliva to swell and generate a cushion between the denture and oral mucosa. This prevents food particles being entrapped in between. However, some formulations include zinc to better the adhesion properties despite knowing the health hazards it can present to the body. According to ISO 10873, a standard for all commercial denture adhesives, all formulations must be non-toxic, have shear stress of 5 kPa or higher, and prevents denture from displacing for 12-16 hours. To develop a denture adhesive that adheres effectively on wet surfaces, researchers have turned their attention to mussel foot proteins and drawn inspiration from their catechol chemistry.

In this work, nine polystyrene-based catechol copolymers were made by polymerizing 3,4-dimethoxystyrene (3,4-DMS) and different styrene building blocks. The resulting copolymers were then treated with tribromo boron to provide catechol units in the chain. Subsequently, the copolymers were used to make denture adhesive formulations which were evaluated by lap shear experiments. The shear stress values were around ≥ 5 kPa which satisfies ISO 10873. In addition to evaluating their potential as active ingredients, the polymerization of 3,4 – DMS and styrene building blocks were studied under in-situ NMR. Doing so provides insight into the chain sequence of the copolymer as structure dictates both chemical and physical properties. From the in-situ NMR studies, all copolymers have a random sequence. This work has shown the potential of polystyrene-based catechol copolymers for next-generation denture adhesives.

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