Abstract

Ionic liquids, substances that are liquid below 100°C with no discernible vapor pressure, have become popular in recent years for their ability to be “designer” solvents due to the endless cation and anion combinations that are possible. Phosphonium ionic liquids (PILs) are known to have high thermal stabilities which lend themselves to applications such as lubricants and thermal transfer fluids. This thesis investigated a novel tetraaryl phosphonium cation (dubbed [Mopyphos]+) and two substituted methyl derivatives to determine if substituted PILs were less thermally stable than non-substituted PILs and if the position of the methyl group affected long-term thermal stability. All three novel tetraaryl PILs were combined with the bis(trifluoromethylsulfonyl)imide (Tf2N−) anion, and short-term analysis indicated that these PILs are extremely thermally stable above 300°C, which compared favorably to existing ionic liquids. This work extends the thermal analysis to look at long-term stability via measuring the rate of mass loss as a function of temperature. The results provide a value that represents the temperature at which 1% of the PIL has been degraded after ten hours (T0.01/10hr). T0.01/10hr values for PILs are lower than short-term decomposition temperatures by 50-100°C, depending on the desired timeframe. This analysis also indicates that the 4-methyl and 6-methyl derivatives were less long-term thermally stable than [Mopyphos]Tf2N and that the position of the methyl group affected the long-term thermal stability.

Semester/Year of Award

Spring 2025

Mentor

Benjamin F. Wicker

Mentor Department Affiliation

Chemistry

Access Options

Open Access Thesis

Degree Name

Honors Scholars

Degree Level

Bachelors

Department

Chemistry

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