Solvent Effects on the Ultraviolet Absorption of Polystyrene
V M Story1, D McIntyre1, J H O'Mara1
1Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Summary
Polystyrene 705 exhibits hypochromism in specific solvents, deviating from Beer's law. This behavior is linked to light scattering and solvent activity, impacting extinction coefficients.
Area of Science:
- Polymer Science
- Spectroscopy
- Physical Chemistry
Background:
- NBS Standard Sample Polystyrene 705 is a widely used polymer standard.
- Understanding its spectral properties is crucial for accurate quantitative analysis.
- Previous studies have not fully elucidated its solution behavior in various solvents.
Purpose of the Study:
- To investigate the UV-Vis absorption properties of Polystyrene 705.
- To compare its spectral behavior to a model compound, ethylbenzene.
- To understand the factors influencing Beer's law adherence and extinction coefficients.
Main Methods:
- UV-Vis spectroscopy was employed to measure absorbance.
- Experiments were conducted in multiple solvents, including cyclohexane and carbon tetrachloride.
- Concentration dependence of extinction coefficients was analyzed.
Main Results:
- Polystyrene 705 showed a significant hypochromism around 38,300 cm-1 in several solvents.
- Beer's law was not consistently obeyed for Polystyrene 705 solutions.
- Extinction coefficients were found to depend on concentration, light scattering, and solvent activity coefficients.
Conclusions:
- The observed hypochromism and Beer's law deviations are attributed to intermolecular interactions and light scattering effects.
- Specific extinction coefficients for Polystyrene 705 were determined in cyclohexane (20.89) and carbon tetrachloride (27.38).
- These findings are important for accurate spectrophotometric measurements of polystyrene.
Keywords:
Carbon tetrachloridecyclohexaneethylbenzeneextinction coefficientpolymerpolystyrenesolvent effectsultraviolet absorptionMore Related Videos
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