Overview/Checklist

Overview

In this Lesson we are going to begin learning about the various characterization methods that are commonly used to analyze polymers. What methods are useful to analyze the molar mass, the dispersity, the crystallinity, etc.? There are many properties of polymers that we learned about so far, and we have to figure out how to actually measure them! We will begin by getting a general overview of the broad categories of characterization methods and the types of properties they can be used to measure. From there, we will go more in depth on a few select characterization methods: differential scanning calorimetry, size exclusion chromatography, end group analysis, and osmometry.

Figure 11.01: Overview of characterization methods used to analyze polymers

Source: Lauren Zarzar

Figure 11.01 is an overview of some of the key polymer characterization approaches and the properties they are used to measure. Spectroscopy, such as UV-VIS, FTIR, NMR, Raman, and mass spectrometry are used primarily analyze the chemical composition and molecular structure of polymers. For example, we can confirm using these techniques that we in fact made the chemistry of polymer we intended, we can determine the tacticity, or we can figure out end group concentration. Light scattering and diffraction are used to determine the conformations of polymers in solution and crystal structure. To analyze the thermal transitions in polymers, such as the glass transition, melting temperature, or heat capacity, we can use differential scanning calorimetry (DSC). Dilatometry also can provide insight into thermal transitions by measuring changes in free volume. Size exclusion chromatography (SEC) is an important tool that can tell us about the molar mass distributions of polymers. Osmometry and end group analysis are techniques that help us count the “number” of molecules in solution, which yields insight as to the number average molar mass. Osmometry can also be used to measure the Flory-Huggins interaction parameter. Of these techniques, we will not be covering spectroscopy or light scattering or diffraction in much more depth. The others we will discuss how the technique works, what it measures and how, and what are the advantages and limitations of the various approaches.

Learning Outcomes

By the end of this lesson, you should be able to:

• List the polymer characteristics that that can be analyzed using:
  • osmometry
  • end group analysis
  • size exclusion chromatography
  • differential scanning calorimetry
• Analyze results from:
  • osmometry
  • end group analysis
  • size exclusion chromatography
  • differential scanning calorimetry

Lesson Checklist

Please refer to the Canvas Calendar for specific timeframes.

Questions?

If you have questions, please feel free to post them to the General Questions and Discussion forum. While you are there, feel free to post your own responses if you, too, are able to help a classmate.