Document Type


Date of Degree Completion

Spring 2019

Degree Name

Master of Science (MS)



Committee Chair

Dion Rivera

Second Committee Member

JoAnn Peters

Third Committee Member

Yingbin Ge


Development of plastic materials which produce visible color change when exposed to different environments has recently attracted attention for many biomedical applications.1,2Many biomedical devices are packaged under high concentrations of carbon dioxide (CO2) which can lower the pH of the packaging environment. This is similar to the CO2 chemistry responsible for ocean acidification.3 Dye molecules that are sensitive to environmental changes in pH (known as pH indicators) can be encapsulated in plastics and produce a visible color change when a medical device is removed from the sterile CO2 environment. Plastics made from large molecules known as polyelectrolytes can form complexes which may serve as inexpensive and multipurpose mediums for encapsulation of pH sensitive indicators. This research aims to combine the properties of both pH indicators and polyelectrolyte complexes (PECs) to form a stable plastic which will contain indicators sensitive to CO2 environments and slowly change color over extended periods of time, increasing the durability and usefulness in many such biomedical applications. Characterization of the physical properties of indicator containing polyelectrolyte complexes (ICPECs) was performed via scanning electron microscopy (SEM) in order to determine properties such as pore size. Compositional analysis of the ICPEC was performed via attenuated total reflection infrared spectroscopy (ATR-FTIR) and simultaneous thermal analysis (STA). It was shown that ICPECs are very dependent on both internal ionic concentration and moisture content and that these factors can significantly influence the rate at which ICPECs respond to introduction to high concentration CO2 environments such as are found in many biomedical applications.



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