Abstract

Polymers exist in different thermodynamical states, such as the glassy or rubbery state, and undergo phase transitions at different temperatures. By exploring the rate at which a polymer's porosity changes as a function of temperature we are able to determine the temperatures at which polymers undergo phase transitions. Using Positron Annihilation Lifetime Spectroscopy (PALS), a well established technique for probing pore volume, we investigated three thiol-ene polymer networks with modified divinyl sulfone ends. Pore volume was measured at selected temperatures between -230 and 70 degrees Celsius, and all three samples exhibited both a beta transition, which signals side chain movement, and a glass transition, which indicates coordinated movements of polymer chains. The samples had beta transition values between -129 and -105 degrees Celsius, and glass transition values between 5 and 15 degrees Celsius.