Institute of Physics
Topic
Effect of high pressures on the free volume properties of crosslinked polymers studied by positron annihilation
PhD. program
Nuclear Chemistry and Radioecology
Year of admission
2025
Name of the supervisor
RNDr. Ondrej Šauša, CSc.
Contact:
Receiving school
Faculty of Natural Sciences
Annotation
The free volume properties of polymer networks of selected model materials from the methacrylate and epoxide groups, which will be prepared by polymerization at high pressures, will be investigated. The local free volume will be studied by using a positronium probe and measuring its lifetime at the annihilation site by positron annihilation lifetime spectroscopy (PALS) technique. The positron source will be the radioisotope 22Na. Based on the data experimentally obtained by the PALS technique and appropriate models for the conversion of orthopositronium lifetimes to the size of free-volume cavities, the properties of the created network (thermal expansion coefficients, glass transition temperature Tg, sub-Tg transitions, spatial homogeneity of the network) will be characterized. Changes in crosslinking, compared to classically prepared materials under laboratory conditions, and improved material properties are expected. The degree of double bond conversion by near infrared spectroscopy (NIR) and surface structure by scanning electron microscopy (SEM) will also be monitored. These polymers and their composites have versatile applications in various fields of science and technology (dental materials, 3D printing materials, protective coatings, lightweight construction materials or adhesives).