Radiation-Induced Modifications in Materials and Nanomaterials

Mircea Chipara
Indiana University

The energy deposited within materials by ionizing radiation triggers complex modifications of their physical and chemical properties. The talk focuses on radiation-induced modifications on polymers and composite materials obtained by dispersing nanoparticles with different functionalities within polymeric matrices. This choice is justified by the renewed interest in such materials as well as by their outstanding properties. Block copolymers, and eventually polymer blends, offer a cheap and large scale solution to nanostructured materials due to their self-assembly capabilities at nanometer scale. New nanocomposite materials, with improved properties, multifunctional features, smart capabilities, and/or self-healing capacity have already been obtained. Radiation-induced modifications in polymers open a window towards a better understanding of the effect of ionizing radiation on biomolecules.
    The first part of the talk collects some of the most relevant results obtained from the study of the effect of ionizing radiation (gamma, electrons, and accelerated ions starting from protons to uranium) on polymeric materials. The inhomogeneous degradation of polymers subjected to ionizing radiation, the effect of phase transitions on the time-temperature evolution of the physical properties of irradiated polymers, and dose-rate effects will be concisely analyzed.  
    The second part of the talk focuses on radiation-induced modifications in materials at nanometer scale and on radiation-induced modifications in nanomaterials. The need for a nanodosimetry theory will be critically reviewed.
The talk concludes with a brief discussion on potential applications derived from a better understanding of the effect of ionizing radiation on materials/nanomaterials as well as on some applications of the materials obtained or modified using ionizing radiation.  New research projects aiming at improved or new materials for space applications (where the radiation component of the space environment has an important contribution to the overall in space lifetime), for nuclear plants and radiation safety, and for radiation detection are sketched.