RADIOISOTOPES

Radiation chemical processes has established a presence in polymerica materials processing due to their advantageous fabrication capability with uniform chemical reactions induced, size-controllability, etc. Meanwhile, there is a long history of the concept and technology of controlling the shape of polymer materials in nanometer scales. Pioneering works were reported in the middle of the 20th century, where the change of physical properties induced by radiation-induced chemical reactions was studied based on the molecular size and shape of polymers.

“Long chains” in polymers that can variously change their conformations dominantly determine the characteristics and advantages of polymer materials such as mechanical property, thermal stability, solubility and processability, and so on. Therefore, their statistical and quantitative analyses of polymer chains have been demonstrated. Since the radius of gyration for a polymer chain is in the range of several nanometers, it has been a more suitable target than a small molecule to characterize its conformation and size. Due to such nanometer-scale sizes, controlling the morphology and functions is directly linked to the development of functional nanomaterials. On the other hand, it is easy to imagine the difficulty in fabricating polymers into nanomaterials with a size of several to tens of nanometers. In this article, a part of our studies on the novel nano-fabrication techniques is introduced, utilizing polymerization, degradation, and cross-linking reactions induced by irradiations.