Ion beam processing of polymers as biomaterial

Our workers have studied the interaction of MeV ion in its track with large number of polymer types in order to tailor their properties for aerospace applications, and medical applications, control cell adhesion, improved surface properties of polymers used for heart-valve, for hip-joint implants, for fabrication of nano-pours used for DNA-sequencing and for filtration, as well as change in the surface properties of bio-compatible polymers for control drug/medication delivery. Chemical changes are produced in plastics by the ionizing radiation interacting with the polymer material resulting in the liberation of electrons from the atoms of the polymers. Radiation induces modifying processes in the polymer chains that produce chemical changes in the materials' properties. These processes can occur separately or in combination with one another and, depending on the nature of the material, one or more can occur simultaneously. Molecular excitations may be transmitted through the material as phonons or excitons which may cause bonds to break and produce scission, and cross-linking of the polymer chains. In many cases, dissociated hydrogen atoms and other small molecules move through the material and diffuse out as volatile species are formed. Dehydrogenation or the liberation of hydrogen atoms produces dangling bonds which eventually saturate and results in cross-linking. Other molecular emission processes, double bond formation, triple bond formation, dipole formation and precipitate formation by self clustering of the injected species can also occur. Our studies have revealed the effects on the polymers by radiation using energetic ion beams and have allowed us to modify the polymers as a result. This is a review paper of this work at the Center for Irradiation of Materials of AAMU and resulting applications