Physical properties of ion beam treated electrospun poly(vinyl alcohol) nanofibers

We show that the mechanical properties of nano-sized electrospun poly(vinyl alcohol) fibers can be modified using broad-energy ion beam implantation. The elastic moduli were determined using atomic force microscopy multi-point mechanical bending tests on individual fibers before and after treatment. With a dose of 8.0 × 1015 ions/cm2 of nitrogen ion we observed 30% increases in fiber elastic modulus with a simultaneous fiber diameter reduction. Two additional doses of nitrogen ion as well as a 8.0 × 1015 ions/cm2 of helium ion treatment showed that this stiffness improvement effect was dependent on ion dosage and ion species. The surface morphological features of the fiber mat were shown to be unaltered due to the ion beam treatment. Key chemical modifications via nitrogen ion treatment were the introduction of the functional groups amine and amide. These groups are important in promoting cell compatibility on polymer surfaces.