1 research outputs found
Temperature Activated Diffusion of Radicals through Ion Implanted Polymers
Plasma immersion ion implantation
(PIII) is a promising technique for immobilizing biomolecules on the
surface of polymers. Radicals generated in a subsurface layer by PIII
treatment diffuse throughout the substrate, forming covalent bonds
to molecules when they reach the surface. Understanding and controlling
the diffusion of radicals through this layer will enable efficient
optimization of this technique. We develop a model based on site to
site diffusion according to Fick’s second law with temperature
activation according to the Arrhenius relation. Using our model, the
Arrhenius exponential prefactor (for barrierless diffusion), <i>D</i><sub>0</sub>, and activation energy, <i>E</i><sub>A</sub>, for a radical to diffuse from one position to another
are found to be 3.11 × 10<sup>–17</sup> m<sup>2</sup> s<sup>–1</sup> and 0.31 eV, respectively. The model fits experimental
data with a high degree of accuracy and allows for accurate prediction
of radical diffusion to the surface. The model makes useful predictions
for the lifetime over which the surface is sufficiently active to
covalently immobilize biomolecules and it can be used to determine
radical fluence during biomolecule incubation for a range of storage
and incubation temperatures so facilitating selection of the most
appropriate parameters