Radical polymerization initiated from a solid substrate. 1. Theoretical background

From a survey of the literature on grafting free radical polymerization fro m solid surfaces we suggest kinetic schemes for the process. The system of differential equations in partial derivatives including the diffusion equat ion based on the classical theory of free radical polymerization and the as sumption that surface-bonded free radicals terminate by (1) reactions with bulk free radicals and (2) chain transfer to solvent or monomer are introdu ced. Computer simulations performed using the equations have shown good agr eement with the characteristic features of the grafting process; The rate o f grafting is Linearly proportional to the surface concentration of the ini tiator and decreases as the initiation rate in the bulk increases. It follo ws from the concentration profiles of the bulk free radicals that free radi cal concentration in the vicinity of the surface can be several times large r than that in the bulk. The concentration profile depends on the distance between two surfaces. For distances less than a critical distance of about 2 mu m, the concentration profile of the bulk free radicals is homogeneous.