“Grafting through” Polymerization

We use a combination of computer simulation and experiments to comprehend “grafting through” polymerization, i.e., copolymerization of free monomers in solution and polymerizable units bound chemically to a substrate. Free polymer chains are formed initially in bulk solution and if they incorporate at least one surface-bound monomer, the macromolecules get covalently bonded to the surface during the polymerization process. We concentrate specifically on addressing the effect of spatial density of the surface-bound monomers on the formation of the surface-attached polymers. We employ a lattice-based Monte Carlo model based on the bond fluctuation model scheme to provide molecular-level insight into the grafting process. For experimental validation, we create gradients of density of bound methacrylate units on flat silicon wafers using organosilane chemistry and carry out “grafting through” free radical polymerization initiated in bulk. The proximity of the surface-bound polymerizable units promotes the “grafting through” process but prevents more free growing chains to “graft through'' the polymerizable units.