Preparation of ultrathin films of molecular networks through layer-by-layer cross-linking polymerization of tetrafunctional monomers

摘要

The synthesis of nanometers-thick films of rigid organic molecular networks via layer-by-layer crosslinking polymerization, a type of molecular layer deposition method, was demonstrated. To optimize the deposition conditions to full surface coverage, various films were grown using different monomer concentrations of dipping solutions and varying the duration of substrate immersion in each dipping run. It is found that the covalent grafting of the tetrahedral monomers onto the growing film surface ceases after a critical immersion time for which the surface becomes saturated with the adsorbed countermonomers. Examination of a plot of film thickness as a function of deposition cycle number discloses a linear trend line of slope 1.94 nm/cycle, which is an approximate measure of the film thickness per deposition cycle.