Two-Dimensional Polyamide Networks with a Broad Pore Size Distribution on the Ag(111) Surface

Covalently bonded, two-dimensional polyamide networks were prepared by vaccum deposition polymerization under ultra-high vacuum conditions on the Ag(111) surface. By a careful choice of the annealing conditions, ordered domains of the corresponding oligomers could be also achieved. The layers were characterized by scanning tunneling microscopy. We used the step growth polymerization between a trifunctional acid chloride and a bifunctional amine, taking place directly on the surface. The resulting polymer networks are nonuniform and show an open porous structure with a broad distribution of pore sizes. Besides large pores of varying shape, also small, 8- to 12-membered polymer rings with a regular shape are formed. A detailed analysis of the pore size distribution gives insight into the influence of the kinetic preference and the role of conformational flexibility for the formation of disordered covalent networks.