Direct Synthesis of Porous Polyurea Films by Vapor Deposition Polymerization in Ionic Liquid

Most network-structured, porous polymer materials have so far been synthesized in bulk solution processes, which can sometimes be a drawback in their thin-film applications. In this communication, we propose a new route to the direct synthesis of porous polyurea (PU) films by vapor deposition polymerization in ionic liquid (IL), which is based on our original process "IL-assisted vacuum deposition". When 4,4'-methylenebis (2-chlorophenyl isocyanate) (MBCI) and 2,7-diaminofluorene (DAF) monomer molecules were codeposited onto an IL-coated substrate in vacuum, the PU films were found to have a percolated pore and network structure with a high degree of polymerization even without the postannealing treatment, which is required to proceed with the polymerization of PU films in the conventional vapor deposition polymerization. The porous PU film after annealing was still as rigid as the plain PU films and possessed a stronger water repellency, with contact angles exceeding 100°, than the plain PU films.