Energetic Characteristics\nof Hydrophobic Porous Materials\nas Candidates for Manufacturing of Nanorockets

A new propulsion mechanism for nano- and microrocket\nengines is\nhypothesized. It is based on the instantaneous expulsion from hydrophobic\nnanopores triggered by irradiation from electromagnetic microwaves,\nultrasound, or sudden pressure release. A large energy output is needed\nfor the propulsion of a nanoparticle, and the value can be determined\nexperimentally and by means of atomistic simulations. As such, we\nmeasured the heat of intrusion of water into ITQ-29 (LTA) pure silica\nzeolite with cage structure of pores. The heat effect is exothermic\nand equal to −7.3 ± 0.8 J/g of zeolite. Similar values\nwere reported for chabazite, ZIF-8, and grafted mesoporous silica\nEVA. All these materials have cage structures of pores. In contrast,\nsilicalite-1 (MFI) zeolite with a channel structure of pores exhibits\nendothermic intrusion. Molecular dynamics simulations of pure silica\nzeolites with LTA, CHA, and MFI topologies at a broad range of water\nloadings show that water becomes thermodynamically stable in cage-shaped\npores while it is unstable in channel-shaped pores. A large energy\nrelease is expected during water expulsion from channel-type pores.