| abstract |
Three methods for the preparation of polyhedral oligomeric silsesquioxanes (POSS) using the action of bases capable of attacking silicon atoms or any other compounds capable of reacting with protic solvents (such as ROH, H2O , etc.) [OH] - , alkoxide [RO] - and other compounds. The first method utilizes these bases to effectively redistribute the silicon-oxygen skeleton structure in the polymerized silsesquioxane [RSiO 1.5 ] ∞ into POSS nanostructures, which are represented by the formula [(RSiO 1.5 ) n ] ∑# The homoleptic segment shown in [(RXSiO 1.5 ) n ] ∑# , the heteroleptic segment shown in [(RSiO 1.5 ) m (R'SiO 1.5 ) n ] ∑# and {(RSiO 1.5 ) m (RXSiO 1.0 ) n } Functionalized heterosegment nanostructures shown in Σ# , where ∞=1－1,000,000 or higher. The second method uses a base to help form POSS nanostructures from silane RSiX 3 and linear or cyclic silsesquioxanes of the formula RX 2 Si—(OSiRX) m —OSiRX 2 , that is, the formula [(RSiO 1.5 ) n ] ∑# , the homogeneous segment shown and the hetero segment shown in [(RSiO 1.5 ) m (R'SiO 1.5 ) n ] ∑# and the functional group shown in [(RSiO 1.5 ) m (RXSiO 1.0 ) n ] ∑# The hybrid fragment nanostructure, wherein, m=0-10, X=OH, Cl, Br, I, alkoxide OR, acetate OOCR, peroxide OOR, amine NR 2 , isocyanate NCO and R. The third method utilizes bases to selectively open silicon-oxygen-silicon (Si-O-Si) bonds in the POSS structure to form POSS species with incompletely condensed nanostructures. These methods also provide control over the stereochemistry of X. The three methods can generate new POSS species, which can be finally transformed into POSS species suitable for polymerization, grafting or other desired chemical reactions after additional chemical control. |