Molecular Hybrid Optical Limiting Materials from Polyhedral Oligomer Silsequioxane: Preparation and Relationship between Molecular Structure and Properties

A series of new molecular hybrids with stilbene chromophore (H1-H4) are prepared by hydrosilylation of octahydridosilsesquioxane (T-8(H)). All these stilbene-containing hybrid materials arc soluble in common organic solvents, such as chloroform, toluene, THF, and 1,2-dichloroethane, and possess good film-forming properties. Their structures and properties are characterized and evaluated by FT-IR, NMR, UV, PL, TGA, DSC, nonlinear optical (NLO), and optical limiting (OL) analyses. The results show that the thermal decomposition temperatures (T-d, 5 mass % loss) of the hybrids are 20-60 degrees C greater than their corresponding stilbene monomers, and the hybrids show obvious nonlinear absorption (beta up to 2.56 x 10(-11) m/W) and optical limiting properties. The larger excited-state absorption cross sections than corresponding ground-state absorption cross sections of the hybrids indicate that reverse saturable absorption is a major mechanism responsible for the optical limiting of the hybrids.