Synthesis and molecular structure of [Ti-4(OPri)(8)(mu,eta(2)-OCH2CH = CHCH2O)(2)(mu(3),eta(2)-OCH2CH = CHCH2O)(2)]. Application to the elaboration of low density, microcellular, doped organic materials

The reaction between Ti(OPri)(4) and cis-but-2-ene-1,4-diol [HOCH2CH=CHCH2O H] in 1 : 1 stoichiometry at room temperature gave [Ti-4(OPri)(8)(mu,eta(2) -OCH2CH=CHCH2O)(2)(mu(3),eta(2)-OCH2CH=CHCH2O)(2)] 1 which was characterize d by single crystal X-ray diffraction. Its molecular structure consists of an open-shell tetranuclear polyhedron with terminal isopropoxide ligands wh ile the unsaturated diolates act as bridging-chelating ligands assembling f ive- and six-coordinated metals. The Ti-O bond lengths are in the range 1.7 7(1)-2.12(1) Angstrom with Ti-OPri< Ti-eta(2)-OC6H4O < Ti-mu-OC6H4O. Compou nd 1 was used for doping polystyrene foams elaborated by a emulsion/polymer ization (w/o) process with traces of titania. Microcellular polystyrene foa ms with a low density (0.048-0.055 cm(-3)) doped with titania (0.72-1.5 Ti wt%) have been obtained. The influence of a number of parameters such as th e nature of the radical initiator, of the precursor, of an electrolyte and of the amount of surfactant, on the properties of the foams has been evalua ted. The influence of various polymerizable ligands, but-2-ene-1,4-diolate, 2-(methacryloyloxy)ethyl acetoacetate and 3-allyloxy-1,2-propanediolate, h as been investigated. The results indicate the first of these to give the b est results. The precursors were characterized by FTIR, H-1 NMR, elemental analysis and the foams by IR, elemental analysis, SEM/EDX and compressibili ty measurements.