Organic-inorganic polycondensate and a method of obtaining the same

A method of manufacturing an organic-inorganic polycondensate which satisfies the following formula:

• C.sub.v H.sub.w O.sub.x Si.sub.y Me.sub.z
• where:
• v=4 to 48
• w=5 to 52
• x=5 to 48
• y=2 to 16
• z=1
• the ratio v/(y+z) being less than 7;
• and
• Me being a metal or a mixture of metals selected from the group consisting of Ti, Zr, Hf, Ta, W and Al;
• said method comprising, in a first step, a liquid precursor is made having a polymerizable functional group carried by the carbon-containing group of silicone, and that, in a second step, said precursor is cross-linked by raising its temperature and/or exposing it to ultraviolet radiation;
• said first step consisting in causing:
• at least one metal derivative of formula MeR.sub.x where:
• R represents a hydrolyzable group, or a hydroxy group;
• and X represents the valence of the metal element;
• to react with at least one functionalized silane of formula R'.sub.n Si(R"Y)(4-n) where:
• R' represents at least one hydrolyzable group or a hydroxy group;
• R"Y represents a functionalized and nonhydrolyzable group in which R" represents a carbon-containing, saturated, unsaturated, cyclic or aromatic group, optionally containing at least one hetero atom, and Y represents a remainder that is reactive under the reaction conditions and that is selected from the group consisting of an epoxy group, an unsaturate group, a vinyl group and an allyl group;
• and n is less than 4;
• and further, in said first step:
• firstly said functionalized silane is partially pre-hydrolyzed by adding water, in an acid medium or a basic medium, optionally in an organic medium, the quantity of added water being less than the stoichiometric quantity;
• said metal derivative is then added and it condenses;
• the condensation reaction is continued with a reflux step which enables the molecular polycondensation to be completed;
• and
• distillation or evaporation is then performed.