Polyurethane has polyether blocks and polyester and alkoxysilane terminal group

1) A process for preparing a polyurethane polyurethane-polyether blocks and polyurethane-polyester with at least two polyurethane-polyester terminal blocks connected to a terminal alkoxysilane group, said method comprising: (i) reacting a polyether polyol (A ) with a stoichiometric excess of an aliphatic diisocyanate (B), then (ii) reacting the polyurethane formed in step (i) with a stoichiometric excess of a polyester polyol (C), then (iii) reacting the polyurethane formed in step (ii) with a stoichiometric amount of a isocyanatosilane (D). 2) Polyurethane formed by said method 3) corresponding adhesive composition further comprising a crosslinking catalyst. 4) A method for joining two substrates using said composition.