Cosmetic or dermatological compositions of polyurethane and/or polyurea block polycondensation products containing silicon grafts and their use

A composition comprising at least one polyurethane and/or polyurea block polycondensation product, wherein said product comprises a chain containing the repetition of at least one polyurethane and/or polyurea block -{-M-}- having the following formula (I):

• wherein
• X1 independently represents —O— or —NH—;
• D represents a segment of formula:
• in which Z is a trivalent hydrocarbon radical chosen from the radicals
• wherein a is an integer ranging from 1 to 10;
• and
• Q is a polysiloxane segment of formula (I′):
• wherein the radicals R1 are chosen from C1-C20 monovalent hydrocarbon, halohydrocarbon, and perhalogenated radicals which are free or substantially free from ethylenic unsaturation, and aromatic radicals, and m is an integer such that the average molecular weight, measured at the top of the GPC peak, of the polysiloxane segment, ranges from 300 to 50,000,
• R is a divalent radical selected from aliphatic, cycloaliphatic and aromatic radicals,
• wherein said block -{-M-}- includes a polysiloxane graft, and
• wherein said composition is a cosmetic or dermatological composition.