Abstract: Oligomers of the formula: [R3SiO½]m[O½Si(R2)O½]n[SiO{fraction (3/2)}R]o[SiO{fraction (4/2)}]p  (I) wherein each R is selected individually from the group consisting of B, R1,—OR2, R3 and R4; B is an organosilyl functional group bridged to the Si atom of the siloxane oligomer backbone by an Si—C bond; each R1 is independently a saturated or aromatic hydrocarbon group of 1 to 16 carbon atoms; each R2 is independently a group as defined for R1 or an acyl group; and each R3 is independently a monovalent organic radical containing an aliphatically unsaturated hydrocarbon group and each R4 is a monovalent organic radical linked to the Si atom of the siloxane oligomer backbone by an Si—C bond, which does not include an aliphatically unsaturated hydrocarbon group and which has thereon one or more members of the group selected from ether, polyether, ester, polyester, carbamate, polyurethane, isocyanurate, thioether, polysulfide