The invention relates to compounds of formula (I) (XaRbSi)m[(B) ([O]oP[O]pR'cYd)n]4-a-b (I), where the groups, residues and indices have the following meanings: B=an at least doubly-valent straight chained or branched group with at least one organic polymerizable group and at least three carbon atoms, X=a group which may be cleaved from the silicon atom by hydrolysis, R=optionally substituted alkyl, alkanyl, aryl, alkylaryl or arylalkyl, R'.dbd.R, Y.dbd.Cl, OH or OR', R''.dbd.H, alkyl or aryl, a=0, 1, 2 or 3, b=0, 1 or 2, a+b together=1, 2 or 3, c=0, 1 or 2, d=0, 1 or 2, c+d together=2, m=at least 1, with the proviso that m is not greater than 1 when a+b=1 or 2, n=at least 1, o=0 or 1 and p=0 or 1. The invention further relates to a series of methods by which the above compounds may be produced.