Silicic acid (hetero) polycondensate comprising structural units having the following formula in which the radicals, indices, and bonding symbols have the following meaning: R 1 refers to a group that is susceptible to a thiol-ene polyaddition when a thiol is added and can also be polymerized by a ROMP (ring opening metathesis polymerization), R 2 is selected from (a)organically polymerizable groups susceptible to a thiol-ene polyaddition when a thiol is added, but not to a ROMP, (b) -COOR 8 with R 8 equal to R 4 or M 1 / x x +, (c) -OH or COOH, and (d) - b P (R 5) 2, in which b is equal to 0 or 1, − SO 3 M 1 / x x +, NR 7 2 or NR 7 3 +, wherein M x+ is an x-fold positively charged metal cation, R 4 is a non-substituted or substituted hydrocarbon radical, the radicals R 5 independently represent a non-substituted or substituted hydrocarbon radical or OR 6, and R 6 is hydrogen or a non-substituted or substituted hydrocarbon radical, R 7 has either the same meaning as R 4 or two radicals R 7 together represent a divalent, substituted or non-substituted, saturated or unsaturated hydrocarbon group, R 3 represents a radical bonded to a silicon atom of said formula by a carbon atom, to which said radical R 1 is bonded o-fold and said radical R 2 is bonded n-fold and which is equivalent or has different meanings in the same condensate, each of the indices, n and o represents 0, 1, 2 or greater than 2 with the stipulation that n + o represents at least 2, at least one of the three bonds of a Si atom not further identified represents an oxygen bridge to an additional silicon atom or potentially to another metal atom, while the other two bonds either have the same meaning or instead represent an OH group, a hydrolysable group, or a radical bonded to the silicon atom via carbon, wherein each radical R 3 of said structure must have at least one group R 1 or one group R 2 having the meaning specified in (a) and then, if said radicals R 3 are equal, (x) each radical has at least one group R 1 and either one group R 2 with the meaning specified in (a) or a second group R 1 (i.e. in these cases, o = 2 or greater than 2), whereas in both cases, n must be at least 1, or (xx) if, in addition, n is equal to 0, at least two groups R 1 have a different meaning, and then, if said radicals R 3 are different, a first part of the radicals has at least one group R 1 and one of the following two conditions must be complied with: (x) an additional part of the radicals has at least one group R 2 with the meaning specified in (a) or (d), and (xx) two different radicals R 3 have at least one group R 1 (i.e. o = 1 or greater than 1). R 1 refers to a group that is susceptible to a thiol-ene polyaddition when a thiol is added and can also be polymerized by a ROMP (ring opening metathesis polymerization), R 2 is selected from (a)organically polymerizable groups susceptible to a thiol-ene polyaddition when a thiol is added, but not to a ROMP, (b) -COOR 8 with R 8 equal to R 4 or M 1 / x x +, (c) -OH or COOH, and (d) - b P (R 5) 2, in which b is equal to 0 or 1, − SO 3 M 1 / x x +, NR 7 2 or NR 7 3 +, wherein M x+ is an x-fold positively charged metal cation, R 4 is a non-substituted or substituted hydrocarbon radical, the radicals R 5 independently represent a non-substituted or substituted hydrocarbon radical or OR 6, and R 6 is hydrogen or a non-substituted or substituted hydrocarbon radical, R 7 has either the same meaning as R 4 or two radicals R 7 together represent a divalent, substituted or non-substituted, saturated or unsaturated hydrocarbon group, R 3 represents a radical bonded to a silicon atom of said formula by a carbon atom, to which said radical R 1 is bonded o-fold and said radical R 2 is bonded n-fold and which is equivalent or has different meanings in the same condensate, each of the indices, n and o represents 0, 1, 2 or greater than 2 with the stipulation that n + o represents at least 2, at least one of the three bonds of a Si atom not further identified represents an oxygen bridge to an additional silicon atom or potentially to another metal atom, while the other two bonds either have the same meaning or instead represent an OH group, a hydrolysable group, or a radical bonded to the silicon atom via carbon, wherein each radical R 3 of said structure must have at least one group R 1 or one group R 2 having the meaning specified in (a) and then, if said radicals R 3 are equal, (x) each radical has at least one group R 1 and either one group R 2 with the meaning specified in (a) or a second group R 1 (i.e. in these cases, o = 2 or greater than 2), whereas in both cases, n must be at least 1, or (xx) if, in addition, n is equal to 0, at least two groups R 1 have a different meaning, and (x) each radical has at least one group R 1 and either one group R 2 with the meaning specified in (a) or a second group R 1 (i.e. in these cases, o = 2 or greater than 2), whereas in both cases, n must be at least 1, or (xx) if, in addition, n is equal to 0, at least two groups R 1 have a different meaning, and then, if said radicals R 3 are different, a first part of the radicals has at least one group R 1 and one of the following two conditions must be complied with: (x) an additional part of the radicals has at least one group R 2 with the meaning specified in (a) or (d), and (xx) two different radicals R 3 have at least one group R 1 (i.e. o = 1 or greater than 1). (x) an additional part of the radicals has at least one group R 2 with the meaning specified in (a) or (d), and (xx) two different radicals R 3 have at least one group R 1 (i.e. o = 1 or greater than 1).