Novel organosilicon compounds which comprise multifunctional POSs, characterized in that the said multifunctional POSs contain identical or different units of formula:
- 2 ( R 2 ) a Y b X c SiO 4 - ( a + b + c ) 2 ( I )
- in which:
- (1) the symbols R2, which may be identical or different, each represent a monovalent hydrocarbon-based group chosen from a linear or branched alkyl radical containing from 1 to 6 carbon atoms, a cycloalkyl radical containing from 5 to 8 carbon atoms and a phenyl radical;
- (2) the symbols Y, which may be identical or different, each represent a hydroxyl or alkoxy function R1O in which R1 represents a linear or branched alkyl radical containing from 1 to 15 carbon atoms;
- (3) the symbols X, which may be identical or different, each represent a function bearing an activated ethylenic double bond, chosen from the radicals having the formulae (II/1), (II/2) and (II/3) below, and mixtures thereof:
- 21
- with the conditions according to which:
- at least one of the functions X corresponds to formula (II/1),
- when, where appropriate, there is a mixture of function(s) X of formula (II/1) with functions X of formulae (II/2) and/or (II/3), the mole fraction of functions X of formulae (II/2) and/or (II/3) in all of the functions X is on average less than or equal to 12 mol %,
- formulae in which:
- R3 is a linear or branched divalent alkylene radical containing from 1 to 15 carbon atoms, the free valency of which is borne by a carbon atom and is linked to a silicon atom, the said radical R3 possibly being interrupted in the alkylene chain with at least one hetero atom (such as oxygen and nitrogen) or at least one divalent group comprising at least one hetero atom (such as oxygen and nitrogen), and in particular with at least one divalent residue of general formula V1radicalV2chosen from:
- —O—, —CO—, —CO—O—, —COO-cyclohexylene (optionally substituted with an OH radical)-, —O-alkylene (linear or branched C2-C6, optionally substituted with an OH or COOH radical)-, —O—CO-alkylene (linear or branched C2-C6, optionally substituted with an OH or COOH radical)-, —CO—NH—, O—CO—NH— and —NH-alkylene (linear or branched C2-C6)—CO—NH—;
- R3 also represents a divalent aromatic radical of general formula {fraction (V1)}radical{fraction (V2)}chosen from:
- -(ortho, meta or para)phenylene(linear or branched C2-C6)alkylene-, -(ortho, meta or para)phenylene-O-(linear or branched C2-C6)alkylene-, -(linear or branched C2-C6)alkylene-(ortho, meta or para)phenylene(linear or branched C1-C6)alkylene-, and -(linear or branched C2-C6)alkylene(ortho, meta or para)phenylene-O-(linear or branched C1-C6)alkylene-;
- preferably, the symbol R3 represents an alkylene radical which corresponds to the following formulae:
- —(CH2)2—, —(CH2)3—, —(CH2)4—, —CH2—CH(CH3)—, —(CH2)2—CH(CH3)—CH2—, —(CH2)3—O—(CH2)3—, —(CH2)3—O—CH2—CH(CH3)—CH2—, —(CH2)3—O—CH2CH(OH)—CH2—;
- more preferably, R3 is a —(CH2)2— or —(CH2)3-radical;
- with the specific detail that, in the preceding definitions of R3, when the divalent residues and radicals mentioned are not symmetrical, they may be positioned with the valency v1 to the left and the valency v2 to the right, or vice versa with the valency v2 to the left and the valency v1 to the right;
- the symbols R4 and R5, which may be identical or different, each represent a hydrogen atom, a halogen atom, a cyano radical, a linear or branched alkyl radical containing from 1 to 6 carbon atoms;
- (4) the symbols a, b and c each represent integers or fractions chosen from:
- a:
- 0, 1, 2or 3;
- b:
- 0, 1, 2or 3;
- c:
- 0 or 1;
- the sum a+b+c being other than zero and ≦3;
- (5) the content of units R6SiO3/2 (units “T”) in which R6 is chosen from the radicals corresponding to the definitions of R2, Y and X, this content being expressed as the number, per molecule, of these units per 100 silicon atoms, is less than or equal to 30%;
- (6) the content of functions Y, expressed as the number, per molecule, of functions Y per 100 silicon atoms, is at least 0.8%;
- (7) the content of functions X, expressed as the number, per molecule, of functions X per 100 silicon atoms, is at least 0.4%.