Addition-fragmentation agents

1. A polymerizable composition comprising the addition-fragmentation agent comprising: 1) a labile addition-fragmentation group, and 2) at least two surface-binding functional groups, of the formula:

wherein

R 1 , R 2 and R 3 are each independently Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least two of R 1 , R 2 and R 3 is Y p -Q′-

Q′ is a covalent bond or (hetero)hydrocarbyl linking group, having a valence of p+1;

Y is a surface-binding functional group;

p is 1 or 2;

each X 1 is independently —O— or —NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1;

at least one free-radically polymerizable monomer, and an initiator.

2. The polymerizable composition of claim 1 comprising:

a) 85 to 100 parts by weight of an (meth)acrylic acid ester;

b) 0 to 15 parts by weight of an acid functional ethylenically unsaturated monomer;

c) 0 to 10 parts by weight of a non-acid functional, ethylenically unsaturated polar monomer;

d) 0 to 5 parts vinyl monomer; and

e) 0 to 5 parts of a multifunctional (meth)acrylate;

based on 100 parts by weight total monomer a) to e), and

f) 0.1 to 12 parts by weight of the addition-fragmentation agent, based on 100 parts by weight of a) to e), and

g) an initiator.

3. The polymerizable composition of claim 2 further comprising 0.01 to 5 parts of a multifunctional (meth)acrylate.

4. The polymerizable composition of claim 1 , wherein at least one of R 1 , R 2 and R 3 of the addition-fragmentation agent contain more than one Y p -Q′-, where

Q′ is a covalent bond or a (hetero)hydrocarbyl linking group, having a valence of p+1;

p is 1 or 2; and

Y is a surface-binding functional group.

5. The polymerizable composition of claim 1 wherein Q′ of the addition-fragmentation agent is selected from —O—, —S—, —NR 4 —, —SO 2 —, —PO 2 —, —CO—, —OCO—, —R 6 —, —NR 4 —CO—NR 4 —, NR 4 —CO—O—, NR 4 —CO—NR 4 —CO—O—R 6 —, —CO—NR 4 —R 6 —, —R 6 —CO—O—R 6 —, —O—R 6 —, —S—R 6 —, —NR 4 —R 6 —, —SO 2 —R 6 —, —PO 2 —R 6 —, —CO—R 6 —, —OCO—R 6 —, —NR 4 —CO—R 6 —, NR 4 —R 6 —CO—O—, and NR 4 —CO—NR 4 —,

wherein each R 4 is hydrogen, a C 1 to C 4 alkyl group, or aryl group, each R 6 is an alkylene group having 1 to 6 carbon atoms, a 5- or 6-membered cycloalkylene group having 5 to 10 carbon atoms, or a divalent arylene group having 6 to 16 carbon atoms, with the proviso that Q-Z does not contain peroxidic linkages.

6. The polymerizable composition of claim 1 where Q′ of the addition-fragmentation agent is an alkylene, of the formula —CrH 2r —, where r is 1 to 10.

7. The polymerizable composition of claim 1 where Q′ of the addition-fragmentation agent is a hydroxyl-substituted alkylene.

8. The polymerizable composition of claim 1 where Q′ of the addition-fragmentation agent is —CH 2 —CH(OH)—CH 2 —.

9. The polymerizable composition of claim 1 where Q′ of the addition-fragmentation agent is an aryloxy-substituted alkylene, or an alkoxy-substituted alkylene.

10. The polymerizable composition of claim 1 wherein Y of the addition-fragmentation agent is a monophosphate, a phosphonate, a phosphonic acid, a hydroxamic acid, a carboxylic acid, and acetoacetate, an anhydride, an isonitrile group, a silyl, a disulfide, a thiol, an amino, a sulfinic acid, a sulfonic acid, a phosphine, a phenolic or a heterocyclic aromatic group.

11. polymerizable composition of claim 10 wherein Y of the addition-fragmentation agent is a silyl group of the formula: —SiR 7 3, wherein each R 7 group is independently selected from the group of alkoxy, acetoxy, and halide.

12. The polymerizable composition of claim 1 , further comprising a surface-modified inorganic oxide of the formula:

where

Filler is an inorganic filler particle,

R 2 is Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group;

Q′ is a covalent bond or an or a (hetero)hydrocarbyl linking group having a valence of p+1;

Y′ is the residue of the surface-binding functional group Y;

p is 1 or 2;

X i is independently —O—or —NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1.

13. A hardcoat composition comprising one or more multifunctional (meth)acrylate monomers or (meth)acrylate oligomers, and the addition-fragmentation agent comprising: 1) a labile addition-fragmentation group, and 2) at least two surface-binding functional groups, of the formula:

wherein

R 1 , R 2 and R 3 are each independently Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group with the proviso that at least two of R 1 , R 2 and R 3 is Y p -Q′-

Q′ is a covalent bond or a (hetero)hydrocarbyl linking group, having a valence of p+1;

Y is a surface-binding functional group;

p is 1 or 2;

each X 1 is independently —O—or —NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1;

at least one free-radically polymerizable monomer, and an initiator.

14. A hardcoat composition comprising one or more multifunctional (meth)acrylate monomers or (meth)acrylate oligomers, and a surface-modified inorganic oxide of the formula:

where

Filler is an inorganic filler particle,

R 2 is Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group;

Q′ is a covalent bond or an or a (hetero)hydrocarbyl linking group having a valence of p+1;

Y′ is the residue of the surface-binding functional group Y;

p is 1 or 2;

X 1 is independently —O—or—NR 4 —, where R 4 is H or C 1 -C 4 alkyl, and

n is 0 or 1.