Addition-fragmentation agents

1. An addition-fragmentation agent comprising: 1) a labile addition-fragmentation group, 2) a free-radically polymerizable group, and 3) a surface-modifying functional group that associates with the surface of a substrate, said addition-fragmentation agent of the formula:

wherein

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

Q is a covalent bond or a linking group, having a valence of m+1;

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

Z is an ethylenically unsaturated polymerizable group (meth)acryloxy, (meth)acrylamido, and styrenic groups,

Y is a functional group that bonds with a substrate on which the addition-fragmentation agent is disposed;

m is 1 to 6;

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.

2. The addition-fragmentation agent of claim 1 wherein at least one of R 1 , R 2 and R 3 contain both Z m -Q- and Y p -Q′-, where

Q is a covalent bond or a linking group, having a valence of m+1;

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

Z is an ethylenically unsaturated polymerizable group, and

Y is an functional group that bonds with a substrate on which the addition-fragmentation agent is disposed.

3. The addition-fragmentation agent of claim 1 wherein Q is selected from 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.

4. The addition-fragmentation agent of claim 1 where Q is an alkylene.

5. The addition-fragmentation agent of claim 1 where Q is a hydroxyl-substituted alkylene.

6. The addition-fragmentation agent of claim 1 where Q is an aryloxy-substituted alkylene.

7. The addition-fragmentation agent of claim 1 where Q is an alkoxy-substituted alkylene.

8. The addition-fragmentation agent of claim 1 wherein R 1 —X 1 — groups, and optionally R 2 —X 1 — and R 3 —X 1 — groups, are selected from H 2 C═C(CH 3 )C(O)—O—CH 2 —CH(OH)—CH 2 —O—, H 2 C═C(CH 3 )C(O)—O—CH 2 —CH(O—(O)C(CH 3 )═CH 2 )—CH 2 —O—, H 2 C═C(CH 3 )C(O)—O—CH(CH 2 OAr)—CH 2 —O—, H 2 C═C(CH 3 )C(O)—O—CH 2 CH 2 —N(H)—C(O)—O—CH(CH 2 OAr)—CH 2 —O—, H 2 C═C(H)C(O)—O—(CH 2 ) 4 —O—CH 2 —CH(OH)—CH 2 —O—, H 2 C═C(CH 3 )C(O)—O—CH 2 —CH(O—(O)C—N(H)—CH 2 CH 2 —O—(O)C(CH 3 )C═CH 2 )—CH 2 —O—, CH 3 —(CH 2 ) 7 —CH(O—(O)C—N(H)—CH 2 CH 2 —O—(O)C(CH 3 )C═CH 2 )—CH 2 —O—, H 2 C═C(H)C(O)—O—(CH 2 ) 4 —O—CH 2 —CH(—O—(O)C(H)═CH 2 )—CH 2 —O— and H 2 C═C(H)C(O)—O—CH 2 —CH(OH)—CH 2 —O—, where Ar is an aryl group.

9. The addition-fragmentation agent of claim 1 wherein Y 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.

10. The addition-fragmentation agent composition of claim 9 wherein Y 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.

11. A polymerizable composition comprising the addition-fragmentation agent of claim 1 , at least one free-radically polymerizable monomer, and an initiator.

12. The polymerizable composition of claim 11 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 10 parts by weight of the addition-fragmentation agent, based on 100 parts by weight of a) to e).

13. The polymerizable composition of claim 12 further comprising 0.01 to 5 parts of a multifunctional (meth)acrylate.

14. The polymerizable composition of claim 11 further comprising a surface-modified inorganic oxide of the formula:

where

Filler is an inorganic oxide particle,

R 2 and R 3 are each independently Z m -Q-, Y p -Q′-, a (hetero)alkyl group or a (hetero)aryl group;

Q is a covalent bond or a linking group, having a valence of m+1;

Q′ is a covalent bond or an or a linking group, having a valence of p+1;

Z is an ethylenically unsaturated polymerizable group (meth)acryloxy, (meth)acrylamido, and styrenic groups,

Y′ is the residue of the surface-modifying organic functional group that associates with a substrate on which the addition-fragmentation agent is disposed;

m is 1 to 6;

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.

15. A hardcoat composition comprising one or more multifunctional (meth)acrylate monomers or (meth)acrylate oligomers, and the addition-fragmentation agent of claim 1 .