Acrylic polymers having controlled placement of functional groups
Acrylic copolymers that include the controlled placement of functional groups within the polymer structure are provided. The copolymers contain a reactive segment and a non-reactive segment and are manufactured via a controlled radical polymerization process. The copolymers are useful in the manufacture of adhesives and elastomers.
1. A crosslinkable composition comprising:
at least one acrylic copolymer comprising at least one reactive segment of controlled size and position and at least one non-reactive segment of controlled size and position,
the at least one reactive segment comprising copolymers derived from (i) one or more of monomers of at least one non-reactive segment and (ii) at least one polymerizable comonomer comprising a crosslinkable functionality,
wherein the one or more monomers of the at least one non-reactive segment is the same type of monomer of the at least one non-reactive segment present in the at least one reactive segment,
wherein the one or more monomers of the at least one non-reactive segment are present in the at least one reactive segment in an amount effective for the at least one reactive segment and the at least one non-reactive segment to be molecularly miscible before cure, and
wherein the at least one non-reactive segment of the acrylic copolymer is derived from monomers selected from the group consisting of C 1 to about C 20 alkyl, aryl, or cyclic acrylates, C 1 to about C 20 alkyl, aryl, or cyclic methacrylates, or mixtures thereof.
2. The composition of claim 1 comprising two reactive segments and one non-reactive segment.
3. The composition of claim 1 comprising one reactive segment and two non-reactive segments.
4. The composition of claim 1 comprising a first reactive segment comprising a monomer having a first functional group, and a second reactive segment comprising a monomer having a second functional group.
5. The composition of claim 1 wherein the at least one reactive segment comprises at least one monomer having the formula:
where R is H or CH 3 and X represents or contains a functional group capable of crosslinking.
6. The composition of claim 1 wherein the at least one reactive segment contains at least one functional group chosen from silyl, hydroxyl, carboxyl, carbonyl, carbonate ester, isocyanate, anhydride, acidic, epoxy, vinyl, (meth)acrylate, amino, amide, imide, siloxy, mercapto, thiol, alkoxy, oxazole, acetoacetyl, acetoacetoxy, and acrylamide groups.
7. The composition of claim 1 wherein the at least one reactive segment comprises at least one monomer having the formula:
where R 3 is H or CH 3 and R 4 is a branched or unbranched, saturated alkyl group having 4 to 14 carbon atoms.
8. The composition of claim 1 wherein the at least one reactive segment comprises an unsaturated carboxylic acid containing from 3 to about 20 carbon atoms.
9. The composition of claim 1 wherein the at least one reactive segment comprises an acrylamide.
10. The composition of claim 1 wherein the position of the at least one reactive segment and the at least one non-reactive segment are controlled by RAFT agent.
11. The composition of claim 1 wherein the position of the at least one reactive segment and the at least one non-reactive segment are controlled by a SFRP agent.
12. The composition of claim 1 wherein the average molecular weight (Mn) of the at least one acrylic copolymer is in the range of about 10,000 g/mole to about 200,000 g/mole.
13. The composition of claim 1 wherein the average molecular weight (Mn) of the at least one acrylic copolymer is in the range of about 25,000 g/mole to about 75,000 g/mole.
14. The composition of claim 1 further comprising a crosslinker.
15. The composition of claim 1 wherein the at least one acrylic copolymer has a polydispersity of less than 3.0.
16. A pressure sensitive adhesive comprising the composition of claim 1 ,
wherein the crosslinkable functional groups are crosslinked.
17. A foam comprising the composition of claim 1 .
18. An elastomer comprising the composition of claim 1 .
19. The pressure sensitive adhesive of claim 16 further comprising a tackifier.
20. The composition of claim 1 wherein the at least one reactive segment comprises at least two reactive functional groups.
21. A method of preparing a pressure sensitive adhesive comprising the steps of:
polymerizing using a controlled radical polymerization process at least one monomer comprising at least one reactive functional group capable of undergoing a crosslinking reaction to form a reactive segment of controlled molecular weight and position;
polymerizing using a controlled radical polymerization process at least one monomer that is non-reactive with the reactive functional group of the reactive segments to form one non-reactive segment of controlled molecular weight and position;
forming an acrylic polymer from the reactive segment and the non-reactive segment;
crosslinking the acrylic polymer by mixing the acrylic polymer with an amount of a crosslinking agent;
wherein the one or more monomers of the non-reactive segment are present in the reactive segment in an amount effective for the reactive segments and the non-reactive segment to be molecularly miscible before cure,
the reactive segments comprising copolymers derived from (i) one or more of the monomers of the non-reactive segment and (ii) at least one polymerizable comonomer comprising a crosslinkable functionality, and
wherein the non-reactive segment of the acrylic copolymer is derived from monomers selected from the group consisting of C 1 to about C 20 alkyl, aryl, or cyclic acrylates, C 1 to about C 20 alkyl, aryl, or cyclic methacrylates, or mixtures thereof.
22. The method of claim 21 wherein the reactive segment is polymerized first in the presence of a RAFT agent.
23. The method of claim 21 wherein the non-reactive segment is polymerized first in the presence of a RAFT agent, the polymerization is terminated after the complete conversion of the at least one monomer comprising at least one reactive functional group to form the reactive segment(s).
24. The method of claim 21 wherein the non-reactive segment is polymerized first in the presence of an SFRP agent.
25. The method of claim 21 wherein the reactive segment is polymerized first in the presence of an SFRP agent.
26. The method of claim 21 further comprising the step of crosslinking the functional groups of the reactive segment.
27. The composition of claim 1 wherein the at least one non-reactive segment being non-reactive with the functional group of the at least one reactive segment.
28. The composition of claim 1 wherein the functional group is in a non-terminal position in the copolymer.
29. The composition of claim 1 wherein the position of the at least one reactive segment and the at least one non-reactive segment are controlled by a controlled radical polymerization process.
30. The composition of claim 1 wherein the position of the at least one reactive segment and the at least one non-reactive segment are controlled by a controlled radical polymerization process selected from the group consisting of atom-transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), stable free radical polymerization (SFRP), and nitroxide-mediated polymerization (NMP).
31. A crosslinkable composition comprising:
at least one acrylic copolymer comprising at least one reactive segment of controlled size and position and at least one non-reactive segment of controlled size and position,
the at least one reactive segment comprising copolymers derived from (i) one or more monomers of the at least one non-reactive segment and (ii) at least one polymerizable comonomer comprising a crosslinkable functionality,
wherein the one or more monomers of the at least one non-reactive segment are present in the at least one reactive segment in an amount effective for the at least one reactive segment and the at least one non-reactive segment to be molecularly miscible before cure.
32. The composition of claim 31 wherein the one or more monomers present in the at least one non-reactive segment is the same type of monomer of the at least one non-reactive segment present in the at least one reactive segment.
33. The composition of claim 31 wherein the at least one reactive segment comprises at least one monomer having the formula:
where R is H or CH 3 and X represents or contains a functional group capable of crosslinking.
34. The composition of claim 31 wherein the at least one reactive segment contains at least one functional group chosen from silyl, hydroxyl, carboxyl, carbonyl, carbonate ester, isocyanate, anhydride, acidic, epoxy, vinyl, (meth)acrylate, amino, amide, imide, siloxy, mercapto, thiol, alkoxy, oxazole, acetoacetyl, acetoacetoxy, and acrylamide groups.
35. The composition of claim 31 wherein the at least one non-reactive segment of the acrylic copolymer is derived from one or more monomers selected from the group consisting of C 1 to about C 20 alkyl, aryl, or cyclic acrylates, C 1 to about C 20 alkyl, aryl, or cyclic methacrylates, or mixtures thereof.
36. The composition of claim 31 wherein the functional group is in a non-terminal position in the copolymer.