Self-healing siloxane elastomers
The present disclosure relates to self-healing siloxane elastomers. In particular, the present disclosure relates to self-healing siloxane elastomers comprising at least one siloxane polymer reversibly crosslinked to a second siloxane oligomer or polymer, the reversible cross-linked may be formed at ambient temperature.
1 . A siloxane elastomer, comprising
a) at least one siloxane polymer which is functionalized with at least one first Diels-Alder moiety, wherein the first Diels-Alder moiety comprises a diene; and
b) a crosslinker having maleimide moieties and having the structure
wherein R 1 and R 2 are independently or simultaneously —(C 1 -C 10 )-alkyl, —(C 2 -C 10 )-alkenyl, —(C 2 -C 10 )-alkynyl, or —(C 6 -C 10 )-aryl;
v is an integer from 1 to 10; and
wherein the first Diels-Alder moiety and the maleimide moieties form reversible crosslinks to form the siloxane elastomer, and wherein the first Diels-Alder moiety has the structure
wherein y is an integer between 1 and 10, and
represents the connection to the siloxane.
2 . The siloxane elastomer of claim 1 , wherein the siloxane polymer has the structure
wherein m represents the molar ratio of the monomer and is between about 0.1 to about 20.0 mol %; and
n represents the molar ratio of the monomer and is between about 80.0 to about 99.9 mol %.
3 . The siloxane elastomer of claim 1 , wherein v is 1, 2 or 3.
4 . The siloxane elastomer of claim 1 , wherein the crosslinker has the structure
5 . The siloxane elastomer of claim 1 , wherein the reversible crosslinks form at a temperature from about 20° C. to about 30° C.
6 . The siloxane elastomer of claim 1 , wherein R 1 and R 2 are independently or simultaneously —(C 1 -C 6 )-alkyl.
7 . The siloxane elastomer of claim 6 , wherein R 1 and R 2 are CH 3 .
8 . The siloxane elastomer of claim 1 , wherein the at least one siloxane polymer is a trimethylsilyl terminated copolymer comprising monomeric units of:
a) a first monomer which is a dimethylsiloxane;
b) a second monomer, which is formed from a methylhydrosiloxane, wherein the methylhydrosiloxane is functionalized with the at least one first Diels-Alder moiety.
9 . The siloxane elastomer of claim 8 , wherein the dimethylsiloxane has the structure
10 . The siloxane elastomer of claim 8 , wherein the methylhydrosiloxane has the structure
which is converted to a monomer having the structure
wherein D is a moiety containing the first Diels-Alder moiety.
11 . The siloxane elastomer of claim 10 , wherein the moiety D is
wherein y is an integer between 1 and 10, and
represents the connection to the siloxane.
12 . The siloxane elastomer of claim 1 , wherein the at least one siloxane polymer is a siloxane having the structure
wherein
each R is independently or simultaneously —(C 1 -C 10 )-alkyl, —(C 2 -C 10 )-alkenyl, —(C 2 -C 10 )-alkynyl, or —(C 6 -C 10 )-aryl;
each R′ is a suitable terminal group, and
n is an integer between 1 and 1,000,
and wherein a portion of the R groups are replaced with a group comprising the first Diels-Alder moiety.
13 . The siloxane elastomer of claim 12 , wherein each R is independently or simultaneously is —(C 1 -C 6 )-alkyl, —(C 2 -C 6 )-alkenyl, —(C 2 -C 6 )-alkynyl, or phenyl.
14 . The siloxane elastomer of claim 13 , wherein each R is methyl.
15 . The siloxane elastomer of claim 14 , wherein each R is methyl, and between 1% and 60% of the methyl groups are replaced with a group comprising the first Diels-Alder moiety.
16 . The siloxane elastomer of claim 12 , wherein R′ is OH or —(C 1 -C 6 )-alkyl.
17 . The siloxane elastomer of claim 16 , wherein R′ is CH 3 .
18 . A siloxane elastomer, comprising
a) at least one siloxane polymer having the structure
wherein w is an integer between 1 and 10;
m represents the molar ratio of the monomer and is between about 0.1 to about 20.0 mol %; and
n represents the molar ratio of the monomer and is between about 80.0 to about 99.9 mol %,
and each R is independently or simultaneously —(C 1 -C 10 )-alkyl, —(C 2 -C 10 )-alkenyl, —(C 2 -C 10 )-alkynyl, or —(C 6 -C 10 )-aryl; and
b) a crosslinker having maleimide moieties and having the structure