Anisotropic thermally conductive polymers with dynamic molecular weight, and methods of making the same
Some variations provide an oligomer composition comprising: polarizable first thermotropic liquid-crystal oligomer molecules (preferably urethanes or ureas) containing first triggerable reactive end groups, wherein the first triggerable reactive end groups are selected from the group consisting of hydroxyl, isocyanate, blocked isocyanate, acrylate, epoxide, amine, vinyl, ester, thiol, conjugated diene, substituted alkene, furan, maleimide, anthracene, and combinations thereof, and wherein the polarizable first thermotropic liquid-crystal oligomer molecules are characterized by a weight-average molecular weight from about 200 g/mol to about 10,000 g/mol; optionally, a plurality of polarizable second thermotropic liquid-crystal oligomer molecules containing second triggerable reactive end groups, wherein the second triggerable reactive end groups are capable of reacting with the first triggerable reactive end groups; and optionally, a reactive coupling agent capable of reacting with the first triggerable reactive end groups. Methods are described for converting the oligomer composition into an anisotropic thermally conductive polymer. Many commercial uses are disclosed.
1. An oligomer composition comprising:
(a) a plurality of first thermotropic liquid-crystal oligomer molecules containing first triggerable reactive end groups,
wherein said first thermotropic liquid-crystal oligomer molecules are selected from oligourethanes, oligoureas, or a combination thereof,
wherein said first triggerable reactive end groups are selected from the group consisting of hydroxyl, isocyanate, blocked isocyanate, acrylate, epoxide, amine, vinyl, ester, thiol, conjugated diene, substituted alkene, furan, maleimide, anthracene, and combinations thereof,
wherein said first thermotropic liquid-crystal oligomer molecules are polarizable,
and wherein said first thermotropic liquid-crystal oligomer molecules are characterized by a weight-average molecular weight from about 200 g/mol to about 10,000 g/mol;
(b) optionally, a plurality of second thermotropic liquid-crystal oligomer molecules containing second triggerable reactive end groups,
wherein said second triggerable reactive end groups are selected from the group consisting of hydroxyl, isocyanate, blocked isocyanate, acrylate, epoxide, amine, vinyl, ester, thiol, conjugated diene, substituted alkene, furan, maleimide, anthracene, and combinations thereof,
wherein said second thermotropic liquid-crystal oligomer molecules are polarizable,
and wherein said second triggerable reactive end groups are capable of reacting with said first triggerable reactive end groups; and
(c) optionally, a reactive coupling agent capable of reacting with said first triggerable reactive end groups.
2. The oligomer composition of claim 1 , wherein said first triggerable reactive end groups are reversible end groups selected from conjugated diene, substituted alkene, thiol, furan, maleimide, or a combination thereof.
3. The oligomer composition of claim 1 , wherein said first thermotropic liquid-crystal oligomer molecules further contain first triggerable reactive main-chain pendant groups.
4. The oligomer composition of claim 3 , wherein said first triggerable reactive main-chain pendant groups are selected from the group consisting of hydroxyl, isocyanate, blocked isocyanate, acrylate, epoxide, amine, vinyl, ester, thiol, conjugated diene, substituted alkene, furan, maleimide, anthracene, and combinations thereof.
5. The oligomer composition of claim 1 , wherein said second thermotropic liquid-crystal oligomer molecules are present in said oligomer composition.
6. The oligomer composition of claim 1 , wherein said reactive coupling agent is present in said oligomer composition.
7. The oligomer composition of claim 6 , wherein said reactive coupling agent is mesogenic.