Molecularly engineered high thermal conductivity polymers and methods for making the same

Patent metadata

Field	Value
Publication number	US-10696885-B2
Application number	US-201816002809-A
Country	US
Kind code	B2
Filing date	Jun 7, 2018
Priority date	Jun 9, 2017
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Methods of increasing thermal conductivity of a bulk polymer are provided. The methods include contacting a bulk polyelectrolyte polymer comprising an ionizable repeating pendant group with an aqueous liquid having a pH that ionizes the pendant group and isotropically extend the polyelectrolyte polymer to an extended non-globular chain conformation. The polyelectrolyte polymer so treated thus exhibits a thermal conductivity of greater than or equal to about 0.6 W/m·K and optionally greater than or equal to about 1 W/m·K. In other aspects, the present disclosure provides a high thermal conductivity material comprising a bulk polyelectrolyte polymer bearing a repeating charged group and having an extended non-globular chain conformation and that exhibits a thermal conductivity of greater than or equal to about 0.6 W/m·K and optionally greater than or equal to about 1 W/m·K. The high thermal conductivity material may be used in electronic devices, including as housings/encapsulation and thermal interfaces.

First claim

What is claimed is:

1. A method of increasing thermal conductivity of a bulk polymer comprising:
contacting a bulk polyelectrolyte polymer that is a polyanion comprising a repeating ionizable pendant group with an aqueous liquid having a pH greater than 7 that ionizes the pendant group and isotropically extends the polyelectrolyte polymer to an extended non-globular chain conformation so that the polyelectrolyte polymer exhibits a thermal conductivity of greater than or equal to about 0.6 W/m·K.

2. The method of claim 1 , wherein the contacting with the aqueous liquid having the pH increases a thermal conductivity of the bulk polyelectrolyte polymer by at least four times greater than an initial thermal conductivity prior to the contacting.

3. The method of claim 1 , wherein the contacting further comprises combining the bulk polyelectrolyte polymer with the aqueous liquid and at least one base to form an admixture.

4. The method of claim 3 , wherein the at least one base is added to the aqueous liquid to increase pH to greater than or equal to about 12.

5. The method of claim 3 , further comprising spin casting the admixture onto a substrate to form a solid film of the polyelectrolyte polymer having the extended non-globular chain conformation having the thermal conductivity of greater than or equal to about 1 W/m·K.

6. The method of claim 5 , wherein the solid film has a thickness of greater than or equal to about 10 nm to less than or equal to about 35 nm.

7. The method of claim 3 , further comprising blade coating the admixture onto a substrate to form a solid film of the polyelectrolyte polymer having the extended non-globular chain conformation with the thermal conductivity of greater than or equal to about 0.6 W/m·K.

8. The method of claim 7 , wherein the solid film has a thickness of greater than or equal to about 1.5 μm to less than or equal to about 6 μm.

9. The method of claim 1 , wherein the bulk polyelectrolyte polymer comprises polyacrylic acid (PAA).

10. The method of claim 1 , wherein the bulk polyelectrolyte polymer is present at greater than or equal to about 0.5% by weight to less than or equal to about 2% by weight in the aqueous liquid.

11. A method of increasing thermal conductivity of a bulk polymer comprising:
contacting a bulk polyelectrolyte polymer comprising a repeating ionizable pendant group with an aqueous liquid having a pH that ionizes the pendant group and isotropically extends the polyelectrolyte polymer to an extended non-globular chain conformation so that the polyelectrolyte polymer exhibits a thermal conductivity of greater than or equal to about 0.6 W/m·K and the contacting occurs until a relative viscosity (η r ) of the bulk polyelectrolyte polymer to water is greater than or equal to about 6.5.

12. The method of claim 11 , wherein the contacting further comprises combining the bulk polyelectrolyte polymer with the aqueous liquid and at least one acid or base to form an admixture.

13. The method of claim 12 , wherein the bulk polyelectrolyte polymer is a polyanion and at least one base is added to the aqueous liquid to increase pH to greater than or equal to about 12.

14. The method of claim 12 , further comprising spin casting the admixture onto a substrate to form a solid film of the polyelectrolyte polymer having the extended non-globular chain conformation having the thermal conductivity of greater than or equal to about 1 W/m·K.

15. The method of claim 11 , wherein further comprising blade coating the admixture onto a substrate to form a solid film of the polyelectrolyte polymer having the extended non-globular chain conformation with the thermal conductivity of greater than or equal to about 0.6 W/m·K.

16. The method of claim 11 , wherein the bulk polyelectrolyte polymer comprises polyacrylic acid (PAA).

17. The method of claim 11 , wherein the bulk polyelectrolyte polymer is present at greater than or equal to about 0.5% by weight to less than or equal to about 2% by weight in the aqueous liquid.

18. A method of increasing thermal conductivity of a bulk polymer comprising:
contacting a bulk polyelectrolyte polymer that is a polycation comprising a repeating ionizable pendant group with an aqueous liquid having a pH of less than 7 that ionizes the pendant group and isotropically extends the polyelectrolyte polymer to an extended non-globular chain conformation so that the polyelectrolyte polymer exhibits a thermal conductivity of greater than or equal to about 0.6 W/m·K, wherein the polycation is selected from the group consisting of: arginine, asparagine, aspartic acid, glutamic acid, glutamine, histidine, lysine, serine, threonine, and/or tyrosine, and combinations thereof.

19. The method of claim 18 , wherein the contacting further comprises combining the bulk polyelectrolyte polymer with the aqueous liquid and at least one acid to form an admixture.

20. The method of claim 18 , wherein at least one acid is added to the aqueous liquid to reduce pH to less than or equal to about 5.

Assignees

• Univ Michigan Regents

Inventors

• Kim Jinsang
• Li Chen
• Shanker Apoorv
• Pipe Kevin
• Kim Gun-Ho

Classifications

• C09D139/06

  Homopolymers or copolymers of N-vinyl-pyrrolidones · CPC title

• C09D133/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• B29C2071/022

  Annealing · CPC title

• C08J2333/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title