Microcellular materials with stress-activated pores exhibiting opto-mechanical properties and their use as sensors

Patent metadata

Field	Value
Publication number	US-11559928-B2
Application number	US-202016795930-A
Country	US
Kind code	B2
Filing date	Feb 20, 2020
Priority date	Feb 28, 2019
Publication date	Jan 24, 2023
Grant date	Jan 24, 2023

Abstract

Materials that exhibit stress-induced porosity, and methods of making and using the same, are described.

First claim

What is claimed is:

1. An article comprising a foam material comprising a polymer, wherein the article exhibits stress-induced reversible porosity characterized by an affine change in pore size after applying a stress; and
wherein the polymer comprises a block copolymer elastomer.

2. The article of claim 1 , wherein the polymer comprises a physically or chemically cross-linked structure.

3. The article of claim 1 , wherein the polymer comprises poly(styrene-ethylene/butylene-styrene) (SEBS).

4. The article of claim 1 , wherein the polymer comprises poly(styrene-butadiene-styrene) (SBS).

5. The article of claim 1 , wherein the polymer comprises thermoplastic polyurethane (TPU).

6. The article of claim 1 , wherein the polymer is saturated with CO 2 .

7. The article of claim 1 , wherein the article is fabricated by casting a film of the polymer, placing the film in a high-pressure vessel with CO 2 for a first period of time, rapidly depressurizing the film, temperature quenching the film in water for a second period of time, and stabilizing the foam material in a water bath.

8. The article of claim 1 , wherein the foam material has a thickness between 0.05 mm to 2 mm.

9. The article of claim 1 , wherein the article is homogeneous.

10. The article of claim 1 , wherein the article is transparent.

11. The article of claim 1 , wherein the article is opaque.

12. The article of claim 1 , wherein the article has pores having an average size of about 10 μm or less.

13. The article of claim 1 , wherein the article has pores having an average size of about 5 μm or less.

14. The article of claim 1 , wherein the article exhibits a non- recoverable porosity as a result of an applied load.

15. The article of claim 1 , wherein the article is a homogenous, closed-cell porous structure.

16. The article of claim 1 , wherein the article exhibits an ability to be re-foamed through ten stretch cycles without use of a pore forming solvent.

17. The article of claim 1 , wherein thermal activation triggers a pore reversion in the article characterized by a volumetric recovery and an opaque-to-transparent transition (OTT) behavior.

18. The article of claim 1 , wherein exposure to chemical vapors triggers a pore reversion in the article characterized by a volumetric recovery and an opaque-to-transparent transition (OTT) behavior.

19. The article of claim 1 , wherein the article has an average pore size of 1.4±0.7 μm and a pore density of 1.7×10 9 pores/cm 3 .

20. The article of claim 19 , wherein the polymer comprises poly(styrene-ethylene/butylene-styrene) (SEBS).

21. The article of claim 1 , wherein the article has an average pore size of 5.4±3.4 μm and a pore density of 0.7×10 9 pores/cm 3 .

22. The article of claim 21 , wherein the polymer comprises poly(styrene-ethylene/butylene-styrene) (SEBS).

23. The article of claim 1 , wherein the article has an average pore size of 4.9±4.1 μm and a pore density of 11.5×10 9 pores/cm 3 .

24. The article of claim 23 , wherein the polymer comprises poly(styrene-ethylene/butylene-styrene) (SEBS).

25. The article of claim 1 , wherein the article has an average pore size of 4.4±2.8 μm and a pore density of 2.1×10 9 pores/cm 3 .

26. The article of claim 25 , wherein the polymer comprises poly(styrene-ethylene/butylene-styrene) (SEBS).

27. The article of claim 1 , wherein the polymer consists of poly(styrene-ethylene/butylene-styrene) (SEBS).

28. An article comprising a foam material comprising a polymer, wherein the article exhibits a stress-induced opaque-to-transparent transition characterized by an affine change in pore size after applying a stress; and
wherein the polymer comprises a block copolymer elastomer.

29. The article of claim 28 , wherein the polymer consists of poly(styrene-ethylene/butylene-styrene) (SEBS).

Assignees

• Univ Toledo

Inventors

• Rizvi Syed Reza
• Rasel Sheikh
• Bhuiyan Md Emran Hossain
• Namdari Navid
• Halim Bilal Nizar Abdul

Classifications

• B29K2105/046

  with closed cells · CPC title

• B29K2009/06

  SB polymers, i.e. butadiene-styrene polymers · CPC title

• B29C43/22

  of articles of indefinite length · CPC title

• B29C44/3403

  Foaming under special conditions, e.g. in sub-atmospheric pressure, in or on a liquid · CPC title

• B29K2995/0025

  Opaque · CPC title