Porous polymeric membrane with high void volume

Patent metadata

Field	Value
Publication number	US-9776142-B2
Application number	US-201414193745-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Feb 28, 2014
Publication date	Oct 3, 2017
Grant date	Oct 3, 2017

Abstract

Microporous membranes comprising a single integral layer having first and second microporous surfaces; and, a porous bulk between the microporous surfaces, wherein the bulk comprises at least a first region and a second region; the first region comprising a first set of pores having outer rims, prepared by removing introduced silica dissolvable nanoparticles, the first set of pores having a first controlled pore size, and a second set of pores connecting the outer rims, the second set of pores having a second controlled pore size, and a polymer matrix supporting the first set of pores, wherein the first controlled pore size is greater than the second controlled pore size; the second region comprising a third set of pores prepared by phase inversion, the third set of pores having a third controlled pore size, filters including the membranes, and methods of making and using the membranes, are disclosed.

First claim

The invention claimed is:

1. A microporous membrane comprising
(A) a single integral layer having
(i) a first microporous surface;
(ii) a second microporous surface; and,
(iii) a porous bulk between the first microporous surface and the second microporous surface, wherein the bulk comprises at least a first region and a second region;
(a) the first region comprising a first set of hexagonally packed pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the first set of pores having a first controlled pore size of about 310 nm to about 360 nm, and a second set of pores connecting the outer rims of the first set of pores, the second set of pores having a second controlled pore size, and a polyethersulfone polymer matrix supporting the first set of pores, wherein the first controlled pore size is greater than the second controlled pore size, and wherein the first region has a void volume fraction of about 66% to 74%;
(b) the second region comprising a polyethersulfone polymer and a third set of pores prepared by phase inversion, the third set of pores having a third controlled pore size wherein the third controlled pore size is at least about 10% less than the first controlled pore size, and
(c) at least one additional region arranged between the first region and the second region, the additional region comprising a polyethersulfone polymer and at least a fourth set of pores comprising hexagonally packed pores having a fourth controlled pore size of about 520 nm to about 630 nm, wherein the fourth set of pores have outer rims, prepared by removing introduced dissolvable silica nanoparticles, and the additional region further comprises a fifth set of pores connecting the outer rims of the fourth set of pores, the fifth set of pores having a fifth controlled pore size, and a polymer matrix comprising the polyethersulfone polymer of the at least one additional region supporting the fourth set of pores, wherein the fourth controlled pore size is greater than the fifth controlled pore size, and wherein the additional region has a void volume fraction of about 66% to 74%;
wherein the third controlled pore size is greater than the fifth controlled pore size, the fourth controlled pore size is greater than the first controlled pore size and the second controlled pore size, and the fifth controlled pore size is less than the first controlled pore size and greater than the second controlled pore size.

2. The membrane of claim 1 , wherein the third set of pores provides a symmetric pore structure.

3. The membrane of claim 1 , wherein the third set of pores provides an asymmetric pore structure.

4. A method of filtering a fluid, the method comprising passing the fluid through the membrane of claim 1 .

5. A method of preparing a microporous membrane comprising
(A) a single integral layer having
(i) a first microporous surface;
(ii) a second microporous surface; and,
(iii) a porous bulk between the first microporous surface and the second microporous surface, wherein the bulk comprises at least a first region and a second region;
(a) the first region comprising a first set of pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the first set of pores having a first controlled pore size of about 310 nm to about 360 nm, and a second set of pores connecting the outer rims of the first set of pores, the second set of pores having a second controlled pore size, and a polyethersulfone polymer matrix supporting the first set of pores, wherein the first controlled pore size is greater than the second controlled pore size,
 and wherein the first region has a void volume fraction of about 66% to 74%;
(b) the second region comprising a polyethersulfone polymer and a third set of pores prepared by phase inversion, the third set of pores having a third controlled pore size wherein the third controlled pore size is at least about 10% less than, or at least about 10% greater than, the first controlled pore size,
 and
(c) at least one additional region arranged between the first region and the second region, the additional region comprising a polyethersulfone polymer and at least a fourth set of pores comprising hexagonally packed pores having a fourth controlled pore size of about 520 nm to about 630 nm, wherein the fourth set of pores have outer rims, prepared by removing introduced dissolvable silica nanoparticles, and the additional region further comprises a fifth set of pores connecting the outer rims of the fourth set of pores, the fifth set of pores having a fifth controlled pore size, and a polymer matrix comprising the polyethersulfone polymer of the at least one additional region supporting the fourth set of pores, wherein the fourth controlled pore size is greater than the fifth controlled pore size, and wherein the additional region has a void volume fraction of about 66% to 74%;
wherein the third controlled pore size is greater than the fifth controlled pore size, the fourth controlled pore size is greater than the first controlled pore size and the second controlled pore size, and the fifth controlled pore size is less than the first controlled pore size and greater than the second controlled pore size;
the method comprising:

(a) casting a dissolvable silica nanoparticle-containing polyethersulfone polymer solution onto a substrate or onto a film on the substrate;
(a 1 ) casting an additional dissolvable silica nanoparticle-containing polyethersulfone polymer solution on the coated substrate of (a);
(b) casting a polyethersulfone polymer solution lacking dissolvable silica nanoparticles onto the coated substrate of (a 1 ), carrying out phase inversion and obtaining a membrane;
(c) dissolving the nanoparticles and obtaining a nanoparticle-depleted membrane comprising the first region, the second region, and the additional region; and,
(d) washing the nanoparticle-depleted membrane.

6. A method of filtering a fluid, the method comprising passing the fluid through the membrane of claim 2 .

7. A method of filtering a fluid, the method comprising passing the fluid through the membrane of claim 3 .

8. The microporous membrane of claim 1 , wherein the polymer of the polymer matrix of the first region, and the polymer of the second region, and the polymer of the polymer matrix of the at least one additional region, each comprise polysulfone.

Assignees

• Pall Corp

Inventors

• Wu Xiaosong
• David Yolando
• Harton Shane Edward
• Singh Amarnauth

Classifications

• B01D71/06

  Organic material · CPC title

• B01D69/105

  Support pretreatment · CPC title

• B01D69/02 Primary

  characterised by their properties · CPC title

• B01D2323/18

  Pore-control agents or pore formers · CPC title

• B01D2323/21

  Fillers · CPC title