Porous polymeric membrane with high void volume
Membranes comprising first and second microporous surfaces, and, a porous bulk between the surfaces, the bulk comprising first and second regions; the first region comprising a first set of pores having outer rims, and having controlled pore size, and a second set of pores connecting the outer rims of the first set of pores, the second set of pores having a controlled pore size, and a polymer matrix supporting the first set of pores; the second region comprising a third set of pores having outer rims, and having a controlled pore size, and a fourth set of pores connecting the outer rims of the third set of pores, the fourth set of pores having a controlled pore size, and a polymer matrix supporting the third set of pores; and methods of making and using the membranes, are disclosed.
1. A microporous membrane comprising
(A) a single integral layer comprising
(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 a first region, a second region, and at least one additional region located between the first region and the 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, 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 first polymer matrix supporting the first set of pores, wherein the first controlled pore size is greater than the second controlled pore size, and the first controlled pore size is about 540 to about 620 nm;
(b) the second region comprising a third set of hexagonally packed pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the third set of pores having a third controlled pore size, and a fourth set of pores connecting the outer rims of the third set of pores, the fourth set of pores having a fourth controlled pore size, and a second polymer matrix supporting the third set of pores, wherein the third controlled pore size is greater than the fourth controlled pore size, and wherein the third controlled pore size is about 280 nm to about 340 nm; and,
(c) the additional region comprising a fifth set of hexagonally packed pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the fifth set of pores having a fifth controlled pore size, and a sixth set of pores connecting the outer rims of the fifth set of pores, the sixth set of pores having a sixth controlled pore size, and a third polymer matrix supporting the fifth set of pores, wherein the fifth controlled pore size is greater than the sixth controlled pore size, and wherein the fifth controlled pore size is about 160 nm to about 180 nm, and wherein the first polymer matrix, the second polymer matrix, and the third polymer matrix, each comprise polyethersulfone or each comprise polyacrylonitrile or each comprise polyvinylidene fluoride;
wherein the microporous membrane has a void volume fraction of about 66% to 74%.
2. A method of filtering a fluid, the method comprising passing the fluid through the membrane of claim 1 .
3. A method of making a microporous membrane, the method comprising
(A) a single integral layer comprising
(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 a first region, a second region, and at least one additional region located between the first region and the 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, 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 first polymer matrix supporting the first set of pores, wherein the first controlled pore size is greater than the second controlled pore size, and the first controlled pore size is about 540 to about 620 nm;
(b) the second region comprising a third set of hexagonally packed pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the third set of pores having a third controlled pore size, and a fourth set of pores connecting the outer rims of the third set of pores, the fourth set of pores having a fourth controlled pore size, and a second polymer matrix supporting the third set of pores, wherein the third controlled pore size is about 280 nm to about 340 nm; and,
(c) the additional region comprising a fifth set of hexagonally packed pores having outer rims, prepared by removing introduced dissolvable silica nanoparticles, the fifth set of pores having a fifth controlled pore size, and a sixth set of pores connecting the outer rims of the fifth set of pores, the sixth set of pores having a sixth controlled pore size, and a third polymer matrix supporting the fifth set of pores, wherein the fifth controlled pore size is greater than the sixth controlled pore size, and wherein the fifth controlled pore size is about 160 nm to about 180 nm, and wherein the first polymer matrix, the second polymer matrix, and the third polymer matrix, each comprise polyethersulfone or each comprise polyacrylonitrile or each comprise polyvinylidene fluoride;
wherein the microporous membrane has a void volume fraction of about 66% to 74%;
the method comprising:
(a) casting a first dissolvable silica nanoparticle-containing polymer solution onto a substrate, wherein dissolvable silica nanoparticles in the first dissolvable silica nanoparticle-containing polymer solution contact each other at an interface, wherein the first dissolvable silica nanoparticle-containing polymer solution comprises polyethersulfone or polyacrylonitrile or polyvinylidene fluoride;
(b) casting a second dissolvable silica nanoparticle-containing polymer solution onto the cast solution of
(a), wherein dissolvable silica nanoparticles in the second dissolvable silica nanoparticle-containing polymer solution contact each other at an interface, wherein the second dissolvable silica nanoparticle-containing polymer solution includes polyethersulfone or polyacrylonitrile or polyvinylidene fluoride;
(c) casting a third dissolvable silica nanoparticle-containing polymer solution onto the cast solution of (b), wherein dissolvable silica nanoparticles in the third dissolvable silica nanoparticle-containing polymer solution contact each other at an interface, wherein the third dissolvable silica nanoparticle-containing polymer solution includes polyethersulfone or polyacrylonitrile or polyvinylidene fluoride;
(d) carrying out phase inversion and obtaining a membrane;
(e) dissolving the nanoparticles and obtaining a nanoparticle-depleted membrane; and
(f) washing the nanoparticle-depleted membrane.