Isoporous mesoporous asymmetric block copolymer materials with macrovoids and method of making the same
A mesoporous isoporous asymmetric material includes at least one diblock or multiblock copolymer, wherein the material has a transition layer having a thickness of at least 300 nm and a low macrovoid density, and the material has a sub-structure adjacent to said transition layer and said sub-structure comprises a high macrovoid density. A method for producing mesoporous isoporous asymmetric materials having macrovoids can include: dissolving at least one diblock or multiblock copolymer in a solution, the solution having one or more solvents and one or more nonsolvents, to form a polymer solution; dispensing the polymer solution onto a substrate or mold, or through a die or template; removing at least a portion of solvent and/or nonsolvent from the polymer solution to form a concentrated polymer solution; and exposing the concentrated polymer solution to a nonsolvent causing precipitation of at least a portion of the polymer from the concentrated polymer solution.
1. A mesoporous isoporous asymmetric material comprising a diblock copolymer,
a. a mesoporous isoporous skin layer;
b. a substructure layer having a thickness of about 1 micron to about 500 microns and a high macrovoid density of at least 10 6 macrovoids/m 2 ; and
c. a transition layer between the mesoporous is oporous skin layer and the substructure layer, the transition layer having a thickness of at least 300 nm and a low macrovoid density, wherein the low macrovoid density is defined by the transition layer having a ratio of macrovoids to mesopores of at most 2×10 −9 ;
wherein a macrovoid is a void with at least one characteristic length greater than 0.5 microns.
2. The mesoporous isoporous asymmetric material of claim 1 , wherein the material is freestanding and exhibits a dried density of less than 0.26 g/cm 3 ; and wherein the material is dried by heating in an oven at 65° C. for 48 hours.
3. The mesoporous isoporous asymmetric material of claim 2 , wherein the material exhibits a dried density of less than 0.22 g/cm 3 .
4. The mesoporous isoporous asymmetric material of claim 1 wherein the transition layer has a thickness of at least about 500 nm.
5. The mesoporous isoporous asymmetric material of claim 1 , wherein the material exhibits a radius of curvature to fracture down to about 0.05 inches without cracking; and wherein the radius of curvature to fracture is measured by curving about 1 cm length of the material in a freestanding wet state around a rod or tube of known diameter.
6. The mesoporous isoporous asymmetric material of claim 1 , wherein said macrovoids comprise at least one of
a. finger-like macrovoids consisting of void structures with at least two dimensions greater than 0.5 microns and an aspect ratio greater than 3;
b. spherical macrovoids consisting of approximately spherioidal void structures with approximate diameter of at least 0.5 microns; and
c. tear-like macrovoids consisting of void structures with at least two distinctly different characteristic lengths and at least two characteristic lengths greater than 0.5 microns.
7. The mesoporous isoporous asymmetric material of claim 1 , wherein the mesoporous isoporous skin layer comprises a pore density of 10 13 pores/m 2 to 10 14 pores/m 2 .