Self-assembly of block copolymers on topographically patterned polymeric substrates
Highly-ordered block copolymer films are prepared by a method that includes forming a polymeric replica of a topographically patterned crystalline surface, forming a block copolymer film on the topographically patterned surface of the polymeric replica, and annealing the block copolymer film. The resulting structures can be used in a variety of different applications, including the fabrication of high density data storage media. The ability to use flexible polymers to form the polymeric replica facilitates industrial-scale processes utilizing the highly-ordered block copolymer films.
1. A layered article, comprising:
a polymer layer comprising a topographically patterned surface formed by contact with a topographically patterned surface of a single crystal substrate; wherein the topographically patterned surface of the single crystal substrate is a substantially planar surface at least one degree removed from any crystallographic plane of the single crystal substrate; and
a block copolymer film comprising a surface in contact with the patterned surface of the polymer layer; wherein the block copolymer film consists of a block copolymer selected from the group consisting of polystyrene-b-poly(4-vinylpyridine)s, polystyrene-b-poly(2-vinylpyridine)s, and polystyrene-b-poly(ethylene oxide)s wherein the block copolymer film is an annealed block copolymer film and the annealed block copolymer film comprises a hexagonal array of cylindrical microdomains.
2. The layered article of claim 1 , wherein the hexagonal array of cylindrical microdomains exhibits an orientation order of at least 0.9 over an area of at least 1 centimeter 2 .
3. The layered article of claim 1 , wherein the hexagonal array of cylindrical microdomains exhibits an orientation order greater than that of the topographically patterned surface of the polymer layer.
4. The layered article of claim 1 , wherein the cylindrical microdomains are separated by a nearest-neighbor distance of about 10 to about 100 nanometers.
5. The layered article of claim 1 , wherein the topographically patterned surface of the polymer layer comprises a sawtooth pattern characterized by a peak-to-peak separation, L R ; wherein the block copolymer film comprises a hexagonal array of cylindrical microdomains characterized by a nearest-neighbor microdomain separation, L BCP ; and wherein L R /L BCP has a value of about 1 to about 10.
6. The layered article of claim 1 , wherein the topographically patterned surface of the polymer layer comprises a sawtooth pattern characterized by a period of about 24 to about 200 nanometers and an amplitude of about 3 to about 20 nanometers.
7. The layered article of claim 1 , wherein the topographically patterned surface of the polymer layer comprises a grooved pattern characterized by a groove depth of about 3 to about 20 nanometers and a groove-to-groove separation of about 24 to about 200 nanometers.
8. The layered article of claim 1 , wherein the block copolymer film is an annealed and solvent-reconstructed block copolymer film.
9. The layered article of claim 1 ,
wherein the block copolymer film comprises a polystyrene-b-poly(ethylene oxide);
wherein the polystyrene-b-poly(ethylene oxide) comprises a polystyrene block having a number average molecular weight of 6,000 to 30,000 atomic mass units and a poly(ethylene oxide) block having a number average molecular weight of 2,000 to 10,000 atomic mass units; and
wherein a ratio of the number average molecular weight of the polystyrene block to the number average molecular weight of the poly(ethylene oxide) block is 2:1 to 6:1.
10. The layered article of claim 1 , wherein the block copolymer film has a thickness of about 10 to about 100 nanometers.