Block Copolymers BCPs in thin films Phenomena Block

Block Copolymers (BCPs) in thin films Phenomena: Block copolymer (BCPs) in thin films with long range selflateral order, assembly and so on….

Block Copolymers (BCPs) in thin films Physics: We consider aspects of segmental interactions, interfacial interaction s,

Block Copolymers (BCPs) in thin films Physics: surface We consider aspects of energy Entropy . . …

1. Morphologies of Block Copolymers Mean Field theory!!! Frank S. Bates, Annu. Rev. Phys. Chem. 1990. 41. 525 -57

1. Morphologies of Block Copolymers � 1. 1 Effect of confinement: � • Symmetric/asymmetric wetting Surface induced ordering P. F. Green, R. Limary, Advances in Clloid and Interface Science 94, 53 (2001)

1. Morphologies of Block Copolymers 1. 2 Surface Energy A—higher interfacial energy with the interface as it increases its fraction; B---lower interfacial energy with interface as it decrease its fraction. Commensurability---On one hand, the total energy is lowest; on the other, the amount of each component is fixed. Together they determine the copolymer structures. E. Huang, S. Pruzinsky, T. P. Russell, J. Mays, C. J. Hawker, Macromolecules 32, 5299(1999)

1. Morphologies of Block Copolymers 1. 3 Heterogeneous Surfaces The strength and lateral distribution of interfacial interactions can direct the BCP morphologies in thin films. J. Heier, et. al. Macromolecules, 30, 6610 (1997)

2. Nanopatterning from BCP Thin Films • Perfect candidates as templates and scaffolds for the fabrication of nanostructured materials. • Top down approaches are coupled with a bottom up approach, to obtain multi length scales control over the ordering and spatial location of nanoscopic elements for device fabrication.

2. Nanopatterning from BCP Thin Films 2. 1 zone casting A. Tracz, et. al. Journal of the American Chemical Society 125, 1682 (2003)

2. Nanopatterning from BCP Thin Films 2. 2 Solvent Annealing The preparation of BCP thin films under various solvent evaporation conditions is an effective way to manipulate the orientation and lateral ordering of BCP microdomains in thin films. S. H. Kim, et. al. Advanced Materials 16, 226 (2004)

2. Nanopatterning from BCP Thin Films 2. 3 Optical Alignment Directionally selective light excitation, using linearly polarized light of photoisomerizable molecules in a liquid-crystalline polymer produced patterned, oriented microdomains in the films. K. Ichimura, Chemical Reviews 100, 1847 (2000)

2. Nanopatterning from BCP Thin Films 2. 4 Shearing BCPs in bulk can easily be aligned by mechanical shear. D. E. Angelescu, et. al. Advanced Materials 16, 1736 (2004)

3. Applications of Nanopatterned BCP Thin Films 3. 1 Nanoporous Membrane for Filtration of Viruses Narrow distribution! High flux! S. Y. Yang, et. al. Advanced Materials 18, 709 (2006)

3. Applications of Nanopatterned BCP Thin Films 3. 2 Incorporation of Nanocrystals and Nanoreactors Nice little workshop for nanoparticles.

3. Applications of Nanopatterned BCP Thin Films 3. 3 Planar Optical Waveguides A. Schematic diagram of the OWS setup based on the Kretschmann configuration, and of the idealized field distribution of several guided modes in the waveguiding layer. B. Schematic diagram of a thin film of PS-b-PMMA/PMMA homopolymer mixture with PMMA microdomains aligned normal to the substrate. D. H. Kim, et. al. Advanced Materials 17, 2442 (2005)

3. Applications of Nanopatterned BCP Thin Films 3. 4 Templated Growth of Nanowires A. An asymmetric diblock copolymer annealed above the glass transition temperature of the copolymer between two electrodes under an applied electric field, forming a hexagonal array of cylinders orientedofnormal to the film B. After removal the minor surface. component, a nanoporous film is formed. C. By electrodepostion, nanowires can be grown in the porous template, forming an array of nanowires in a polymer matrix. T. Thurn-Albrecht, et. al. Science 290, 2126 (2000)