Abstract I Contents IV List of Tables VIII Figures Captions IX Chapter 1 Introduction 1 1.1 Nanopatterning by Top-down Approach 2 1.1-1 Soft-lithography 2 1.1-2 Scanning Probe Lithography 3 1.1-3 Electron-lithography 4 1.2 Nanopatterning by Bottom-up Approach 4 1.2-1 Self-assembly 5 1.2-2 Self-assembly of Block Copolymers 7 1.2-3 Nanopatterning by Self-assembly of Block Copolymer 8 1.2-3-1 Solution Casting 10 1.2-3-2 Shear-induced Orientation 10 1.2-3-3 Electric Field-induced Orientation 11 1.2-3-4 Surface-induced Orientation 12 1.2-3-5 Patterned Substrate-induced Orientation 12 1.2-3-6 Temperature Gradient-induced Orientation 13 1.2-3-7 Graphoepitaxy-induced Orientation 14 1.2-3-8 Crystallizable Solvent-induced Orientation 14 1.2-3-9 Photo-induced Orientation 15 1.3 Degradable Copolymers 16 1.3-1 PB or PI contained Degradable Block Copolymers 16 1.3-2 PMMA Contained Degradable Copolymers 17 1.3-3 PLA Contained Degradable Block Copolymers 17 1.4 Nanotemplation from Block Copolymers 18 1.4-1 Nanotemplation from Organic-organometallic Block Copolymers 19 1.4-2 Nanotemplation from Amphiphilic Block Copolymers 20 1.4-3 Nanotemplation from Degradable Copolymers 22 1.5 Inorganic Nanohelices and Corresponding Nanocomposites 24 1.5-1 Chemical Vapor Deposition 24 1.5-2 Vapor-solid Growth Process 25 1.5-3. Glancing Angle Deposition (GLAD) 26 1.5-4 Self-assembly of Chiral Surfactant/Inorganic Precursors 27 1.5-5 Self-assembly of Achiral Surfactant/Inorganic Precursors in Nanoconfinement 29 Chapter 2 Objectives 62 Chapter 3 Experimental 67 3.1 Materials 67 3.2 Sample Preparation 68 3.3 Instruments 71 Chapter 4 Results and Discussion 77 4.1 Oriented Lamellar PS-PLLA Thin Films Induced by Crystallizable Solvents .77 4.1-1 Morphologies of PS-PLLA Thin Films 77 4.1-2 Oriented PS130-PLLA106 Nanostructures from BA 78 4.1-3 Lattice Matching Effect for PS130-PLLA106 Nanostructures 80 4.1-4 PS130-PLLA106 Morphology via Directional Eutectic Solidification 80 4.1-5 PS36-PLLA32 Morphology via Directional Eutectic Solidification 81 4.1-6 Crystallization-induced Oriented PS36-PLLA32 Nanostructures 82 4.1-7 Origins of Induced Orientation 84 4.1-8 Nanopatterned Templates by Hydrolysis 87 4.2 Oriented Cylindrical PS-PLLA Thin Films Induced by Solution Casting 87 4.2-1 Phase-separated Morphology 88 4.2-2 Induced Orientation of PS-PLLA Thin Films 89 4.2-3 Evaporation Rate and Solubility Effects 90 4.2-4 Molecular Weight Effect 94 4.2-5 Spin Coating versus Solution Casting 95 4.2-6 Substrate Effect 97 4.2-7 Origins of Induced Orientation 99 4.2-8 Nanopatterned Templates by Hydrolysis 105 4.3 Helical Nanocomposites and Nanohelices from Chiral Degradable PS-PLLA 106 4.3-1 Identification of Nanohelical Structure Phase 108 4.3-2 Helical Nanocomposites 110 4.3-3 Inorganic Nanohelices 112 4.3-4 Problems for Low-modulus Inorganic Nanohelices 114 4.3-5 Potential Applications 116 Chapter 5 Conclusions 137 Chapter 6 References 140 Publications 148 List of Tables Table 1 Varieties of synthesized PS-PLLA and PS-PLA block copolymers 75 Table 2 The selectivity and vapor pressure of solvents 118 Figure Captions Figure 1-1. (a) Topographic nanopattern. (b) Chemical nanopattern. 31 Figure 1-2. Photolithography. 31 Figure 1-3. Soft-lithography. 32 Figure 1-4. (a) Scanning probe lithography is electrically conducting SPM (or STM) tip that is operated in air to anodically oxidize selected regions of a sample surface. (b) After selective etching, the topographic nanopattern was obtained. 32 Figure 1-5. (a) Schematic of magnetic nanoarrays fabrication process. (b)SEM image of magnetic nanoarrays.. 33 Figure 1-6. Examples of static self-assembly. (a) Crystal structure of a ribosome. (b) Self-assembled peptideamphiphile nanofibers. (c) An array of millimeter sized polymeric plates assembled at a water/perfluorodecalin interface by capillary interactions. (d) Thin film of a nematic liquid crystal on an isotropic substrate. (e) Micrometersized metallic polyhedra folded from planar substrates. (f) A three-dimensional aggregate of micrometer plates assembled by capillary forces. 34 Figure 1-7. Examples of dynamic self-assembly. (a) An optical micrograph of a cell with fluorescently labeled cytoskeleton and nucleus (b) Reaction-diffusion waves in a Belousov-Zabatinski reaction in a 3.5-inch Petri dish. (c) A simple aggregate of three millimeter-sized, rotating, magnetized disks interacting with one another via vortex-vortex interactions. (d) A school of fish. (e) Concentric rings formed by charged metallic beads 1 mm in diameter rolling in circular paths on a dielectric support. (f) Convection cells formed above a micropatterned metallic support. The distance between the centers of the cells is ~ 2 mm. 35 Figure 1-8. (a) Schematic phase diagram showing the various morphologies adopted by non-crystalline linear diblock copolymer. (b) Schematic of morphologies for linear ABC triblock copolymer. A combination of block sequence (ABC, ACB, BAC), composition and block molecular weights provides an enormous parameter space for the creation of new morphologies. 36 Figure 1-9. SPM phase micrographs of PS-PEO with cylindrical microdomains oriented normal to the film surface are obtained after spin coating onto silicon substrate (a) 25K PS-PEO with a film thickness of 140 nm (b) 90K PS-PEO with a film thickness of 150 nm. 37 Figure 1-10. (a) PS-PEO thin films obtained by spin-coating: SPM phase micrograph of a spin-coated sample, (b) SPM phase micrograph after annealing for 48 hr in the benzene vapor. 37 Figure 1-11. (a) Schematic of the roll-caster used to generate nanoscopically oriented films. Two independent, motorcontrolled, parallel rollers counter-rotate at a constant frequency. The rollers are separated by a micrometer-controlled gap. A viscous block copolymer solution is introduced into the gap region and allowed to undergo microphase separation in the presence of the flow field. After slow evaporation of the solvent an oriented film preferentially forms on the stainless-steel roller.31 (b) Schematic diagram of the nanoscale alignments that can be induced in lamellar block copolymers: perpendicular and parallel. The third principal projection is termed transverse. 38 Figure 1-12. (a) Schematic of shear-alignment. (b) The SPM micrograph of PS-PEP thin film after shear-alignment; the inset shows the Fast Fourier transforms (FFTs). 39 Figure 1-13. Schematic of electric field-induced orientation. (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 oriented normal to the film substrate. (b) After removal of the minor component by UV exposure, a nanoporous film is formed. 40 Figure 1-14. SPM phase micrographs. Micrographs are from thin films of PS-PMMA symmetric diblock copolymer with a random copolymer (red) anchored either. (a) to the substrate only; or (b) to the substrate and air surface. Scale bar, 100 nm. Insets indicate the orientation of the lamellar morphology in the films. 40 Figure 1-15. Schematic representation of the strategy used to create chemically nanopatterned surfaces and investigate the epitaxial assembly of block-copolymer domains. (a) A SAM of PETS was deposited on a silicon wafer. (b) Photoresist was spin-coated on the SAM-covered substrate, and (c) patterned by EUV-IL with alternating lines and spaces of period Ls. (d) The topographic pattern in the photoresist was converted to a chemical pattern on the surface of the SAM by irradiating the sample with soft X-rays in the presence of oxygen. (e) The photoresist was then removed with repeated solvent washes. (f) A symmetric, lamella-forming PS- PMMA copolymer of period Lo was spin-coated onto the patterned SAM surface and (g) annealed, resulting in surface directed block-copolymer morphologies. Chemically modified regions of the surface presented polar groups containing oxygen and were preferentially wetted by the PMMA block, and unmodified regions exhibited neutral wetting behavior by the block copolymer. 41 Figure 1-16. Schematic of cell used to hold polymer sample. The surfaces on either side are exposed to thin sheets of Teflon. Key: (a) front view of the temperature cell and (b) cross-sectional view of the temperature cell at the center. 41 Figure 1-17. SPM micrograph of PS-PVP film on the top of a mesa (spacing = 4.5 μm). 42 Figure 1-18. Diagrams showing structural evolution during the directional eutectic solidification and epitaxial crystallization of the block copolymer from the crystallizable solvent. (a) Homogeneous solution of PS-PE in BA between two glass substrates. (b) Directional solidification forms BA crystals coexisting with a liquid layer of more concentrated polymer. (c) Second directional solidification, showing the eutectic liquid layer transforming into BA crystal (which grows on the pre-eutectic BA crystal) and an ordered lamellar block copolymer. (d) Because of the highly asymmetric composition of the block copolymer and the epitaxial crystallization of the PE in contact with the BA substrate, the flat interfaces of vertically oriented lamellae are unstable, and spontaneously deform in order to achieve a more preferred interfacial curvature and allow epitaxial growth of PE. (e) The layers transform into an array of vertically oriented, pseudohexagonally packed semicrystalline PE cylinders. 43 Figure 1-19. (a) Scheme of LC alignment and microphase-separated structures in the irradiated and un-irradiated area of the block copolymer films. (b) SPM phase micrograph after photo-induced orientation. 44 Figure 1-20. (a) The schematic of process. TEM micrographs of (b) a spherical microdomain monolayer film before RIE. The lighter regions are the PB domains that were degraded and removed by ozone, and the darker backgroundis the PS matrix. (c) Hexagonally ordered arrays of holes in silicon nitride after RIE. (d) SEM micrographs of a partially etched, ozonated monolayer film of spherical microdomains. After the continuous PS matrix at top was taken off, the empty PI domains were exposed (as holes) and appear darker in the micrograph. (e) An SEM micrograph of ordered arrays of holes on silicon nitride. 45 Figure 1-21. FESEM micrograph obtained from a PS-PMMA thin film after removing the PMMA by UV degradation. (a) top view (b) cross-sectional view. 46 Figure 1-22. FESEM micrographs of the degraded PS-PLA fractured surface. The scale bar is 100 nm. 47 Figure 1-23. Tilted SEM micrographs of the fabrication process of Co nanoarrays using PS-PFS thin films. (a) An O2-RIE treated block copolymer thin film on a multilayer of silica, the metallic films and the silicon substrate. (b) Pillars of silicon oxide capped with oxidized PFS after CHF3-RIE. (c) W (tungsten) hard mask on top of a Co layer. (d) Co nanoarrays produced by Ne ion-beam etching. 48 Figure 1-24. (a) TEM micrograph of cross-section of the CdSe/PS-b-P2VP film after annealing at 170 0C for 2 days. (b) Secondary electron SEM micrograph of the surface of a thin film of CdSe/PS-b-P2VP annealed at 170 0C for 2 days taken at 1-kV acceleration voltage. (c) Schematic representation of nanoparticle assembly at the P2VP cylinders. 49 Figure 1-25. SPM height micrographs of micellar thin films: (a) as-cast film; (b) film treated in 0.04 M NaOH(aq). 49 Figure 1-26. Plan-view TEM of cavitated thin film treated with PbAc2(aq) and exposed to H2S(g). 50 Figure 1-27. Pathway to nanostructured materials: (a) diblock copolymer, (b) polygranular cylindrical morphology, (c) macroscopically aligned cylindrical morphology achieved by shear-orientation, (d) removal of minor component to yield nanoporous template, (e) and (f) preparation of nanowires and nanoparticles within the template, respectively, and (g) and (h) removal of template to obtain nanostructured materials. 50 Figure 1-28. TEM micrographs of a spin-coated solution of (a) PPY nanowire and (b) CdS nanoparticles. 51 Figure 1-29. The illustration of pore-filling process. 51 Figure 1-30. Schematic of the process for preparation of the Pd nanoparticles by double gyroid textures. 52 Figure 1-31. TEM micrographs of Pd-loaded gyroid network after reduction in 1-propanol/toluene/Pd(acac)2 for different times at 85 °C: (a) 13, (b) 24, and (c) 48 h. 52 Figure 1-32. Programmable temperature controlled tube furnace.During reaction, the Ar carrier gas was allowed to flow into the tube from both ends and exhaust out from the inner ceramic tube. Iron powder and SiO2/Si mixed powder were loaded in two sample boats located near the center of the furnace right below the Si wafer. CH4 was added into the Ar carrier gas on the left side of the furnace. 53 Figure 1-33. SEM characterization of as-synthesized silicon oxide nanowires. 53 Figure 1-34. SEM micrographs of the as-synthesized ZnO nanobelts, showing nanobelts of sizes 20-60 nm in widths and a large fraction of nanorings and nanohelices. 54 Figure 1-35. SEM micrographs of the as-synthesized ZnO nanobelts with right hand helical nanostructure. The typical width is 30 nm, and pitch distance is rather uniform. 55 Figure 1-36. (a) A schematic model of a nanobelt as viewed parallel to its flat surfaces, displaying the (0001) polar surfaces with a macroscopic dipole moment. (b) Schematic models showing the formation of helical nanostructures by rolling up a nanobelt. 55 Figure 1-37. The helical nanoporous thin film could be fabricated from a GLAD template in the following process: (a) The helical template film is deposited using GLAD. (b) The helical template film is filled with the matrix material. (c) The matrix material is etched back to expose the helical template. (d) The helical template is removed by chemical etching. 56 Figure 1-38. GLAD process. 56 Figure 1-39. (a) A 3-turn SiO2 helical film deposited at α = 85o onto a thin NiCu coated substrate acts as the template for the fabrication of a gold helical nanoporous thin films. (b) After plating, etch-back, and etch-removal of the template, helical pores are clearly visible. 57 Figure 1-40. Schematic of the interaction between the head group of C14-L-AlaS and amino group. 57 Figure 1-41. SEM micrographs of silica helices synthesized with various stirring rates. (a) 200 rpm, (b) 400 rpm, (c) 600 rpm, (d) 800 rpm, and (e) 1200 rpm. 58 Figure 1-42. TEM micrographs of the silica helices shown in Figure 1-35 (a) 200 rpm, (b) 400 rpm, (c) 600 rpm, and (d) 800 rpm. 59 Figure 1-43. Preparation procedure of the helical nanowires using confined nanoporous silica as template. 60 Figure 1-44. (a) Released nanoporous silica nanofibers from the confining alumina matrix using selective chemical etching by 5 wt % phosphoric acid; scale bar: 100 nm. (b) Schematic nanopore morphologies of the confined silica formed inside alumina channels with 55-73nm diameters: stacked donuts (left), D-helix (middle), and S-helix. 60 Figure 1-45. SEM micrographs of released Ag nanowire arrays. (a) Large-area image. Scale bar: 1000m. (b) High-magnification side-view micrograph showing the ordered nanowires. Scale bar: 100 nm. 61 Figure 1-46. TEM micrographs of released nanowires composed of (a,b) Ag, (c) Ni, and (d) Cu2O. Insets in (b-d) are the SAED patterns. Scale bars: 100 nm. 61 Figure 3-1. Polymerization of PS-PLLA. 76 Figure 3-2. Polymerization of PS-PLA. 76 Figure 4-1. TEM micrographs of (a) PS130-PLLA106 (fPLLAv=0.49) and (b) PS36-PLLA32 (fPLLAv=0.49) thin films quenched from 180oC. In all following figures, the insets show the corresponding Fast Fourier transforms. 119 Figure 4-2. (a) TEM micrograph of oriented PS130-PLLA106 (fPLLAv=0.49) nanostructure formed on BA; (b) ED pattern obtained from the central area of the micrograph and shown in correct relative orientation. 119 Figure 4-3. (a) TEM micrograph of oriented PS130-PLLA106 (fPLLAv=0.49) nanostructure formed on HMB; (b) ED pattern from the central area of the micrograph and shown in correct orientation. 120 Figure 4-4. TEM micrograph of PS130-PLLA106 (fPLLAv=0.49) thin film after directional eutectic solidification with BA. 120 Figure 4-5. TEM micrographs of PS36-PLLA32 (fPLLAv=0.49) thin films (a) solidified from eutectic BA-polymer solution; (b) PLLA directionally crystallized on BA substrate at 80oC for 30 min. 121 Figure 4-6. TEM micrographs of PS36-PLLA32 (fPLLAv=0.49) thin films (a) solidified from eutectic HMB-polymer solution and (b) PLLA directionally crystallized on HMB substrate at 80oC for 3 min; (c) 30 min. 121 Figure 4-7. Suggested phase diagrams of crystallizable solvent-polymer systems for (a) strongly segregated high Mn and (b) weakly segregated low Mn PS-PLLA. 122 Figure 4-8. Illustration of morphological evolution for the oriented nanostructures in PS-PLLA. 122 Figure 4-9. (a) Illustration and (b) FESEM micrograph of oriented PS130-PLLA106 (fPLLAv=0.49) lamellar thin films induced by a crystallizable solvent after hydrolysis of PLLA. 123 Figure 4-10. The TEM micrographs of solution-cast (a) PS85-PLLA41 (fPLLAv=0.35); (b) PS197-PLLA72 (fPLLAv=0.3); (c) PS280-PLLA97 (fPLLAv=0.29) and (d) PS364-PLLA109 (fPLLAv=0.26). The corresponding azimuthally scanned one-dimensional SAXS profiles are also obtained as shown. 124 Figure 4-11. (a) The tapping-mode SPM phase micrograph and (b) TEM micrograph stained by RuO4 for spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slide from chlorobenzene. 125 Figure 4-12. The tapping-mode SPM phase micrographs of the surfaces of spin coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slide by using different selective solvents for spin coating: (a) THF (vapor pressure at 20oC: 131.5 mmHg); (b) benzene (vapor pressure at 20oC: 70 mmHg); (c) chlorobenzene (vapor pressure at 20oC: 12 mmHg); (d) very slow evaporation rate. The insets show the Fourier-transform patterns of the SPM micrographs. 125 Figure 4-13. The tapping-mode SPM phase micrographs of the surfaces of spin coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slide by using different neutral solvents for spin coating: (a) chloroform (vapor pressure at 20oC: 159.6 mmHg); (b) 1,2-dichloroethane (vapor pressure at 20oC: 61 mmHg); (c) 1,1,2-trichloroethane (vapor pressure at 20oC: 17.1 mmHg) 126 Figure 4-14. The TEM micrographs of the spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slide by using different neutral solvents for spin coating: (a) chloroform (vapor pressure at 20oC: 159.6 mmHg); (b) 1,2-dichloroethane (vapor pressure at 20oC: 61 mmHg); (c) 1,1,2-trichloroethane (vapor pressure at 20oC: 17.1 mmHg) 126 Figure 4-15. The tapping-mode SPM phase micrographs of spin-coated thin films on glass slide from chlorobenzene: (a) PS364-PLLA109 (fPLLAv=0.26); (b) PS280-PLLA97 (fPLLAv=0.29); (c) PS197-PLLA72 (fPLLAv=0.3) and (d) PS85-PLLA41 (fPLLAv=0.35). The inset shows the enlarged area of the micrograph. 127 Figure 4-16. The tapping-mode SPM phase micrographs of solution-cast film on glass slide from selective solvent (chlorobenzene) at (a) PS364-PLLA109 (fPLLAv=0.26) and (b) PS355-PLA112 (fPLAv=0.27). 128 Figure 4-17. The tapping-mode SPM phase micrographs of solution-cast film on glass slide from neutral solvent (1,1,2-trichloroethane) at (a) PS364-PLLA109 (fPLLAv=0.26) and (b) PS355-PLA112 (fPLAv=0.27). 128 Figure 4-18. The tapping-mode SPM phase micrographs of spin-coated PS355-PLA112 (fPLAv=0.27) thin films on glass slide from chlorobenzene. 129 Figure 4-19. (a) Before hydrolysis; (b) after hydrolysis of the tapping-mode SPM height micrographs of the morphology at the bottom of nanopatterns for spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slide from chlorobenzene at ambient temperature. 129 Figure 4-20. The tapping-mode SPM (a) height and (b) phase micrograph of the morphology at the bottom of nanopatterns for spin-coated PS364-PLLA109 (fPLLAv=0.26) thin film on glass slide at 50oC. 130 Figure. 4-21. The tapping-mode SPM phase micrographs of spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on various surfaces from chlorobenzene: (a) glass slide; (b) carbon-coated glass slide; (c) indium tin oxide (ITO) glass; (d) silicon wafer. 130 Figure 4-22. The Schematic illustrations of cross section view for PS-PLLA thin films by spin coating at (a) room temperature and (b) 50oC. 131 Figure 4-23. The Schematic illustration of formation of PS-PLLA nanopattern prepared by spin coating, similar to the mechanism proposed by Kim and co-workers, where fs is the volume fraction of solvent and d is the depth of thin film. 131 Figure 4-24. The (a) top view and (b) cross-section view FESEM micrographs of spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on silicon wafer from chlorobenzene at 50oC after hydrolysis. 132 Figure 4-25. (a) 3D tapping-mode SPM height micrograph of SPM for spin-coated PS364-PLLA109 (fPLLAv=0.26) thin films on glass slides after hydrolysis. (b) Schematic illustration of PS-PLLA nanopattern prepared by spin coating. 132 Figure 4-26. Schematic illustration of the experimental procedure for the preparation of helical nanocomposites and inorganic nanohelices via chiral block copolymer (PS267-PLLA118 (fPLLAv=0.33)) templates.. 133 Figure 4-27. Transmission electron microscopy (TEM) mass-thickness-contrast micrographs of 50nm-thickness microsections for (a) RuO4 staining PS-PLLA helical nanostructure (PS267-PLLA118 (fPLLAv=0.33)); (b) PS/SiO2 helical nanocomposite without staining. 133 Figure 4-28. TEM mass-thickness-contrast micrographs of (a) 70nm-thickness; (b) 150nm-thickness microsections for PS/SiO2 helical nanocomposites. Schematic illustrations of the helical nanocomposites with (c) 70nm-thickness; (d) 150nm-thickness along the central axes of the nanohelices. Insets represent the corresponding top-view TEM projection micrographs from the helical nanocomposites. 134 Figure 4-29. (a) Field emission scanning electron microscopy (FE-SEM) micrograph; (b) schematic illustration and (c) EDX of SiO2 nanohelices from PS/SiO2 helical nanocomposites after 24hr UV treatment (λ = 254 nm). 135 Figure 4-30. FE-SEM micrograph and (b) schematic illustration of SiO2 helices after partially removing PS template by UV degradation. 135 Figure 4-31. FE-SEM micrograph of SiO2 helices after drying by supercritical fluid and then removing PS template by UV degradation. 136 Figure 4-32. FE-SEM micrograph of SiO2 nanohelices after sintering at 500oC (heating rate = 1 oC/min). 136