Nanoscale patterning of organic molecules has received considerable attention in current nanoscience for a broad range of technological applications. In order to provide a viable approach, this thesis describes catalytic stamp lithography, a novel soft-lithographic process that can easily produce sub-100 nm patterns of organic monolayers on surfaces. Catalytic stamps were fabricated through a two-step procedure in which the nanoscale patterns of transition metal catalysts are first produced on SiOx/Si surfaces via the use of self-assembled block-copolymers, followed by the production of the poly(dimethylsiloxane) (PDMS) stamps on top of the as-patterned metals. Simply peeling off the as-formed PDMS stamps removes the metallic nanostructures, leading to the functional stamps. A number of different patterns with various metals were produced from a commercially available family of block copolymers, polystyrene-block-poly-2-vinylpyridine, by controlling the morphology of thin-film templates through the modulation of molecular weights of polymer blocks or solvent vapor annealing. Using these catalytic stamps, hydrosilylation-based catalytic stamp lithography was first demonstrated. When terminal alkenes, alkynes, or aldehydes were utilized as molecular inks, the metallic (Pt or Pd) nanopatterns on catalytic stamps were translated into corresponding molecular arrays on H-terminated Si(111) or Si(100) surfaces. Since localized catalytic hydrosilylations took place exclusively underneath the patterned metallic nanostructures, the pattern formations were not affected by ink diffusion and stamp deformation even at the sub-20 nm scale, while maintaining the advantages of the stamp-based patterning (i.e., large-area, high-throughput capabilities, and low-cost). The concept of catalytic stamp lithography was further extended with other catalytic reactions, and successful nanoscale patterning was performed using hydrogenation (on azide-terminated SiOx surfaces) and the Heck reaction (on alkene- or bromphenyl-terminated SiOx surfaces). A range of nanopatterned surfaces with different chemical functionalities, including thiol, amine, and acid, were created, and they were further modified through appropriate chemical reactions. The potential utility of this simple approach for the construction of a higher degree of nanoarchitectures was suggested.

Supramolecular copolymers have become of increasing interest in recent years for the search of new materials with tunable properties. In particular, metallo-supramolecular block copolymers have seen important progresses since the last five years. In this thesis, a library of metallo-supramolecular amphiphilic block copolymers containing a hydrophilic block, linked to a hydrophobic block, through a metal-ligand complex has been investigated. The micelles formed in water from these copolymers were characterized by AFM and TEM and exhibited a different behavior compared to their covalent counterpart. Furthermore, a novel strategy to control the formation of amphiphilic brushes from metallo-supramolecular block copolymers has been developed. Starting from a heteroleptic block copolymer, the initial low molecular weight counterions were exchanged for polymeric ones, leading to the formation of complex architectures. Another part of this thesis is dedicated to the use of metal-ligand interactions located at the extremity of micelles. Since ligands are located at the extremity of the coronal chains, they are available for complexation with metal ions. The effect of the addition of various metal ions to this system was studied in the dilute regime by dynamic light scattering, and different situations have been observed depending on the metal-to-ligand ratio and to the nature of the metal ions. In more concentrated solutions, a second hierarchical level is reached leading to the formation of a micellar gel, due to the formation of intermicellar bridges. Rheological measurements revealed that the characteristic behavior of those gels critically depends on the added metal ions. Finally, the self-assembly of a metallo-supramolecular block copolymer in thin films was investigated. Due to the presence of the charged complex at the junction of the two blocks, this copolymer could be considered as a triblock with a highly immiscible block that effects the orientation of the cylindrical microdomains and the lateral ordering.

The phase behaviors and microstructures of various realistic and model mixtures of macro and micro molecules, such as polyolefin solutions and nanoparticle block copolymer composites, have been accurately predicted by the application of Statistical Associating Fluid Theory (SAFT) based approaches through various extensions that improve both the physical description of molecular interactions and efficiency of computations. The extensions are presented in a generic sense that is applicable to other studies. These rigorously derived theories have been demonstrated to capture material structure-property relationships and can be applied broadly to other fields including biology, medicine and energy industry. On the phenomenogical scale, the novel SAFT-Dimer equation of state has been extended to study the liquid-liquid phase boundary (cloud point) in polyolefin solutions. A simplified model of the polyolefin molecules has been followed and the effect of various parameters, such as temperature, molecular weight, solvent quality and comonomer content, on the phase behavior has been successfully captured by the theoretical model through comparison with experimental measurements. The presented approach requires less parameters than previous methods and is of critical value to the industrial productions of polymers, especially polyolefins with long branches. On the molecular scale, the interfacial SAFT (iSAFT) Density Functional Theory (DFT) has been extended to include a dispersion free energy functional that explicitly accounts for molecular correlations. The Order-Disorder Transition (ODT) between lamellar and disordered phase has then been investigated for pure block copolymer and copolymer nanocomposite systems. The extension has been shown to dramatically improve the ODT predictions of iSAFT as well as the self assembled microstructures in nanocomposites over previous DFT calculations, in comparison to coarse grained molecular simulations. The behavior of the equilibrium spacing of ordered structures is also examined against the variation of copolymer size and interactions. An efficient numerical scheme, Fast Fourier Transform (FFT), has been implemented and shown to drastically increase the computation efficiency. The theory has then been extended to study block copolymer morphologies with density variations in multiple dimensions. Comprehensive phase diagrams including lamellar, cylindrical and disordered phases have been obtained for copolymer nanocomposites for the first time using a single framework molecular theory. In addition, the nanoparticle induced morphological transition between cylindrical and lamellar phase has been studied using a pseudo arc-length continuation method. Transition evolution is tracked and metastable morphologies are examined and compared with existing experimental reports and theoretical calculations. With these extensions, iSAFT offers a powerful prediction tool that closely relates molecular structure to thermophysical properties and provides an efficient alternative to screen parameter space for specified material properties.

A series of immiscible crystalline-crystalline diblock copolymers, poly(ethylene oxide)-b-(£`-caprolactone) (PEO-b-PCL), were blended with (3-phenyl-3,4-dihydro-2H-1,3-benzoxazin-6-yl) methanol (Pa-OH). FT-IR analyses provide that the ether group of PEO is a stronger hydrogen bond acceptor than the carbonyl group of PCL with the hydroxyl group of Pa-OH. Pa-OH after curing results in the excluded and confined PCL phase based on differential scanning calorimeter (DSC) analyses. In addition, the mesoporous structure was proved with the increasing the ratio of PCL to PEO in block copolymers by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) analyses and N2 adsorption-desorption isotherms (BET) The poly(styrene-b-4-vinyl pyridine) diblock copolymer was blended with Pa-OH monomer. FT-IR analyses demonstrate the intermolecular hydrogen bonding interaction between the pyridine group of P4VP and the hydroxyl group of Pa-OH. After curing, the block copolymers were incorporated into polybenzoxazine resin to access the nanostructure through the reaction induced microphase separation mechanism by TEM and SAXS analyses.

The fabrication of one-dimensional (1-D) polymeric photonic crystals from the self-assembly of ultra-high-Mw polystyrene-b-polyisoprene (PS-PI) block copolymers (BCPs) were conducted in this study. Well-ordered microphase-separated lamellar structures can be observed in the ultra-high-Mw PS-PI BCPs in the bulk by transmission electron microscopy (TEM) and ultra-small angle X-ray scattering (USAXS). To fabricate large-area and well-oriented lamellar microstructures with parallel orientation to the substrate, substrate-induced microstructural orientation with the accompanying solvent annealing method (i.e., solvent-induced orientation) was carried out in the PS-PI film. By grazing-incidence ultra-small angle X-ray scattering (GIUSAXS), scanning probe microscope (SPM) and cross-sectional TEM morphological observation, identification of the microstructural orientation in the PS-PI film can be achieved. A disordered wormlike morphology is observed in the as-spun PS-PI thin film from toluene on the PS-grafting substrate and on neat glass or wafer. This is attributed to the fast solidification of the disordered microstructure due to fast evaporation rate of the toluene solvent. After solvent annealing by the PS-selective or PI-selective solvents such as divinylbenzene (DVB) (neutral but highly PS-selective), benzene (PS-selective) and cyclohexane (PI-selective), parallel lamellar microstructures can be obtained in the PS-PI films on the PS-grafting substrate. By contrast, the coexistence of parallel and perpendicular lamellar microstructures is obtained in the PS-PI film from toluene after solvent annealing by neutral toluene on the PS-grafting substrate or by PS-selective benzene on the neat glass or wafer. This indicates that the formation of the parallel lamellar microstructures is mainly determined by both solvent-induced and substrate-induced orientation. In contrast to the as-spun disordered morphology from toluene, well-ordered parallel lamellar microstructures with few defects was found in the as-spun PS-PI film from DVB on the PS-grafting substrate, whereas parallel lamellar microstructures with many defects was observed in the as-spun PS-PI film from DVB on the neat glass or wafer. This further demonstrates that the PS-grafting substrate indeed plays an important role on the fabrication of well-ordered parallel lamellar microstructures. Interestingly, once the initial morphology of the PS-PI BCP reaches a relative stable state (i.e., parallel lamellar microstructures versus disordered wormlike morphology), it is hardly to trigger the microstructural reorientation by the subsequent solvent annealing. We suggest that the stable initial morphology in the PS-PI film may create high energy barrier for microstructural reorientation. With the controllable microstructural orientation, a PS-PI thick film having large-area and well-oriented parallel lamellar microstructures can be successfully carried out. Therefore, 1-D polymeric photonic crystals from the self-assembly of the lamella-forming PS-PI BCPs can be achieved. The in-situ UV reflectance spectra show that the reflective band shifts from ultraviolet wavelength to visible wavelength was observed in the lamella-forming PS-PI thick film with elapse of time by solvent annealing. Notably, the band gap can be recovered to the initial state once the solvent is removed, indicating the reversible process. As the results, the solvatochromic BCP photonic crystals can be successfully carried out by the manipulation of the solvent swelling in the large-area and well-oriented lamella-forming PS-PI BCP film.

Double crystalline block copolymers (BCPs), syndiotactic poly(4-methyl-1-pentene)-b-poly(L-lactide) (sPMP-PLLA) and syndiotactic poly(4-methylstyrene)-b-poly(L-lactide) (sPMS-PLLA), were synthesized to examine crystallization effect on the self-assembled morphologies in the double crystalline BCPs. Because of the stainable chemical structures, morphological observation can be carried out in these double crystalline BCPs. Also, different microphase-separated structures including lamellae and hexagonally packed cylinders were explored to study the shape effect for double crystallization. Based on differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) results, both sPMP and PLLA blocks are able to crystallize in the sPMP-PLLA BCP (fsPMPv=0.52) at the crystallization temperature (Tc) from 80¢XC to 120¢XC. Notably, temperature-dependent phase transitions between the PLLA polymorphisms are obtained by WAXD. By using small-angle X-ray scattering (SAXS) and transmission electron microscope (TEM), the microphase-separated lamellar structures can be observed in the sPMP-PLLA BCP (fsPMPv=0.52). Also, the preservation of the lamellar morphology at all Tcs (80¢XC~120¢XC) indicates that the sPMP and PLLA crystallization can be strongly confined within the lamellar microstructures due to the strong segregation strength of the sPMP-PLLA (fsPMPv=0.52) BCP. This can be further demonstrated by the ambiguous birefringence under polarized light microscope (PLM). According to the time-resolved SAXS and WAXD profiles at 90oC and 110oC, the sPMP block crystallizes first and induces the enlargement of the BCP long period. Also, the leading sPMP crystallization gives rise to the robust lamellar microstructural template and result in strong confinement for the subsequent PLLA crystallization. In the sPMS-PLLA BCP (fsPMSv=0.58), the microphase-separated lamellar nanostructures can be found by SAXS and TEM. DSC analysis shows that PLLA block is able to crystallize as Tc=90¢XC~100¢XC; the sPMS block is able to crystallize as Tc ≥120oC. By self-nucleation processes, both sPMS and PLLA blocks are able to crystallize. Therefore, by the manipulation of the respective crystallization, two-stage crystallization and coincident crystallization, systematic studies in the semi-crystallization, double crystallization and coincident double crystallization with the accompanying environmental Tg effect and BCP segregation strength can be carried out in the lamella-forming sPMS-PLLA (fsPMSv=0.58) BCP. By SAXS and TEM, the microphase-separated lamellar microstructures can be preserved in the self-assembly of the sPMS-PLLA (fsPMSv=0.58) BCP whatever the PLLA crystallization occurs under hard confinement (Tc,PLLA<Tg,sPMS) or soft confinement(Tc,PLLA˃Tg,sPMS). For the sPMS crystallization under soft confinement, the lamellar microstructures can be preserved as Tc,sPMS ≤140oC, whereas the breakout morphology by the sPMS crystallization is found as Tc,sPMS ≥150oC. As a result, the final morphologies is strongly dependent on the BCP segregation strength in the lamella-forming sPMS-PLLA (fsPMSv=0.58) BCP. In sPMS-PLLA BCP (fsPMSv=0.7), hexagonally-packed PLLA cylinders in the sPMS matrix are obtained by SAXS and TEM. DSC analysis shows that the sPMS block is able to crystallize as Tc=130¢XC~180¢XC, whereas no PLLA crystallization can be found in the cylinder-forming sPMS-PLLA BCP (fsPMSv=0.7). This indicates that the 2-D cylindrical shape might give rise to the strong confined effect and result in non-crystallizable PLLA. According SAXS and TEM results, the intrinsic hexagonally-packed cylinders can be preserved after the sPMS crystallization at 130oC due to the strong BCP segregation strength. By contrast, the crystallization driving force may overwhelm the microphase separation so as to form breakout morphology in the sPMS-PLLA (fsPMSv=0.7) BCP as Tc≥150¢XC.

No description available.

No description available.

My Ph.D. thesis is presented in two parts. In the first part, I describe the preparation of organic-inorganic hybrid micelles formed from poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) block copolymers and CdSe quantum dots (QDs). Several distinct morphologies were observed including, spheres, finite-sized wormlike networks and clusters of hollow vesicles. A series of experiments were carried out to explore whether these hybrid colloids were thermodynamically stable or formed under kinetic control. Upon addition of 2-propanol (2-PrOH) to a chloroform solution containing a mixture of PS404-b-P4VP76 plus CdSe QDs (2-PrOH is a good solvent for P4VP block and a precipitant for PS block and QDs), uniform spherical micelles formed almost instantly, with a PS core and a thin P4VP corona to which the QDs were attached. Vigorous stirring of this solution for two days led to the formation of three-dimensional wormlike networks consisted of Y-junctions and cylindrical struts, terminated by bulbous spherical end-caps. Even more profound structural changes occurred when the solution was subjected to prolonged magnetic stirring (e.g. 1 month). ii In contrast, manipulating the chemical composition of the initial block copolymer could trigger a spontaneous structural transition from sphere to network of wormlike micelles over 2 h without the need of stirring. The second part of the thesis begins by describing a modular approach for preparing polyferrocenyldimethylsilane (PFS) block copolymers via a Cu-catalyzed alkyne/azide coupling reaction to covalently combine two homopolymers synthesized separately. This strategy opens the door to a broad library of novel functional PFS block copolymers, for example, poly(ferrocenyldimethylsilane-b-N-isopropyl acrylamide) (PFS-b-PNIPAM). In an attempt to expand our understanding of PFS block copolymer self-assembly in polar solvents, I investigated the self-assembly of a new polymer (PFS26-b-PNIPAM105) in alcohol solvents. When the block polymer was dissolved in methanol, ethanol and 2-propanol, it formed long fiber-like micelles with uniform width. I also showed that micelles of this polymer underwent seeded growth in methanol, leading to cylindrical micelles that were nearly mono- dispersed in length.

My Ph.D. thesis is presented in two parts. In the first part, I describe the preparation of organic-inorganic hybrid micelles formed from poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) block copolymers and CdSe quantum dots (QDs). Several distinct morphologies were observed including, spheres, finite-sized wormlike networks and clusters of hollow vesicles. A series of experiments were carried out to explore whether these hybrid colloids were thermodynamically stable or formed under kinetic control. Upon addition of 2-propanol (2-PrOH) to a chloroform solution containing a mixture of PS404-b-P4VP76 plus CdSe QDs (2-PrOH is a good solvent for P4VP block and a precipitant for PS block and QDs), uniform spherical micelles formed almost instantly, with a PS core and a thin P4VP corona to which the QDs were attached. Vigorous stirring of this solution for two days led to the formation of three-dimensional wormlike networks consisted of Y-junctions and cylindrical struts, terminated by bulbous spherical end-caps. Even more profound structural changes occurred when the solution was subjected to prolonged magnetic stirring (e.g. 1 month). ii In contrast, manipulating the chemical composition of the initial block copolymer could trigger a spontaneous structural transition from sphere to network of wormlike micelles over 2 h without the need of stirring. The second part of the thesis begins by describing a modular approach for preparing polyferrocenyldimethylsilane (PFS) block copolymers via a Cu-catalyzed alkyne/azide coupling reaction to covalently combine two homopolymers synthesized separately. This strategy opens the door to a broad library of novel functional PFS block copolymers, for example, poly(ferrocenyldimethylsilane-b-N-isopropyl acrylamide) (PFS-b-PNIPAM). In an attempt to expand our understanding of PFS block copolymer self-assembly in polar solvents, I investigated the self-assembly of a new polymer (PFS26-b-PNIPAM105) in alcohol solvents. When the block polymer was dissolved in methanol, ethanol and 2-propanol, it formed long fiber-like micelles with uniform width. I also showed that micelles of this polymer underwent seeded growth in methanol, leading to cylindrical micelles that were nearly mono- dispersed in length.