Novel, highly functional rod-like copolymers have been synthesized by alternating copolymerization of N, N, Nâ , Nâ -tetraalkyl-4, 4â -diaminostilbenes (TDAS) with maleic anhydride. Dynamic light scattering, 2H solid state NMR and persistence length measurement reveal high chain rigidity of the polymer backbone. Double quantum heteronuclear local field solid state NMR spectroscopy (2Q-HLF Solid State NMR) has been employed to investigate the chain structure of ¹³C labelled copolymer. The torsional angle of the H-13C-13C-H part of the anhydride ring was zero degrees, indicating an all cis configuration of the H-13C-13C-H moiety of the anhydride ring. Rod-coil block copolymers containing rigid polyampholyte blocks were designed and synthesized by addition-fragmentation chain transfer (RAFT) copolymerization. The rigid polyampholytes blocks were formed by hydrolysis of alternating copolymers and the flexible coil block consists of poly(oligo(ethylene glycol) methacrylate). The rod-coil block copolymers form polyion complex (PIC) aggregates even when the polyampholyte blocks are charge imbalanced. The aggregates did not dissociate upon the addition of high concentrations of NaCl unlike the dissociation of flexible polyampholytes in NaCl solution. These unique solution properties are induced by 'like-charge attractions' of the rigid polyampholytic alternating copolymer chains. An example, of what is birefringent to be a novel class of material, has been prepared which enables the control of the birefringence of a polymer film by controlling the rotation of aromatic groups pendant to the polymer backbone. A linear rigid bisphenol monomer, 4,4′-dihydroxyterphenyl (DHTP), has been incorporated into poly(aryl ether sulfone)s (PAES) in a study to impart crystallization to these amorphous polymers. Three bisphenols, 4, 4′-isopropylidenediphenol, 4, 4′-(hexafluoroisopropylidene)diphenol and 4,4′-dihydroxybiphenyl have been copolymerized with DHTP and dichlorodiphenylsulfone. Only the segmented polysulfone containing 50% BP and 50% DHTP was semi-crystalline. This PAES had a melting temperature (Tm) 320°C in the first heating cycle of a DSC measurement and the presence of crystallites was confirmed by wide angle X-ray diffraction (WAXS). / Ph. D.

Two novel classes of siloxane containing, organic-inorganic block copolymers were prepared using different synthetic approaches. The first copolymers were alternating poly(arylene ether phosphine oxide)-poly(dimethylsiloxane) systems, prepared via oligomeric silylamine-hydroxyl reactions. Secondly, segmented nylon 6,6-poly(dimethylsiloxane) block copolymers were synthesized via a non-aqueous adaptation of the "nylon 6,6 salt" hydrolytic polyamidization, using bis(aminopropyl) dimethylsiloxane oligomer as a co-reactant. Three series of "perfectly" alternating block copolymers were produced from well characterized hydroxyl-terminated poly(arylene ether phosphine oxide) and dimethylamine-terminated poly(dimethylsiloxane) oligomers, in order to investigate both block length and chemical composition effects. Copolymerization in chlorobenzene resulted in high molecular weight materials capable of forming optically clear, nanophase separated films, which displayed unusual morphologies and good mechanical strength. Thermal gravimetric analysis showed high thermo-oxidative stability and increasing char yield with increasing siloxane content. Additional thermal and mechanical investigations provided evidence of selective phase mixing, particularly at shorter block lengths. Surface analysis showed an enrichment of the siloxane blocks at the air-polymer interface in comparison to the bulk state. This behavior increased in proportion to the length of the parent siloxane oligomers. Evaluation of selected optical properties, e.g., refractive indices, revealed linear trends resulting in values of compositionally weighted averages. Conversely, a series of nylon 6,6-siloxane copolymers were produced from the polycondensation of preformed propylamine-terminated poly(dimethylsiloxane)s, solid nylon 6,6 salt and a corresponding amount of adipic acid to afford siloxane-amide semi-crystalline copolymers with siloxane content ranging from 10 to ~45 wt%. The characterization of high molecular weight and covalent siloxane-amide linkages was hindered by insolubility. For example, crystallinity of the nylon 6,6 precluded the use of common solution techniques, while the susceptibility of the siloxane blocks towards ionic redistribution prevented the use of strongly acidic solvents. However, development of a novel analytical technique using solid state 13C NMR and liquid-solid extraction provided evidence for the presence of covalent bonding between the dissimilar oligomer chains. Thermal gravimetric analysis of resultant copolymers revealed an increase in char yield with increasing siloxane content, a preliminary indicator of increased fire resistance, which was supported by subsequent qualitative Bunsen burner observations. Differential scanning calorimetry showed retention of the polyamide crystalline melt with levels of siloxane incorporation of up to 45 weight %. In conclusion, two novel classes of polydimethylsiloxane containing block copolymers have been successfully synthesized, despite the complications created as a result of the polar/non-polar interactions developed between a semi-inorganic polydimethylsiloxane and the hydrocarbon based polyarylene ethers and nylon 6,6. / Ph. D.

As the world population grows, a persistent pressure on natural resources remains. Resource requirements have extensively expanded due to industrialization. Several technological advancements continually aim to alleviate these resource shortages by targeting existing shortcomings in effective and efficient material design. Practical, high-performing, and economical materials are needed in several key application areas, including energy storage, energy harvesting, electronics, catalysis, and water purification. Further development into high-performing and economical materials remain imperative. Innovators must seek to develop technologies that overcome fundamental limitations by designing materials and devices which address resource challenges. Carbon serves as a versatile material for a wide range of applications including purification, separation, and energy storage owing to excellent electrical, physical, and mechanical properties. One-dimensional (1D) carbon fiber in particular is renowned for excellent strength with high surface-to-volume ratio and is widely commercially available. Although an exceptional candidate to address current energy and environmental needs, carbon fibers require further investigation to be used to their full potential. Emerging strategies for carbon fiber design rely on developing facile synthetic routes for controlled carbon structures. The scientific community has shown extensive interest in porous carbon fabrication owing to the excellent performance enhancement in separation, filtration, energy storage, energy conversion, and several other applications. This dissertation both reviews and contributes to the recent works of porous carbon and their applications in energy and environmental sciences. The background section shows recent development in porous carbon and the processing methods under investigation and current synthetic methods for designing porous carbon fibers (PCF). Later sections focus on original research. A controlled radical polymerization method, reversible addition-fragmentation chain transfer (RAFT), enabled a synthetic design for a block copolymer precursor, poly(methyl methacrylate) (PMMA) and polyacrylonitrile (PAN). The block copolymer (PMMA-b-PAN) possesses a unique microphase separation when electrospun and develop narrowly disperse mesopores upon carbonization. The PMMA and PAN domains self-assemble in a kinetically trapped disordered network whereby PMMA decomposes and PAN cross-links into PCF. The initial investigation highlights the block copolymer molecular weight and compositional design control for tuning the physical and electrochemical properties of PCF. Based on this study, mesopore (2 – 50 nm) size can be tuned between 10 – 25 nm while maintaining large surface areas, and the PAN-derived micropores (< 2 nm). The mesopores and micropores both contribute to the development of the unique hierarchical porous carbon structure which brings unprecedented architectural control. The pore control greatly contributes to the carbon field as the nano-scale architecture significantly influences performance and functionality. The next section uses PCF to clean water sources that are often tainted with undesirable ions such as salts and pollutants. Deionization or electrosorption is an electrochemical method for water purification via ion removal. I employed the PCFs as an electrode for deionization because of their high surface area and tunable pore size. Important for deionization, the adsorption isotherms and kinetics highlight the capacity and speed for purification of water. I studied PCF capacitive filtration on charged organic salts. Because PCF have both micropores and mesopores, they were able to adsorb ions at masses exceeding their own weight. The PFC adsorption efficiency was attributed to the diffusion kinetics within the hierarchical porous system and the double layer capacitance development on the PCF surface. In addition, based on the mechanism of adsorption, the PCFs showed high stability and reusability for future adsorption/desorption applications. The PCF performance as an electrosorption material highlights the rational design for efficient electrodes by hierarchical interconnected porosity. Another application of PFCs is updating evaporative desalination methods for water purification. Currently distillation is not widely used as a source of potable water owing to the high cost and energy requirement. Solar desalination could serve as a low-cost method for desalination; however, the evaporation enthalpy of water severely limits practical implementation. Here I apply the pore design of PCF as a method for water nano-confinement. Confinement effects reduce water density and lowers evaporation enthalpy. Desalination in PCF were studied in pores < 2 nm to 22 nm. The PCF pore size of ~ 10 nm was found to be the peak efficiency and resulted in a ~ 46% reduction in enthalpy. Interestingly, the PCF nano-confinement also contributed to the understanding in competing desorption energy for evaporation in micropores. The pore design in PCF also shows confinement effects that can be implemented in other environmental applications. Lastly, the block copolymer microphase morphology was explored in a vapor induced phase separation system. The resulting PCF properties showed a direct influence from the phase separation caused by nonsolvent. At low nonsolvent vapor, a disordered microphase separation occurred, however upon application of nonsolvent vapor, the polymer chains reorganized. The reorganization initially improved mechanical properties by developing more long-range ordered graphic chains in the PAN-derived carbon. However, at higher nonsolvent vapor concentrations, the fibers experienced polymer precipitation which resulted in bead and clump formation in the fiber mats. The beads and clumps lowered both mechanical properties and electrochemical performance. The vapor induced phase separation showed a method for enhancing mechanical properties without compromising electrochemical performance in flexible carbon fibers. / Doctor of Philosophy / Nanomaterials possess mechanical, physical, and electrical properties to address important growing demands for precious resources such as clean water and energy. Many advancements in nanomaterials focus on improving fine-tune architectures which facilitate efficiency in composites, filtration systems, catalytic systems, energy storage devices, and electronics. Carbon material has remained a valuable candidate in these fields owing to its abundancy economical cost, and excellent properties. Several carbon forms provide unique characteristics including 0D dots, 1D fibers, 2D sheets, and 3D monoliths. Of these, 1D fibers possess excellent strength, resiliency, and conductivity and have been commercially employed in modern automotive, airplanes, membranes, and conductors. However, traditional carbon fiber fabrication does not match the growing needs in performance. Therefore, in this dissertation I explore the design and processing of carbon fibers for controlled architectures. These designs were then systematically studied in filtration systems, solar desalination, and flexible electronics. Block copolymers provide a new way to combine polymers for drastically new materials and effects. Firstly, I conducted a comprehensive study on the synthesis and composition of this block copolymer which laid the foundation for future carbon fiber design. The polymer consists of two chains – one chain to develop carbon structures upon heating; the second which decomposes into pores upon heating. Therefore, with these two chains, a highly porous carbon fiber can be created. The reaction I studied could mostly be controlled with time to change the length of each chain. Ultimately, the pore size and surface area depend on the relative lengths of each chain. Future studies, including ones in this work, could therefore tune pore size and surface area for many applications. Carbon fibers with graphitic structure are inherently conductive and thereby attract charged molecules in a solution. Diffusion and capacity serve as major factors in these types of systems. With the aforementioned control of the carbon fibers a diffusion study was conducted with charged pollution ions. Owing to the conductive nature, a voltage supply was attached to the fibers, which would adsorb ions electrostatically, termed "electrosorption". The electrosorption performance within the carbon fibers elucidated the interconnected porous structure and how ions orientate themselves along the surface of the fibers. In addition, with the development of ion orientation along the surface of the fibers, a greater than 1:1 ratio of carbon weight to ion weight adsorbed developed owing to the diffusion and ion stacking capabilities. Additionally, the study provides deeper investigation into movement of ions within confined nano-porous material. The ever-growing need for renewable resources such as fresh water has pressured development into more efficient material. Solar desalination has attractive qualities which makes it a focus for micro-scale studies. One of the major limitations lies in the high energy input change liquid water into vapor. At 100 °C for boiling, desalination lacks sufficient efficiency for large-scale applications in evaporation. However, by utilizing nano-scale material, the fundamental properties of water can be altered. The carbon fibers were then created with various nano-pore sizes which revealed nano-confinement effects when subject to solar heating. With the shrinking of pore sizes, the density of water also decreased. A lower density means less energy was required to convert water from a liquid to a vapor state. The carbon fibers helped reveal real applications into confinement effects on water based on pore size. Apart from just desalination, this means future environmental application can utilize this knowledge for more effective and smart designs. The carbon fibers outstanding electrical and mechanical properties have spurred research and development since the mid-1900s. Since then, carbon fiber technologies have grown from facile and efficient productions means, to high end, high performance smart design. The work presented here furthers two major components: first, the high-performance design of porous carbon fiber; second, the fundamental principles in nano-material properties and their applications. By first constructing a design of polymer synthesis and then subsequent studies, development of nano-porous carbon energy progresses knowledge on smart and efficient designs. These materials provide a platform for future energy and environmental sciences.

Polysaccharides are known as among the most abundant natural polymers on the Earth. As this class of material is usually renewable, biodegradable, biocompatible in many contexts and environmentally friendly, it is of great interest to use these benign polymers to design and prepare materials, especially for applications with green and biomedical purposes. In this dissertation we will discuss novel pathways to two different types of polysaccharide-based materials: block copolymers and hydrogels. Block copolymers are composed of two or even more covalent bonded polymer blocks that have quite distinct properties. Synthesis of polysaccharide-based block copolymers is an attractive and challenging research topic, opening up promising application potential and requiring advances in polysaccharide regio- and chemoselectivity. Herein, we report two independent approaches to prepare these interesting and potential useful materials. In one approach, trimethyl cellulose was modified regiospecifically at the reducing end anomeric carbon to create an ω-unsaturated alkyl acetal by solvolysis with an ω-unsaturated alcohol. Then, olefin cross-metathesis, a known versatile and mild tool for polysaccharide chemical modification, was used to couple the trimethyl cellulose block with various polymer blocks containing acrylates. To demonstrate the method, trimethyl cellulose-b-poly(tetrahydrofuran), cellulose-b-poly(ethylene glycol), and cellulose-b-poly(lactic acid) were synthesized by this coupling strategy. In another approach, we introduced a simple and novel method to prepare dextran-based block copolymers. In this strategy, N-bromosuccinimide (NBS)/triphenyl phosphine (PPh3) was chosen to regioselectively brominate the only primary alcohol of linear unbranched dextran. The resulting dextran, bearing a terminal C-6 bromide, was coupled with several amine terminated polymers via SN2 substitution to obtain block copolymers, including dextran-b-polystyrene, dextran-b-poly(N-isopropylacrylamide) and dextran-b-poly(ethylene glycol). Dextran-b-poly(N-isopropylacrylamide) exhibits thermally-induced micellization as revealed by dynamic light scattering, forming micelles with 155 nm diameter at 40 °C. Dextran-b-polystyrene film was analyzed by small angle X-ray scattering, suggesting the existence of microphase separation. This dissertation also introduces a novel, simple and effective strategy to prepare polysaccharide-based hydrogels. Hydrogels are typically crosslinked hydrophilic polymers that have high water affinity and no longer dissolve in water. Polysaccharide-based hydrogels are of great interest to for biomedical applications due to their benefits including biocompatibility, polyfunctionality, and biodegradability. Recently the Edgar group has discovered that chemoselective oxidation of oligo(hydroxypropyl)-substituted polysaccharides impairs ketone groups at the termini of the oligo(hydroxypropyl) side chains. These ketones can condense with amines to form imines, leading hydrogel formation., Based on this concept, we prepared oxidized hydroxypropyl polysaccharide/chitosan hydrogels. This class of all-polysaccharide hydrogels exhibits a series of interesting properties such as tunable moduli (300 Pa to 13 kPa), self-healing, injectability, and high swelling ratios. To further explore imine-crosslinked hydrogels, we designed thermally responsive hydrogels by using a Jeffamine, a polyethylene oxide-b-polypropylene oxide-b-polyethylene oxide triblock copolymer with two terminal amines. As the Jeffamine has a lower critical solution temperature, oxidized hydroxypropyl cellulose/Jeffamine hydrogels display moduli that are tunable by controlling the temperature. / Doctor of Philosophy / Polysaccharide are natural polymers that are among the most abundant polymers on Earth. It is greatly in society's interest to extend the scope of their applications, due to the benign nature of polysaccharides. This dissertation mainly focuses on two polysaccharides: cellulose and dextran. Cellulose is a long linear polymer of linked glucose molecules. As cellulose is sustainable, biodegradable, non-toxic, affordable and accessable for chemical modification, it is a suitable polymer for biomedical and environmentally friendly application. Dextran is also a polymer chain made up only of glucose but connected with each other differently from cellulose by, bacterial fermentation, and it may be lightly branched. It is biocompatible in many situations and is biodegradable both in vivo and in the environment, thus it has been investigated for drug delivery and many other medical applications. Using these two polysaccharides, we designed and prepared two quite different classes of materials: block copolymers and hydrogels. Block copolymers consist of two or more different types of polymer blocks connected by strong covalent bonds. As block copolymerization enables construction of a single polymer comprising segments with distinct properties, it is appealing to synthesize a block copolymer which preserves the properties of natural polymers coupled to very different polymers, such as polyolefins (e.g. the polyethylene that is used for milk bottles). In order to prepare polysaccharide-based block copolymers, we developed two different synthetic routes to end-functionalize methyl cellulose and dextran , and these resulting products were used to prepare two independent series of polysaccharide-based block copolymers via combination (in other words, sticking the polysaccharide and, e.g., the polyethylene together end to end). This study confirms the feasibility of this method to make methyl cellulose-based and dextran-based block copolymers. We expect these classes of materials will have significant potential in applications including drug delivery, as compatibilizers for polymer blends of materials that otherwise cannot be mixed (polyolefin/polysaccharide), membrane and adhesive. Hydrogels are crosslinked polymer networks with high water affinity, and they have been heavily investigated in the field of tissue engineering, drug delivery, agriculture and 3D printing. Polysaccharide-based hydrogels are attractive materials for these applications because they are biocompatible, biodegradable and have polyfunctionality. However, any use of toxic small molecules to crosslink the hydrogels diminishes their usefulness in biomedical applications. In this work, we demonstrate a simple, green and efficient method for preparation of all-polysaccharide-based hydrogels. The starting materials, oxidized hydroxypropylpolysaccharide, were simply prepared by using household bleach (NaOCl) as the oxidation reagent. We discovered that oxidized hydroxypropyl polysaccharides readily form hydrogels with hydrophilic amine-containing polymers like chitosan (a natural polysaccharide that comes from shells of crustaceans like crabs or shrimp) and Jeffamines, affording interesting properties including tunable stiffness, self-healing, injectability, and responsiveness to acidity and temperature. We expect that this new class of hydrogel will be very promising for biomedical-related applications.

Block copolymers have been extensively applied in diverse fields including packaging, electrolytes, delivery devices, and biosensors. Multiple investigations have been carried out on polymeric materials for cargo delivery purpose to understand how they behave over time. Block copolymer micelles (BCMs) have demonstrated superiority to deliver cargo, especially in drug delivery due to their encapsulation of hydrophobic agents. This dissertation will mainly study BCMs for potential applications in cargo delivery. Methods to study BCMs, including NMR spectroscopy, relaxometry and diffusometry, can provide valuable molecular information, such as chemical structure, translational motion, inter- or intramolecular interaction, dynamics, and exchange kinetics. Therefore, this dissertation describes applications of versatile NMR methods to reveal the fundamental behaviors of block copolymer self-assemblies, such as their dynamic stability, cargo partitioning, polymer chain exchange, and chain distribution in solution. We have investigated two BCM systems. Poly(ethylene oxide)-b-(ε-caprolactone) (PEO-PCL) is a model system to study BCM dynamic stability. PEO-PCL can self-assemble into spherical micelles at 1% w/v in D2O-THF-d8 mixed solvents. We used NMR diffusometry to quantify diffusion coefficients and populations of micelles and unimers (i.e. free polymer chains in solution) over a range of temperature (21 – 50 °C) and solvent composition (10 – 100 vol % THF-d8). By mapping the micelle-unimer coexistence phase diagrams, we are able to enhance our ability to understand and design micelle structure and dynamics. Moreover, we can also probe the chain exchange kinetics between micelles using a new technique we developed – time-resolved NMR spin-lattice relaxation (T1) or TR-NMR. This technique is an analog to time-resolved small-angle neutron scattering (TR-SANS), which can monitor specific signal intensity changes caused after mixing of isotope-labeled micelle solutions. A second system, Pluronic® F127 (PEO99PPO69PEO99) is a test system to study BCM structure and dynamic changes upon drug uptake. Pluronic® F127 is a commercial copolymer that can solubilize different hydrophobic drugs in micelles. We successfully encapsulated three model drugs into Pluronic® F127 BCMs and investigated the effects of polymer concentration and drug composition on drug partitioning fractions. Also, we proposed to design and synthesize a series of block copolymers with varied glass transition temperatures in core-forming blocks. Using NMR diffusometry, we have measured the existing unimer concentrations in micellar solutions and correlated these results with chain mobility and internal chemical composition. Lastly, we have extended our expertise in NMR and polymers into the study of ion-containing polymer systems (polyelectrolytes). A critical problem in polymer science is the inability to reliably measure the molecular weight of polyelectrolytes. We are developing methods to solve this problem by using NMR diffusometry, rheology, scattering, and scaling theories to accomplish general molecular weight measurements for polyelectrolytes. In short, this dissertation describes studies to provide more perspectives on structural and dynamic properties at various time and length scales for polymeric materials. NMR measurements, in combination with many other advanced techniques, have given us a better picture of soft matter behaviors and provided guidance for synthesis and processing efforts, especially in block copolymer micelles for delivery purposes. / Doctor of Philosophy / Block copolymers have been extensively applied in diverse fields in packaging, electrolytes and nano-scale drug delivery carriers. In the area of cancer treatment, only a limited number of drug nanocarriers have been approved for clinical applications. Therefore, it is very important to understand the principles behind drug delivery for targeted purposes. There have been many studies on polymeric delivery carriers but their behaviors have not been completely understood. Therefore, we have tremendous interest in unraveling the mysteries in those polymeric systems. Among a multitude of techniques to study block copolymer materials, the NMR method serves as a potent tool for its non-destructive, chemical-specific and isotope-selective merits. NMR can provide basic information about block copolymer self-assembly and other polymeric properties, such as chemical structure, molecular interactions and diffusion coefficients of species of interests. Chapters 3, 4, 5, 6, and 7 have investigated different classes of polymeric materials, mainly block copolymer micelles, for their structure and stability, exchange kinetics of polymer chains or cargo, and translational properties. Greater understanding about the fundamental properties of these polymeric systems, is essential for enabling new applications and new research areas.

Conventional free radical polymerization of n-butyl acrylate with 3-[[2-(methacryloyloxy)ethyl](dimethyl)-ammonio]-1-propanesulfonate (SBMA) and 2-[butyl(dimethyl)amino]ethyl methacrylate methanesulfonate (BDMAEMA MS), respectively, yielded zwitterionomers and cationomers of comparable chemical structures. Differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and atomic force microscopy (AFM) revealed that zwitterionomers promoted more well-defined microphase-separation than cationic analogs. Dynamic mechanical analyses (DMA) of the copolymers showed a rubbery plateau region due to physical crosslinks between charges for zwitterionomers only. We attributed improved microphase-separation and superior elastomeric performance of the zwitterionomers to stronger association between covalently tethered charged pairs. Zwitterionomer / ionic liquid binary compositions of poly(nBA-co-SBMA) and 1-ethyl-3-methylimidazolium ethylsulfate (EMIm ES) were prepared using both the 'swelling– and the –cast with– methods. Dynamic mechanical analysis revealed that the 'swollen– membranes maintained their thermomechanical performance with up to 18 wt% EMIm ES incorporation, while that of the –cast with– membranes decreased gradually as the ionic liquid concentration in the composite membranes increased. Small-angle X-ray scattering results indicated that the 'swollen– and the –cast with– membranes have different morphologies, with the ionic liquid distributed more evenly inside the –cast with– membranes. Impedance spectroscopy results showed that the –cast with– membranes had better ionic conductivity than the 'swollen– membrane at high ionic liquid concentration, in agreement with our proposed model. The results indicated that the different processing methods had a significant impact on thermomechanical properties, ionic conductivities, as well as morphologies of the zwitterionomer / ionic liquid binary compositions. Reversible addition-fragmentation chain transfer polymerization (RAFT) strategy afforded the synthesis of well-defined poly(sty-b-nBA-b-sty). 2-(Dimethylamino)ethyl acrylate (DMAEA), a tertiary amine-containing acrylic monomer, exhibited radical chain transfer tendency toward itself, which is undesirable in controlled radical polymerization processes. We employed a higher [RAFT] : [Initiator] ratio of 20 : 1 to minimize the impact of the chain transfer reactions and yielded high molecular weight poly[sty-b-(nBA-co-DMAEA)-b-sty] with relatively narrow PDIs. The presence of the tertiary amine functionality, as well as their quaternized derivatives, in the central blocks of the triblock copolymers afforded them tunable polarity toward polar guest molecules, such as ionic liquids. Gravimetric measurements determined the swelling capacity of the triblock copolymers for EMIm TfO, an ionic liquid. DSC and DMA results revealed the impact of the ionic liquid on the thermal and thermomechanical properties of the triblock copolymers, respectively. Composite membranes of DMAEA-derived triblock copolymers and EMIm TfO exhibited desirable plateau moduli of ~ 100 MPa, and were hence fabricated into electromechanical transducers. RAFT synthesized poly(sty-b-nBA-b-sty) triblock copolymer phase separates into long-range ordered morphologies in the solid state due to the incompatibility between the poly(nBA) phases and the poly(sty) phases. The incorporation of DMAEA into the central acrylic blocks enabled subsequent quaternization of the tertiary amines into sulfobetaine functionalities. Both DSC and DMA results suggested that the electrostatic interactions in the low Tg central blocks of poly(sty-b-nBA-b-sty) enhanced block copolymer phase separation. SAXS results indicated that the presence of the sulfobetaine functionalities in acrylate phases increased electron density differences between the phases, and led to better defined scattering profiles. TEM results confirmed that the block copolymers of designed molecular weights exhibited lamellar morphologies, and the lamellar spacing increased with the amount of electrostatic interactions for the zwitterionic triblock copolymers. Acrylic radicals are more susceptible to radical chain transfer than their styrenic and methacrylic counterparts. Controlled radical polymerization processes (e.g. RAFT, ATRP and NMP) mediate the reactivity of the acrylic radical and enable the synthesis of well-defined linear poly(alkyl acrylate)s. However, functional groups such as tertiary amine and imidazole on acrylic monomers interfere with the controlled radical polymerization of functional acrylates. Model CFR and RAFT polymerization of nBA in the presence of triethylamine and N-methyl imidazole revealed the interference of the functional group on the polymerization of acrylate. Various RAFT agents, RAFT agent to initiator ratios, degree of polymerization and monomer feed concentrations were screened with an imidazole-containing acrylate for optimized RAFT polymerization conditions. The results suggest that the controlled radical polymerization of functional acrylates, such as 2-(dimethylamino)ethyl acrylate and 4-((3-(1H-imidazole-1-yl)propanoyl)oxy)-butyl acrylate (ImPBA), remained challenging. / Ph. D.

The goal of this work is to examine the applicability of the Lauritzen-Hoflinan (LH) surface nucleation theory to the crystallization kinetics of poly(ε-caprolactone), PCL. This theory has successfully predicted a number of experimental observations such as the temperature dependence of spherulitic growth rates and the inverse relation between undercooling and the lamellar thickness. Claims have appeared in the literature that analysis of growth rate data using the LH theory does not yield physically meaningful parameters. This work will show that the lateral and fold interfacial free energy parameters, σ and σₑ, found by analysis with the LH theory are related to the chemical structure of the polymer chain in the case of PCL. The fold interfacial free energy is related to the chain stiffness, and a recent proposal relates σ to the characteristic ratio, C_∞. This work will examine the validity of the proposed relationship for the case of PCL. The effect of polymer chain architecture on the crystallization behavior was also investigated. The crystallization behavior of poly(ε-caprolactone) was compared and contrasted to that of a triblock copolymer containing (ε-caprolactone) blocks. / Ph. D.

The dynamic characteristics of hydrogen and ionic bonding contributes to the reversible properties of acrylic polymers, opening new avenues for designing materials with mechanical strength and processability. These non-covalent interactions function as physical crosslinks, which provide enhanced structural and mechanical integrity to acrylic block copolymers. The strong hydrogen bonding or ionic interaction also directs self-assembly to hierarchical microstructures, which enables many applications including thermoplastic elastomers and energy storage devices. Inspired by complementary hydrogen bonding interactions between nucleobase pairs in DNA, a series of bioinspired nucleobase-acrylate monomers such as adenine acrylate (AdA), thymine acrylate (ThA), cytosine acrylate (CyA) were designed, whose synthesis were afforded by aza-Michael addition. Among those nucleobases, cytosine arises as a unique category. It is not only able to self-associate via weak hydrogen bonds, but also forms quadruple hydrogen-bond bearing units (ureido-cytosine) when functionalized with isocyanates. Reversible addition-fragmentation chain transfer polymerization (RAFT) yielded acrylic ABA triblock copolymers with CyA external hard blocks. A subsequent post-functionalization using hexyl-isocyanate generated the corresponding ureido-cytosine acrylate(UCyA)-containing triblock copolymers. The self-complementary quadruple hydrogen bonding in the UCyA polymers achieved a broader service temperature window, while the alkyl chain ends of UCyA units allowed tunability of the mechanical strength to apply as thermoplastic elastomers. In addition, quadruple hydrogen bonding induced stronger propensity of self-assembly and denser packing of the polymers, which contributed to a well-defined ordered morphology and enhanced resistance to moisture uptake. A facile 2-step synthesis provided doubly-charged styrenic DABCO salt monomer(VBDC₁₈BrCl) containing an octadecyl tail. RAFT polymerization allowed the preparation of DABCO ABA block copolymers with defined molecular weights and low polydispersity. Thermal analysis revealed a melting transition of the VBDC₁₈BrCl block copolymer resulting from the side-chain crystallization of the long alkyl tail. Systematic mechanical comparisons between DABCO salt-containing copolymers and the corresponding singly-charged polymer controls demonstrated superior mechanical properties attributable to a stronger ionic interaction between the doubly-charged groups. Morphological characterizations revealed a well-ordered lamellar microstructure and a unique three-phase morphology of the DABCO block copolymers, which involve a soft phase, a hard phase, and an ionic aggregates domain dispersed within the hard domain. / Master of Science

Des masques polymères à porosité contrôlée sont fabriqués à partir de films minces de copolymères à blocs auto-organisés polystyène-b-polylactide (PS-PLA) et polystyrène-b-poly(méthacrylate de méthyle) (PS-PMMA). Les films doivent être réorganisés grâce à une exposition aux vapeurs de solvant (THF ou DCE) pour obtenir des cylindres perpendiculaires à la surface, dans le volume et arrangés de façon hexagonale à longue distance. L’extraction sélective des domaines minoritaires conduit alors à des films minces poreux de PS. La mise en place de nouvelles techniques de caractérisation (analyse des images AFM, analyse MEB de répliques de système poreux, ellipso-porosimétrie) a permis d’évaluer l’influence de nombreux paramètres (nature du substrat, épaisseur du film, mode de dépôt, nature du solvant, temps et mode d’exposition aux vapeurs du solvant, …) sur la morphologie des films (surface, interface substrat/film, volume) et sur la cinétique de réorganisation. Des mélanges de copolymères à blocs A-B et d’homopolymères C (PS-PMMA/PLA, PS-PLA/PMMA, PS-PLA/PEO, PS-PEO/PLA, PS-PEO/PMMA, PS-PMMA/PEO) sont également étudiés. L’ajout d’homopolymères permet dans certains cas, d’améliorer la réorganisation des films de copolymères à blocs. Il permet également une augmentation des tailles caractéristiques du système. L’homopolymère C se localise au centre des domaines du bloc minoritaire B si χA-C> χB-C et χA-C > χA-B. Par exemple, dans le cas du mélange PS-PMMA/PLA, des cylindres perpendiculaires à la surface et organisés de façon hexagonale sont observés après exposition aux vapeurs de THF avec incorporation des domaines d’homopolymères PLA au centre des domaines de PMMA. / Polymer films with controlled porosity are obtained from block copolymer thin films of polystyrene-b-polylactide (PS-PLA) and polystyrene-b-poly(methylmethacrylate) (PS-PMMA). The morphology of these films must be reorganized by solvent annealing (THF or DCE) in order to obtain the cylinders perpendicular to the surface, in the volume and arranged in a hexagonal lattice over a long distance. The selective removal of the minority domains leads to a porous thin film of PS. New characterization techniques (AFM image analysis, SEM analysis of the silica replica, ellipsoporosimetry) are developed to evaluate the influence of various parameters (substrate nature, film thickness, method of deposition, duration and method of solvent vapors annealing …) on the morphology of the film (surface, interface and volume) and on the kinetics of reorganization. Blends of copolymer/homopolymer A-B/C (PS-PMMA/PLA, PS-PLA/PMMA, PS-PLA/PEO, PS-PEO/PLA, PS-PEO/PMMA, PS-PMMA/PEO) are also studied. In some cases, the addition of homopolymers can improve the reorganization of block copolymer films. It also allows an increase of the characteristics size of the system. Homopolymers C locate at the center of the minority B domains if χA-C> χB-C and χA-C> χA-B. For example, in the case of PS-PMMA/PLA blends, cylinders perpendicular to the surface and hexagonally arranged are observed after exposure to vapor of THF with incorporation of PLA homopolymer in central PMMA domains.

L'objectif de cette thèse est d'élaborer et de développer un type de membranes polymères qui peuvent se réparer de manière autonome en cas de fissures. Si elles ne sont pas détectées, ces fissures peuvent poser des problèmes notamment pour des applications médicales. Dans une première partie, une membrane polymère dynamique à base de micelles de copolymère tribloc ABA a été préparée. Le bloc "A" est représenté par le poly (styrene-co-acrylonitrile), copolymère bloc mécaniquement robuste, et un bloc "B" relativement mou et souple, le poly (ethylene oxide). Lorsqu'une pression est appliquée à la membrane, sa morphologie peut être ajustée grâce à la nature compressible des micelles, ainsi que les ponts dynamiques intermicellaires. Une gamme de porosités accessible peut être régulée par la pression et de manière à contrôler la performance de filtration. La même nature dynamique a également été utilisée pour montrer une réparation autonome entrainée par la pression. L'efficacité du processus de réparation dépend de la taille des fissures, de la valeur de pression et de la durée d'application de la pression. En utilisant la propriété d'auto-réparation de la membrane ci-dessus, le processus « Direct Mode Translocation » de nanoparticules a également été étudié. Quatre classes différentes de nanoparticules ont été utilisées avec diverses propriétés intrinsèques et extrinsèques. Les conclusions de ces travaux prouvent que les caractéristiques de taille, de forme et de surface des nanoparticules ainsi que la force exercée régissent le processus de translocation. Dans une seconde partie, un revêtement 2D et 3D réversible basé sur l'auto-assemblage de micelles de copolymère dibloc constitué d'un poly (methyl methacrylate) (PMMA) et du poly (n-octadecyl methacrylate) (PODMA) blocs a été développé. L'assemblage de micelles est réalisé par l'effet "Zipper", grâce aux longues chaînes pendantes du bloc PODMA. Le même effet "Zipper" permet d'enlever facilement le revêtement par lavage dans un solvant sélectif, donnant ainsi la possibilité de modifier la surface d'un substrat plusieurs fois de manière réversible. La cristallisation à température ambiante du bloc PODMA offre la possibilité d'avoir un revêtement auto-réparable thermiquement sans affecter la morphologie globale des micelles. Enfin, une dernière partie a été conceptualisée, dans laquelle l'auto-réparation se fait par « nano-gel » encapsulés et dispersés dans une membrane. Le « nano-gel » est à base d'un copolymère hydrophile en forme d'une étoile partiellement réticulée et qui doit être synthétisée par la technique de "Reversible Addition-Fragmentation Transfer" (RAFT) polymérisation. La synthèse d'un agent RAFT avec 4 bras pour la polymérisation a été accomplie, cependant, des travaux sont encore nécessaires pour valider la voie de synthèse vers la synthèse de « nano-gel » ainsi que son application pour le processus d'auto-réparation. / The objective of this thesis is to develop such kind of polymeric membranes which can repair themselves autonomously in an event of damage. Such damage in a membrane, if left undetected can pose serious health issues in some of the intended applications. In the first approach, a dynamic polymeric membrane based on ABA type triblock copolymer micelles has been prepared. The block “A” is represented by mechanically robust poly(styrene-co-acrylonitrile) copolymer while block “B” by relatively soft and flexible poly(ethylene oxide). When pressure is applied to the membrane, its morphology can be fine-tuned thanks to the compressible nature of micelles as well as intermicellar dynamic bridges. A range of porosities are accessible which can be regulated by pressure and thereby controlling the filtration performance. The same dynamic nature has also been utilized to display an effective pressure driven autonomous healing. The efficiency of healing process has been found to be dependent on the extent of damage, pressure value and time duration of application of pressure. Using the self-healing property of above membrane, “Direct Mode Translocation” of nanoparticles has also been studied. Four different classes of nanoparticles were used with varied intrinsic and extrinsic properties. The findings of the work prove that the size, shape and surface characteristics of the nanoparticles as well as the applied force govern the translocation process. In a second approach, a 2D and 3D reversible coating based on the self-assembly of micelles of diblock copolymer consisting of poly(methyl methacrylate) (PMMA) and poly(n-octadecyl methacrylate) (PODMA) blocks have been developed. The assembly of micelles is accomplished via so called “Zipper” effect, thanks to the long pendant chains of PODMA block. The same “zipper” effect plays the role of removing the coating easily by washing in a selective solvent, thus giving the ability to alter the surface of substrate for many times in reversible manner. The room temperature crystallization of PODMA block provides huge implications for a thermally assisted self-healing coating without affecting the global micelle morphology. Finally, another approach has been conceptualized in which self-healing occurs via encapsulated nano-gel dispersed within a membrane. The nano-gel is based on a partially crosslinked hydrophilic star shaped block copolymer which has to be synthesized by “Reversible Addition-Fragmentation Transfer” (RAFT) polymerization technique. The synthesis of a 4- arm RAFT agent for polymerization has been accomplished however ; a substantial amount of work is still needed to validate the synthetic route towards the nano-gel synthesis as well as its further application for the self-healing process.