No description available.

No description available.

Supramolecular polymers represent a family of polymeric materials that are held together with dynamic, noncovalent interactions. In contrast to conventional functional polymers that usually have high melt-viscosity due to their covalent nature and chain entanglement, supramolecular polymers combine excellent physical properties with low melt-viscosity, allowing for less energy-intensive processability and recyclability. Dynamic bonding with multiple binding sites, such as multiple hydrogen bonding or multiple ionic bonding, exhibits much stronger binding strength compared to the counterparts containing only a single binding site, thereby allowing for enhanced mechanical integrity to the polymers and facilitate self-assembly. This dissertation focuses on the design of novel supramolecular polymers building from the doubly-charged or quadruple hydrogen bonding (QHB) scaffolds utilizing chain-growth polymerization or step-growth polymerization, as well as elucidate the structure-property-morphology relationships of the polymers. A 2-step nucleophilic substitution reaction afforded a series of 1,4-diazabicyclo[2.2.2]octane (DABCO)-based styrenic monomers with two pairs of charged groups. An optimized 2-step reversible-addition-fragmentation chain-transfer (RAFT) polymerization synthesized ABA triblock thermoplastic elastomers (TPEs) with a low Tg poly (n-butyl acrylate) central block and a high Tg external charged blocks. Strong ionic interactions between doubly-charged units drove molecular self-assembly to form densely packed, hierarchical microstructures, which contributed to a robust, crosslinked physical network that allows the polymer to retain thermomechanical integrity until degradation. High-resolution single-crystal X-ray diffraction (SCXRD) coupled with powder X-ray diffraction (PXRD) further disclosed a detailed 3-D structural information of molecular arrangement and ion distribution within the charged phase through comparing DABCO-salt monomer single-crystal structure and the corresponding homopolymer XRD pattern. It was found that the physical properties of the DABCO-salt copolymers not only relied on their charge content and architectures but also dependent on their electrostatically-bonded counterions. The size and structure of the counterion determined the strength of dipole-dipole interaction, which significantly impact on thermal property, (thermo)mechanical performance, water affinity, and microstructure. A cytosine-functionalized monomer, cytosine acrylate (CyA), allowed the synthesis of acrylic ABA triblock TPEs with pendant nucleobase moieties in the external blocks and a low Tg central polymer matrix through RAFT polymerization. Post-functionalization of cytosine (Cyt) bidentate hydrogen bonding sites with alkyl isocyanate, allowed the formation of ureido-cytosine (UCyt) groups in the external block that were readily dimerized through QHB interactions. The UCyt units in the external block enhanced mechanical strength and induced stronger phase-separation of the block copolymers compared to the corresponding Cyt-containing TPE analogs. Facile conventional free-radical polymerization using CyA and subsequent post-functionalization enabled accessibility to random copolymers containing pendant UCyt QHB moieties in the soft polymer matrix. The synergy of the flexible polymer matrix and the dynamic character of QHB groups contributed to the ultra-high elasticity of the polymer and rapid self-healing properties. QHB interactions enabled efficient mechanical recovery upon deformation by facilitating elastic chain retraction to regenerate the original physical network. Finally, one-pot step-growth polymerization through chain extending a novel bis-Cyt monomer and a commercially available polyether diamine using a di-isocyanate extender afforded segmented polyurea series for extrusion additive manufacturing. The molecular design of the polyureas featured soft segments containing flexible polyether chain and a relatively weak urea hydrogen bonding sites in the soft segment and rigid UCyt hydrogen bonding groups in the hard segment. The reversible characteristics of QHB enabled low viscosity at the processing temperature while providing mechanical integrity after processing and reinforced bonding between the interlayers, which contributed to the remarkable strength, elasticity, toughness, and interlayer adhesion of the printed parts. / Doctor of Philosophy / This dissertation focuses on designing supramolecular thermoplastic elastomers containing strong noncovalent interactions, i.e., quadruple hydrogen bonds or double ionic bonds. Inspired from noncovalent interactions in our mother nature, a series of bio-inspired monomers functionalized with nucleobase or ionic units were synthesized through scalable reactions with minimal purification steps. Polymerization of the functional monomers through step-growth or chain-growth polymerization techniques affords a variety of supramolecular thermoplastic elastomers with well-defined structures and architectures. These thermoplastic elastomers comprise soft and hard constituents; the former contains low glass transition polymer chains that provide elasticity while the latter contains strong noncovalent units to impart mechanical strength. Varying the soft/hard component ratios enables polymers with tunable physical properties to address different needs. Systematic characterizations of these supramolecular polymers revealed their distinct properties from the polymers containing the covalent or weak noncovalent interactions and facilitate molecular-level understanding of the polymers. Generally, incorporating strong noncovalent interactions increases the temperature for polymer segmental motion and extends thermomechanical plateau windows. Additionally, the strong association strength of those non-covalent interactions promotes microphase separation and self-assembly, contributing to a high degree of structural ordering of the polymers. Moreover, the dynamic characteristics of the noncovalent interactions offer the polymers with reversible properties, which not only enables melt-processability and recyclability of the polymer but also contributes to a series of smart properties, including self-healing, shape-memory, and recoverability. Thus, the molecular design using supramolecular chemistry provides promising avenues to developing functional materials with enhanced mechanical properties, processability, and stimuli-responsiveness for emerging applications.

Die vorliegende Arbeit beinhaltet Studien zur Darstellung, Charakterisierung und Reaktivität von Platin-Fluorido-Komplexen, die 2-(3-Methyl)indolyl-substituierte Phosphan-Liganden besitzen, welche über die Indolyl-Einheiten Wasserstoffbrückenbindungen zu Fluorido-Liganden oder Poly(hydrogenfluorid)¬fluorid-Anionen in der äußeren Ligandensphäre ausbilden. Die Darstellung der Platin-Fluorido-Komplexe gelang dabei über zwei verschiedene Syntheserouten. Die Reaktion von Chlorido-Vorläuferkomplexen mit Tetramethylammoniumfluorid führte zur Deprotonierung der Indolyl-NH-Protonen und einer damit verbundenen Cyclometallierung der Phosphan-Liganden am Platinzentralmetall. Bei Zugabe von Fluorwasserstoff-Quellen erfolgte die Bildung eines Platin-Fluorido-Komplexes, mit dem die Aktivierung von CO zu einem Carbamoyl-Komplex sowie von einem Inamid zu einem ungewöhnlichen Oxazol-Derivat gelang. Eine weitere Möglichkeit zur Darstellung von Platin-Fluorido-Komplexen eröffnete sich durch die Reaktion von Platin-Methyl-Verbindungen mit HF-Quellen. Hierbei bildeten sich Fluorido-Komplexe, bei denen die beiden trans-ständigen Indolylphosphan-Liganden intramolekulare Wasserstoffbrücken zum platingebundenen Fluoratom aufbauen. Die Identität der Fluorido-Komplexe wurde mittels 1H-, 19F , 31P{1H}- sowie 1H,15N-HMBC-NMR-Spektroskopie, IR-Spektroskopie sowie teilweise durch Röntgenstrukturanalysen untersucht. Durch gezielte Veränderungen des zum Fluorido-Liganden trans-ständigen Aryl-Liganden konnten zudem die Struktur-Eigenschafts-Beziehungen näher ermittelt werden. Die Existenz der Wasserstoffbrücken in der äußeren Koordinationssphäre zum Fluorido-Liganden ermöglichte bisher beispiellose Reaktivitäten. So wurde in Modellreaktionen die elektrophile Aktivierung von Alkinen bei gleichzeitiger Bereitstellung des dissoziierten Fluorido-Liganden in der äußeren Koordinationssphäre beobachtet. Hierauf basierend wurden selektive, katalytische Umsetzungen von Alkinen zu (Z)-Fluoralkenen entwickelt. / Studies on the formation, characterisation and reactivity of platinum fluorido complexes bearing 2-(3-methyl)indolyl substituted phosphine ligands, which allow for the generation of hydrogen bonding to the fluorido ligand as well as polyfluorides in the outer coordination-sphere are presented. The formation of the platinum fluorido complexes was achieved by two different synthetic routes. Using tetramethylammonium fluoride (TMAF) for an Cl/F exchange at chlorido precursor complexes led to the formation of cyclometallated platinum complexes due to deprotonation of the indolyl NH group of the phosphine ligands. Treatment of the cyclometallated complex with HF-sources led to the formation of a platinum fluorido compound, which was applied in the electrophilic activation of carbon monoxide as well as an ynamide generating a carbamoyl complex and an exceptional metal bound oxazole derivative, respectively. Additionally, platinum fluorido complexes were accessible through protonation of methyl ligands of suitable precursor complexes. Using this route, fluorido complexes bearing trans coordinated indolylphosphine ligands are formed, which allow for the generation of two hydrogen bonds to the fluorido ligand. The structure of the fluorido complexes were analysed by 1H-, 19F-, 31P{1H}- and 1H,15N-HMBC NMR data, IR-spectroscopy and in part by single crystal X-ray diffraction. Variation of the aryl ligands in a mutually trans position to the platinum bound fluorine atom gave an insight on the structure-property relationships of the fluorido complexes. The existence of outer-sphere hydrogen bonding to the fluorido ligands allowed for unprecedented reactivities. Thus, model reactions revealed complexes bearing a pendant fluoride in the coordination sphere while at the same time an alkyne is activated at the platinum centre. Based on this, catalytic hydrofluorination reactions of unactivated alkynes to provide selectively (Z)-fluoroalkenes were developed.

Powerful spectroscopic techniques increasingly involve nonlinear processes that arise due to the convolution of more than one electric field - input laser pulse. Analyzing the output of optical processes like these demands the utilization of deterministic improvement tools. Three-color coherent Raman scattering represents a complex non-degenerate four wave mixing process that includes contributions from both resonant and non-resonant interaction of the three input fields to generate a signal. In order to quantify these contributions, effective differentiation of the non- resonant (background) from the resonant (coherent signal) is required. These contributions can be differentiated based on how the molecular vibrational modes are being excited by the input pulses. The work described here demonstrates the ability of second-order correlation spectroscopy, applied along with an all-Gaussian theoretical model to analyze three color coherent Raman scattering processes. It is shown to discriminate between resonant versus non-resonant four wave mixing processes successfully. A robust, femtosecond/picosecond coherent Raman spectroscope is used to observe how the resonant signal builds up in a finite amount of time for different specimens and how it is can be controlled by input laser pulse shaping. A closed-form solution obtained via an all-Gaussian approach provides confirmatory theoretical proof of the experimental results obtained. This technique is used to study hydrogen bonding, which is a vital molecular interaction for bio-molecular systems and yet lacks a profound understanding of its ways of forming complexes. Furthermore, a novel second-order one-dimensional correlation function is introduced that replicates the results of the diagonal sum of the traditional synchronous two- dimensional correlation function, thus reducing a two-dimensional analysis to one-dimension. Along with the first demonstration of these analyses for coherent Raman scattering, a generalized approach is described, which opens up research opportunities to investigate these optical processes' dependence on multiple controlling parameters.

No description available.

No description available.

No description available.

No description available.

<p>The phase behavior of AB diblock copolymers mixed with C homopolymers (AB/C), in which A and C are capable of forming hydrogen-bonds, is examined using self-consistent field theory. The study focuses on the modeling of hydrogen-bonding in polymers. Specifically, we examine two models for the formation of hydrogen-bonds between polymer chains. The first commonly used model assumes a large attractive interaction parameter between the A/C monomers. This model reproduces correct phase transition sequences as compared with experiments, but it fails to correctly describe the change of lamellar spacing induced by the addition of the C homopolymers. The second model is based on the fact that hydrogen-bonding leads to A/C complexation. We show that the interpolymer complexation model predicts correctly the order-order phase transition sequences and the decrease of lamellar spacing for strong hydrogen-bonding. Our analysis demonstrates that hydrogen-bonding of polymers should be modeled by interpolymer complexation.</p> / Master of Science (MSc)