Local Structure And Molecular Dynamics Of Supramolecules And Semicrystalline Polymers As Investigated By Solid State Nmr

In this dissertation, we have focused on the study of the interplay of structure and molecular dynamics of soft materials including supramolecules and semicrystalline polymers at the molecular scale through various state-of-the-art solid state NMR techniques. The dissertation is consisting of three parts. In Chapter IV, we focus on the atomic scale dynamics for a Janus bisamide supramolecule. Relationship between unique structure and dynamics will be demonstrated. On the basis of the determined conformations and packing structures of the alkyl chains in ordered and disordered crystalline phases, along with the geometry and kinetic parameters of the structural elements' dynamics, the self-assembly, the phase-transition mechanisms, and the relationship between the structure and dynamics of the asymmetric Janus bisamide supramolecules were addressed.In Chapter V, we investigate molecular dynamics of semicrystalline polymers including poly-lactic acid-PLA, polyethylene oxide PEO, and polyoxymethylene POM in well controlled morphologies. Based on dynamic frequency and geometry of molecular motions, we've discussed possible structural factors that influence chain dynamics in the crystalline regions. In Chapter VI, we investigate the chain-trajectory of PLA stereocomplex by 13C Double-Quantum -DQ NMR in combination with spin-dynamics simulation. Poly-L-lactide PLLA and poly-D-lactide -PDLA alternatively pack with each other and form stereocomplex crystals (SCs). The habits of SCs formed in the dilute solution depend highly on the molecular weight Mw. It was demonstrated that the ensemble average of the successive adjacent re-entry number n for the l-PLLA chains drastically changes depending on Mws of the counter PDLA chains in the SCs. It was concluded that the limited space for two kinds of PLA chains at the fold surface significantly influence the chain-folding patterns inside the SCs and as a result led to the unique Mw dependence of the crystal morphology.

Molecular Characterization of Polymers presents a range of advanced and cutting-edge methods for the characterization of polymers at the molecular level, guiding the reader through theory, fundamentals, instrumentation, and applications, and supporting the end goal of efficient material selection and improved material performance. Each chapter focuses on a specific technique or family of techniques, including the different areas of chromatography, field flow fractionation, long chain branching, static and dynamic light scattering, mass spectrometry, NMR, X-Ray and neutron scattering, polymer dilute solution viscometry, microscopy, and vibrational spectroscopy. In each case, in-depth coverage explains how to successfully implement and utilize the technique. This practical resource is highly valuable to researchers and advanced students in polymer science, materials science, and engineering, and to those from other disciplines and industries who are unfamiliar with polymer characterization techniques. Introduces a range of advanced characterization methods, covering aspects such as molecular weight, polydispersity, branching, composition, and tacticity Enables the reader to understand and to compare the available technique, and implement the selected technique(s), with a view to improving properties of the polymeric material Establishes a strong link between basic principles, characterization techniques, and real-life applications

In polymer science and technology, the advanced development of various new polymer materials with excellent properties and functions is desirable. For this purpose it is necesary to determine the exact relationship between physical properties and molecular structure-dynamics with powerful techniques. One such technique is solid state NMR. Recently, high resolution NMR studies of solids have been realized by using advanced pulse and mechanical techniques, which has resulted in a variety of structural and dynamical information on polymer systems. Solid state NMR has provided characteristic information which cannot be obtained by other spectroscopic methods. This book is divided into two parts. The first part covers the principles of NMR, important NMR parameters such as chemical shifts, relaxation times, dipolar interactions, quadrupolar interactions, pulse techniques and new NMR methods. In the second part, applications of NMR to a variety of polymer systems in the solid state are described. Features of this book: • Contains an up-to-date and comprehensive account of solid state NMR of polymers by leading researchers in the field • Provides a compilation of solid state NMR of polymers, which makes it an ideal reference book for both NMR researchers and general polymer scientists. This book will be of interest to the NMR community, and will be invaluable for both the beginner and the expert.

The aim of the present thesis is the investigation of the structure and dynamics of rather large and complex supramolecular systems with solid-state nuclear magnetic resonance (NMR) spectroscopy. The results contribute to the understanding of structural and dynamical properties induced by pi-pi interactions in different supramolecular systems and, in this way, promote the understanding as well as the chemical design of complex self-organizing materials. Dipolar 1H-1H and 1H-13C recoupling NMR methods under fast magic angle spinning (MAS), which do not rely on isotopic labeling, enable the analysis of 1H NMR chemical shift effects as well as dipolar 1H-1H and 1H-13C couplings. In this way, site-specific information about the local structure and the segmental dynamics of different moieties in a supramolecular system is provided. In combination with nucleus independent chemical shift (NICS) maps (computed in the framework of ab-initio methods), protons can be positioned relative to pi-electron systems to suggest local arrangements of the molecules which form the supramolecular assembly. Moreover, local order parameters are selectively and precisely determined for different molecular building blocks from homo- and heteronuclear dipolar spinning sideband patterns. In this way, valuable information about structural and dynamical properties is gained, which helps to identify structure-directing elements, to quantify local interactions and to understand principal order phenomena, which altogether determine the self-assembly process of supramolecular systems.

Since Keller found single crystal of polyethylene (PE) in 1957, he first proposed the long polymer chains are more or less regularly folded in thin lamellae and the chain stems between successive folds oriented preferentially normal to the plane of the lamellae. The discovery has triggered the study of how long polymer molecules are embedded in the thin lamellae of semicrystalline polymers. Subsequently, several different crystallization mechanisms had been proposed such as Lauritzen-Hoffman kinetic theory, multistage model, aggregation model, and bundle model, etc. In order to prove these crystallization models, chain trajectory of semicrystalline polymers have been investigated prominently by neutron scattering (NS) and infrared (IR) spectroscopy combined with 1H/2H polymers because the chain-level structure would reflect the process during the crystallization. Later on, other techniques such as atomic force microscopy (AFM) and decoration method on the surface of PE crystals have been developed. Irrespective of the tremendous efforts over the last half century, the detailed chain trajectory of semicrystalline polymers still remains missing due to insufficient resolution of available techniques and intrinsic polymer structures that consist of repeating monomer units. Therefore, various crystallization theories could not be verified until now and hence a new approach is required to clarify the molecular level structure. In this dissertation, we have developed a novel strategy to investigate chain trajectory of semicrystalline polymers as a function of concentration and crystallization temperature. We have used solid-state nuclear magnetic resonance (SS-NMR) spectroscopy combined with selectively 13C isotopic labeling approach. Since the SS-NMR approach based on 13C-13C magnetically dipolar interactions has atomic level resolutions, the approach was able to investigate the chain trajectory of isotactic poly(1-butene) (iPB1). 13C-13C double quantum (DQ) NMR and spin-dynamics simulations determined adjacent re-entry parameters of the re-entrance site, chain-folding fraction (F), average successive chain-folding number n, and molecular dimension of folded chains of iPB1 with a relatively low Mw of 37 K g/mol in melt- and solution-grown crystals in a wide range of crystallization temperature (T[subscript c]). The determined chain trajectory of form I iPB1, which is one of the type of iPB1 crystal form, turned out that the re-entrance site of iPB1 is independence of the concentration and crystallization temperatures while the lower concentration induces long-range order and higher fraction of adjacent re-entry chain-folding. The n and F values were nearly invariant of T[subscript c] in each the solution- and melt-grown systems. In addition, we studied the effects of T[subscript c] on the lamellar thickness (l[subscript c]), crystallinity ([Chi][subscript c]), and morphology of iPB1 crystallized in both states. The combined data obtained at different length scales demonstrated that kinetics plays different roles for the structural formations from molecular to morphological levels. Lastly, another iPB1 form III displayed three dimensional clusters of folded chains instead of the two dimensional one expected by classical surface nucleation model of crystallization. Through the molecular level structures, [Chi][subscript c], l[subscript c], morphology of single crystal, and the dimension of folded chains as well as the molecular dynamics information reported in the literature, we discussed the crystallization mechanisms of semicrystalline polymer from a molecular level of view.

Advances in Polymer Science enjoys a longstanding tradition and good reputation in its community. Each volume is dedicated to a current topic, and each review critically surveys one aspect of that topic, to place it within the context of the volume. The volumes typically summarize the significant developments of the last 5 to 10 years and discuss them critically, presenting selected examples, explaining and illustrating the important principles, and bringing together many important references of primary literature. On that basis, future research directions in the area can be discussed. Advances in Polymer Science volumes thus are important references for every polymer scientist, as well as for other scientists interested in polymer science - as an introduction to a neighboring field, or as a compilation of detailed information for the specialist.

The progress in polymer science is revealed in the chapters of Polymer Science: A Comprehensive Reference, Ten Volume Set. In Volume 1, this is reflected in the improved understanding of the properties of polymers in solution, in bulk and in confined situations such as in thin films. Volume 2 addresses new characterization techniques, such as high resolution optical microscopy, scanning probe microscopy and other procedures for surface and interface characterization. Volume 3 presents the great progress achieved in precise synthetic polymerization techniques for vinyl monomers to control macromolecular architecture: the development of metallocene and post-metallocene catalysis for olefin polymerization, new ionic polymerization procedures, and atom transfer radical polymerization, nitroxide mediated polymerization, and reversible addition-fragmentation chain transfer systems as the most often used controlled/living radical polymerization methods. Volume 4 is devoted to kinetics, mechanisms and applications of ring opening polymerization of heterocyclic monomers and cycloolefins (ROMP), as well as to various less common polymerization techniques. Polycondensation and non-chain polymerizations, including dendrimer synthesis and various "click" procedures, are covered in Volume 5. Volume 6 focuses on several aspects of controlled macromolecular architectures and soft nano-objects including hybrids and bioconjugates. Many of the achievements would have not been possible without new characterization techniques like AFM that allowed direct imaging of single molecules and nano-objects with a precision available only recently. An entirely new aspect in polymer science is based on the combination of bottom-up methods such as polymer synthesis and molecularly programmed self-assembly with top-down structuring such as lithography and surface templating, as presented in Volume 7. It encompasses polymer and nanoparticle assembly in bulk and under confined conditions or influenced by an external field, including thin films, inorganic-organic hybrids, or nanofibers. Volume 8 expands these concepts focusing on applications in advanced technologies, e.g. in electronic industry and centers on combination with top down approach and functional properties like conductivity. Another type of functionality that is of rapidly increasing importance in polymer science is introduced in volume 9. It deals with various aspects of polymers in biology and medicine, including the response of living cells and tissue to the contact with biofunctional particles and surfaces. The last volume is devoted to the scope and potential provided by environmentally benign and green polymers, as well as energy-related polymers. They discuss new technologies needed for a sustainable economy in our world of limited resources. Provides broad and in-depth coverage of all aspects of polymer science from synthesis/polymerization, properties, and characterization methods and techniques to nanostructures, sustainability and energy, and biomedical uses of polymers Provides a definitive source for those entering or researching in this area by integrating the multidisciplinary aspects of the science into one unique, up-to-date reference work Electronic version has complete cross-referencing and multi-media components Volume editors are world experts in their field (including a Nobel Prize winner)

Physical techniques such as X-ray crystallography, IR spectroscopy and solution-phase NMR spectroscopy have played key roles in the development of supramolecular chemistry. In recent years other spectroscopic techniques have been applied, expanding the range of information obtainable. The most widely used technique is solid-state NMR spectroscopy but techniques such as neutron scattering and NQR spectroscopy can yield significant information. Computational approaches are now becoming powerful complementary methods to experimental techniques and this book reviews the application of these methods to supramolecular systems. The ten chapters provide up-to-date information on the applications of spectroscopic and computational techniques to a wide range of supramolecular systems: Solid State NMR Studies of Host-Guest Materials Infrared Studies of Zeolite Complexes NQR Studies of Inclusion Compounds Neutron Scattering Studies of Zeolite Complexes Solid State NMR Studies of Catalytic Reactions on Molecular Sieves Recent Advances in Computational Studies of Zeolites Theoretical Studies of Cyclodextrins and their Inclusion Complexes Computer Modelling of the Structures of Host-Guest Complexes Computational Studies of Clathrate Hydrates Ab initio Electronic Structure Calculations on Endohedral Complexes of the C60 Cluster. This timely book will prove to be of great value to supramolecular researchers who are familiar with the spectroscopic techniques but who wish to extend their knowledge of the computational methods (and vice versa), to supramolecular researchers working in allied areas whose work would benefit from applying spectroscopic and computational methods, and finally to workers just entering the fascinating area of supramolecular chemistry.