Elucidation Of Chain Folding Structure Of Isotactic Poly3 Methyl Butene 1 In Bulk And Single Crystals By Solid State Nmr

Since the discovery of single crystals of polyethylene by Keller using transmission electron microscopy (TEM)1, various methods have been developed to unravel detailed chain-level structures (chain-folding) of semi-crystalline polymers in both bulk and single crystals. Nevertheless, understanding of molecular structure basis, is still a controversial issue due to experiment limitations. Such experimental situations are largely different from theory or simulations. Recently, our group developed a unique approach, which can investigate the chain trajectory of the synthetic polymer in bulk crystals, using 13C-13C double quantum (DQ) NMR combined with 13C labeling samples2. In this thesis, we propose systematic research on chain-level structure of a semi-crystalline polymer prepared under different conditions. We investigated chain-trajectory of 13C CH3-labeled isotactic poly(3-methyl-butene-1) (iP3MB1) in melt-grown crystals and solution-grown single crystals blended with non-labeled iP3MB1 using solid-state NMR. Comparisons of 13C-13C double quantum (DQ) NMR results with spin dynamics simulation revealed individual chains in melting grown crystals fold in three different directions and chains in single crystals prefer direction parallel to the long side (crystallographic a axis) of the rectangle-size single crystal is determined.

Semi-crystalline polymers undergo drastic structural changes from random coils in the melt states to folded chains in the crystalline lamellae during crystallization. One fundamental question in this process is the long-standing controversy about the chain-folding structures in semi-crystalline polymers. The isotactic polypropylene (iPP) is one of the most important polymer materials in commercial application as well as in academic field. Also, the iPP has different crystalline forms, in which the chain packing structures, such as fraction of different forms and spatial heterogeneity, were not fully understood previously. When cooled from melt, iPP crystallize into a form, which can be further divided into ordered a2 and disordered a1 depending on the methyl group orientations. Using modern high-resolution solid-state NMR (SS-NMR), the chain-packing structure of a1 and a2 forms can be quantitatively separated by the dramatic lineshape differences. The effects of chemical structures of iPP on the chain-packing structure in the crystalline region have been studied. The higher stereo regularity sample forms more a2 form at Tc > 135 oC. Moreover, 1H spin diffusion experiments indicated that the a1 and a2 form will form domain structures at average side of ca. 40 nm when iPP crystallized at 150 oC Furthermore, high-resolution NMR spectra demonstrated that the stereo regularity defects are excluded in the crystalline region at Tc = 150 oC, whereas 4% of the defect remains in the crystalline region quench annealed a1 form. Finally, the chain-folding structures and ensemble average of successive chain-folding number are revealed by 13C-13C double quantum (DQ) NMR. The average chain-folding number is determined to be 5 to 7 for both a1 and a2 forms. However, different chain-folding structures are concluded based on the chain-packing structures and conformational constrains. Through obtained packing and folding structures, crystallization mechanism was discussed at molecular levels.

In this work, we mainly studied the molecular dynamics of polyoxymethylene in fully extended single crystals (whiskers) and folded lamellae by using the solid-state NMR (SSNMR). It was found that spin lattice relaxation time in the laboratory frame (T1[subscript ,H]) in the latter is 1.5 s at 298 K while the former shows 80.3 s. The reason for the ultra-long relaxation time was attributed to the perfect crystals with the fully extended chains. And the length of the POM whisker chains was determined to be around 20 [micrometers] by Transmission Electron Microscopy. The copper (II) acetylacetonate (CuAA) was used to shorten the T1[subscript ,H] values down to 5.9 s. Crystallinity of POM whisker crystals ([Chi]c = ~100 %) and POM lamellar crystals ([Chi]c = 63.25 %) was determined by 13C direct polarization and magic angle spinning (DP/MAS) spectrum. Centerband-only Detection of Exchange (CODEX) experiment was conducted to study the slow molecular dynamics of POM whisker crystals and folded lamellae at various temperatures. The correlation time in the former was much longer than the latter. The activation energy E[subscript a] (97 [plus or minus] 4kJ/mol) of POM lamellar crystal was slightly larger than that of the POM whisker crystal (60 [plus or minus] 5kJ/mol). The lower E[subscript a] value suggested that the whisker crystals have better thermal stability than that for the folded crystals.

1. T. Takata, N. Kihara, Y. Furusho: Polyrotaxanes and Polycatenanes: Recent Advances in Syntheses and Applications of Polymers Comprising of Interlocked Structures.- 2. M. Suginome, Y. Ito: Transition Metal-Mediated Polymerization of Isocyanides.- 3. K. Osakada, D. Takeuchi: Coordination Polymerization of Dienes, Allenes and Methylenecycloalkanes.

In the context of polymer crystallization there are several still open and often controversially debated questions. The present volume addresses issues such as novel general views and concepts. It presents new ideas in a connected and accessible way. The intention is thus not only to provide a summary of the present state-of-the-art to all active works but to provide an entry point to newcomer and graduate students entering the field.

Properties of Polymers: Their Correlation with Chemical Structure; Their Numerical Estimation and Prediction from Additive Group Contributions summarizes the latest developments regarding polymers, their properties in relation to chemical structure, and methods for estimating and predicting numerical properties from chemical structure. In particular, it examines polymer electrical properties, magnetic properties, and mechanical properties, as well as their crystallization and environmental behavior and failure. The rheological properties of polymer melts and polymer solutions are also considered. Organized into seven parts encompassing 27 chapters, this book begins with an overview of polymer science and engineering, including the typology of polymers and their properties. It then turns to a discussion of thermophysical properties, from transition temperatures to volumetric and calorimetric properties, along with the cohesive aspects and conformation statistics. It also introduces the reader to the behavior of polymers in electromagnetic and mechanical fields of force. The book covers the quantities that influence the transport of heat, momentum, and matter, particularly heat conductivity, viscosity, and diffusivity; properties that control the chemical stability and breakdown of polymers; and polymer properties as an integral concept, with emphasis on processing and product properties. Readers will find tables that give valuable (numerical) data on polymers and include a survey of the group contributions (increments) of almost every additive function considered. This book is a valuable resource for anyone working on practical problems in the field of polymers, including organic chemists, chemical engineers, polymer processers, polymer technologists, and both graduate and PhD students.

The series Topics in Current Chemistry presents critical reviews of the present and future trends in modern chemical research. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field. Review articles for the individual volumes are invited by the volume editors. Readership: research chemists at universities or in industry, graduate students.

This book provides an introduction to this exciting and relativelynew subject with chapters covering natural and synthetic polymers,colloids, surfactants and liquid crystals highlighting the many andvaried applications of these materials. Written by an expert in thefield, this book will be an essential reference for people workingin both industry and academia and will aid in understanding of thisincreasingly popular topic. Contains a new chapter on biological soft matter Newly edited and updated chapters including updated coverageof recent aspects of polymer science. Contain problems at the end of each chapter to facilitateunderstanding

How can a scientist or engineer synthesize and utilize polymers to solve our daily problems? This introductory text, aimed at the advanced undergraduate or graduate student, provides future scientists and engineers with the fundamental knowledge of polymer design and synthesis to achieve specific properties required in everyday applications. In the first five chapters, this book discusses the properties and characterization of polymers, since designing a polymer initially requires us to understand the effects of chemical structure on physical and chemical characteristics. Six further chapters discuss the principles of polymerization reactions including step, radical chain, ionic chain, chain copolymerization, coordination and ring opening. Finally, material is also included on how commonly known polymers are synthesized in a laboratory and a factory. This book is suitable for a one semester course in polymer chemistry and does not demand prior knowledge of polymer science.

Cyclic Polymers (Second Edition) reviews the many recent advances in this rapidly expanding subject since the publication of the first edition in 1986. The preparation, characterisation, properties and applications of a wide range of organic and inorganic cyclic oligomers and polymers are described in detail, together with many examples of catenanes and rotaxanes. The importance of large cyclics in biological chemistry and molecular biology is emphasised by a wide coverage of circular DNA, cyclic peptides and cyclic oligosaccharides and polysaccharides. Experimental techniques and theoretical aspects of cyclic polymers are included, as well as examples of their uses such as ring opening polymerisation reactions to give commercially important materials. This book covers a wide range of topics which should be of interest to many scientific research workers (for example, in polymer science, chemistry and molecular biology), as well as providing a reference text for undergraduate and graduate students.