Microstructure of Crystallizable α-Olefin Molecular Bottlebrushes: Isotactic and Atactic Poly(1-octadecene)
| Autor: | Jarod M. Younker, Joseph A. Throckmorton, John R. Hagadorn, Carlos R. López-Barrón, Andy H. Tsou, Jonathan J. Schaefer, Alexander I. Norman |
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| Rok vydání: | 2018 |
| Předmět: |
Materials science
Polymers and Plastics Scattering Organic Chemistry 02 engineering and technology Neutron scattering 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Inorganic Chemistry Crystallography Molecular dynamics symbols.namesake Polymerization Tacticity Materials Chemistry Side chain symbols Orthorhombic crystal system 0210 nano-technology Raman spectroscopy |
| Zdroj: | Macromolecules. 51:872-883 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/acs.macromol.7b02524 |
| Popis: | Isotactic and atactic poly(1-octadecene) (iPOD and aPOD) have been synthesized by organometallic coordinative insertion polymerization of 1-octadecene. Analyzing X-ray and neutron scattering data of POD melts identifies their bottlebrush structures as flexible rods where the rod length is the extended backbone length and rod radius is the side chain coil dimension. Upon cooling, both iPOD and aPOD melts crystallize by fully extending their coiled side chains to form orthorhombic alkane crystals in iPOD and nematically ordered rotator alkane crystals in aPOD, as determined by X-ray scattering and Raman spectroscopy. Molecular dynamics simulations of isotactic and atactic 48-mers of 1-octadecene were applied to define and verify melt and crystalline structures and scattering peak assignments, respectively. Modeling suggests that side chains of both crystallized isotactic and atactic PODs align at 70° and 160° to the 4/1 spiral backbone of equal probability, at an average of 115°, and POD chains pack in an a... |
| Databáze: | OpenAIRE |
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