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Results for “Polymer science”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Role of Side-Chain Architecture in Poly(ethylene oxide)-Based Copolymers
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Polymer Crystallization under Confinement by Well-Dispersed Nanoparticles
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Elucidating the Role of Fluorine Content on Gas Sorption Properties of Fluorinated Polyimides
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Synthesis and Aqueous Self-Assembly of ABCD Bottlebrush Block Copolymers
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Polymer Spherulitic Growth Kinetics Mediated by Nanoparticle Assemblies
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Interfacial Compatibilization in Ternary Polymer Nanocomposites: Comparing Theory and Experiments
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Cu-Catalyzed Atom Transfer Radical Polymerization in the Presence of Liquid Metal Micro/Nanodroplets
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Quantification of Interactions at the Polymer–Substrate Interface: Implications for Nanoscale Behavior
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Quantifying Polypeptoid Conformational Landscapes through Integrated Experiment and Simulation
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Evolution of Chain Dynamics and Oxidation States with Increasing Chain Length for a Donor–Acceptor-Conjugated Oligomer Series
While it is known that the chain length strongly affects the properties of π-conjugated polymers, the effects of chain length on the molecular structure, chain conformation, and oxidation state properties in donor–acceptor-type conjugated structures remain unclear. This limits our understanding of how the polymer molecular weight impacts material properties. Here, a discrete and monodisperse oligomer series (n = 3, 5, 7, 9, 15, and 21) and polymers (nPB), composed of the donor 3,4-propylenedioxythiophene (ProDOT), the acceptor benzothiadiazole (BTD), and methylthio end-capping groups, are synthesized by C–H-activated cross-coupling. The molecular structure, molecular weight, and dispersity of each oligomer/polymer are thoroughly characterized by nuclear magnetic resonance spectroscopy, mass spectrometry, and gel permeation chromatography. This series reveals a rod-to-coil transition at n = 15 and coil formation at polymer length scales of ~28 units via solution small-angle neutron scattering characterization. The oxidation states are deciphered via cyclic voltammetry, differential pulse voltammetry, spectroelectrochemistry, and density functional theory calculations. Oligomers 3–9 undergo successive one-electron oxidation steps, while 15 and higher undergo multielectron oxidations per step in CH 2 Cl 2 –TBAPF6 at a Pt ultramicroelectrode. The electronic transition of each oxidation state (1+, 2+, 3+, etc.) is tracked by absorption spectroscopy, revealing a “bipolaron to di-polaron” transition at n = 7 at which shorter oligomers prefer bipolaron formation and longer oligomers prefer di-polaron formation in their dication states. Furthermore, oxidized 15 has a lower electronic transition energy compared to its polymer homologue, as shown by spectroelectrochemistry, revealing a synergy between the chain length and the oxidation state properties. This study proves that the convergence limit between small molecule and polymer behavior occurs at approximately 15 units and highlights the property transitions that occur as a function of chain length for a donor–acceptor class of conjugated organic materials.
Are RAFT and ATRP Universally Interchangeable Polymerization Methods in Network Formation?
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