Polymérisation anionique des diènes. VI. Microstructure des polybutadiène et polyisoprène par résonance magnétique protonique à 250 MHz et mécanismes de propagation

Sallé, Robert; Pham, Quang‐Tho

doi:10.1002/pol.1977.170150802

Cited by 31 publications

(4 citation statements)

References 14 publications

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“…The 1,4-polybutadiene microstructure is identified by resonance peaks at 2.1 and 5.4 ppm, while the resonances at ca. 1.8 and 5 ppm arise from material with the 1,2-polybutadiene microstructure for all materials used in the study.…”

Section: Methodsmentioning

confidence: 99%

Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions: Experiment

Juliani

Archer

2002

Macromolecules

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Relaxation dynamics of several model A 3−A−A 3 multiarm 1,4-polybutadiene melts and solutions are investigated experimentally using small amplitude oscillatory shear rheometry over a broad temperature range (−90 to +26 °C). Two rubbery plateaus are identified from loss G‘ ‘(ω) minima at low frequencies. The storage modulus in the first plateau regime is of similar magnitude to the plateau modulus G N0 of entangled linear 1,4-polybutadiene melts, and varies with multiarm solution concentration φpom as G N(φpom) = G N0 . The second low-frequency plateau modulus G N, II increases with crossbar A volume fraction φcb in nearly the manner expected for dynamics of crossbar segments in a network diluted by relaxed arms, A (i.e., G N, II ≈ G N(γpom)φcb 1+β, with β ≈ 1.3). Despite this, we find that arms exert a profound influence on crossbar dynamics well after they have relaxed. Specifically, at solution concentrations helow the threshold for arm entanglement, the zero-shear viscosity of multiarm solutions vary with φpom as η0 ∼ φpom 2.9±0.2, which is slightly weaker than expected for entangled linear polymers without contour length fluctuations. However, for these same materials the terminal time λ is found to depend more strongly than expected on solution concentration, λ ∼ φpom 2.6±0.3. At polymer concentrations above the threshold for arm entanglements, a transition to much stronger terminal property scalings with solution concentration and molecular weight are observed. In particular, for arm entanglement densities above two, the zero-shear viscosity and terminal time of multiarm solutions are exponential functions of overall polymer molecular weight and concentration.

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Section: Methodsmentioning

confidence: 99%

Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions: Experiment

Juliani

Archer

2002

Macromolecules

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“…This low molar mass and absence of significant chain entanglements allow a better understanding of the changes in mechanical properties induced by subsequent physical cross-linking. The amount of vinyl side chains (89%) and main-chain alkene bonds (11%) was determined with 1 H NMR spectroscopy …”

Section: Results and Discussionmentioning

confidence: 99%

Physically Cross-Linked Polybutadiene by Quadruple Hydrogen Bonding through Side-Chain Incorporation of Ureidopyrimidinone with Branched Alkyl Side Chains

et al. 2022

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The synthesis of a supramolecular polymer network based on ureidopyrimidinone (UPy) is demonstrated starting from a low-molecular weight polybutadiene (PB) polymer, which was modified with UPy quadruple hydrogen-bonding motifs through UV-initiated thiol–ene chemistry under ambient conditions. Here, the UPy units contain a branched alkyl side chain rather than a methyl group, as is the case in most literature examples. The sterically demanding aliphatic 2-ethylpentyl side chain was introduced to prevent stacking of the UPy dimers and to enhance the compatibility of the UPy unit with the apolar PB polymer matrix. The UPy units were grafted onto PB with different functionalization degrees yielding materials with a relatively broad range of glass transition temperatures (T g) and material properties, as evaluated by thermogravimetric analysis, differential scanning calorimetry (DSC), and dynamic mechanical thermoanalysis. Importantly, only the system with 13 mol % UPy functionalization showed some macroscopic phase separation as indicated by its partial opaque appearance, even though this was not detected by DSC. Previous reports on PB end functionalized with methyl-functional UPy revealed phase separation through DSC, indicating that the branched side chains indeed suppress the phase separation. The network dynamics were assessed by rheological measurements at different temperatures, which were subsequently fitted to the sticky Rouse model and creep experiments. We found that the sticky Rouse model satisfactorily fits the linear response of the systems in the terminal regime. However, significant discrepancy from theory still persists in the rubbery plateau regime. This deviation is attributed to the presence of structural defects in the systems. Altogether, this work demonstrates the importance of designing the supramolecular physical cross-linker unit with a branched aliphatic side chain to enhance the compatibility with the polymer matrix for the formation of supramolecular polymer networks.

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“…On the other hand, the addition mode changes from 1.4 to 3.4 mode, when a small amount of polar solvents, such as THF, 1,2-dimethoxyethane, and TMEDA, is added to the polymerization system. Thus, the added effect of polar solvents is significant in the anionic polymerization [7][8][9].…”

Section: Solventsmentioning

confidence: 99%

Anionic Addition Polymerization (Fundamental)

Ishizone

Goseki

2014

Encyclopedia of Polymeric Nanomaterials

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SynonymsAddition polymerization; Anionic polymerization; Ionic polymerization; Vinyl polymerization Definition Anionic addition polymerization is an ionic polymerization of vinyl monomers and can be categorized as a chain polymerization initiated with nucleophilic reagents, such as organolithiums, Grignard reagents, and metal alkoxides. Anionic addition polymerization proceeds with the growing chain end carrying negative charge and counter cation. The typical monomers capable of anionic addition polymerization involve vinyl monomers having electron-withdrawing groups, such as methyl methacrylate, acrylonitrile, and 2-vinylpyridine, as well as conjugated hydrocarbon monomers, such as styrene and 1,3-butadiene.

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Polymérisation anionique des diènes. VI. Microstructure des polybutadiène et polyisoprène par résonance magnétique protonique à 250 MHz et mécanismes de propagation

Cited by 31 publications

References 14 publications

Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions: Experiment

Relaxation Dynamics of Entangled and Unentangled Multiarm Polymer Solutions: Experiment

Physically Cross-Linked Polybutadiene by Quadruple Hydrogen Bonding through Side-Chain Incorporation of Ureidopyrimidinone with Branched Alkyl Side Chains

Anionic Addition Polymerization (Fundamental)

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