Glass transition temperature and chain flexibility of 1,2‐polybutadiene

He, Tianbai; Li, Bincai; Ren, Shoujing

doi:10.1002/app.1986.070310311

Cited by 18 publications

(7 citation statements)

References 18 publications

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“…The value obtained by observation of the diffraction pattern is approximately 250 K, in relative agreement with previously reported values [41][42][43] and the DSC measurements. In Figure 6, the width of the second interchain peak can be seen.…”

Section: Neutron Scatteringsupporting

confidence: 91%

Experimentally driven atomistic model of 1,2 polybutadiene

Gkourmpis

Mitchell

2014

Journal of Applied Physics

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Absence of annealing effect in the vibrational density of states in a glassforming polymerWe present an efficient method of combining wide angle neutron scattering data with detailed atomistic models, allowing us to perform a quantitative and qualitative mapping of the organisation of the chain conformation in both glass and liquid phases. The structural refinement method presented in this work is based on the exploitation of the intrachain features of the diffraction pattern and its intimate linkage with atomistic models by the use of internal coordinates for bond lengths, valence angles, and torsion rotations. Atomic connectivity is defined through these coordinates that are in turn assigned by pre-defined probability distributions, thus allowing for the models in question to be built stochastically. Incremental variation of these coordinates allows for the construction of models that minimise the differences between the observed and calculated structure factors. We present a series of neutron scattering data of 1,2 polybutadiene at the region 120-400 K. Analysis of the experimental data yields bond lengths for CAC and C @ C of 1.54 Å and 1.35 Å , respectively. Valence angles of the backbone were found to be at 112 and the torsion distributions are characterised by five rotational states, a three-fold trans-skew6 for the backbone and gauche6 for the vinyl group. Rotational states of the vinyl group were found to be equally populated, indicating a largely atactic chan. The two backbone torsion angles exhibit different behaviour with respect to temperature of their trans population, with one of them adopting an almost all trans sequence. Consequently, the resulting configuration leads to a rather persistent chain, something indicated by the value of the characteristic ratio extrapolated from the model. We compare our results with theoretical predictions, computer simulations, RIS models and previously reported experimental results. V C 2014 AIP Publishing LLC. [http://dx.

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Section: Neutron Scatteringsupporting

confidence: 91%

Experimentally driven atomistic model of 1,2 polybutadiene

Gkourmpis

Mitchell

2014

Journal of Applied Physics

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“…TGA thermographs of all the synthesized hybrid materials.The glass transition temperatures (T g s) of the components, as well as the potential mixing between the chemically dissimilar blocks, were identified from DSC experiments. In the samples PI 3,4/1,2 -b-P(o-Bn-L-Tyr) and PB 1,2 -b-P(o-Bn-L-Tyr), the T g s are expected at temperatures equal to −30 • for the PI 3,4 (~55-60%) segment while for PB 1,2 at approximately 0 • C, as already thoroughly reported in the literature[44,45,49,50]. The remaining polydienes, namely PI 1,4 (in PI 1,4 -b-P(o-Bn-L-Tyr)) and PB 1,4 )in PB 1,4 -b-P(o-Bn-L-Tyr)) display lower T g s, at approximately −70 • and −90 • , respectively [51-53].In Figure6, the DSC thermographs corresponding to the second heating of all four different samples are presented.…”

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confidence: 80%

Synthesis, Characterization and Structure Properties of Biobased Hybrid Copolymers Consisting of Polydiene and Polypeptide Segments

et al. 2021

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Novel hybrid materials of the PB-b-P(o-Bn-L-Tyr) and PI-b-P(o-Bn-L-Tyr) type (where PB: 1,4/1,2-poly(butadiene), PI: 3,4/1,2/1,4-poly(isoprene) and P(o-Bn-L-Tyr): poly(ortho-benzyl-L-tyrosine)) were synthesized through anionic and ring-opening polymerization under high-vacuum techniques. All final materials were molecularly characterized through infrared spectroscopy (IR) and proton and carbon nuclear magnetic resonance (1H-NMR, 13C-NMR) in order to confirm the successful synthesis and the polydiene microstructure content. The stereochemical behavior of secondary structures (α-helices and β-sheets) of the polypeptide segments combined with the different polydiene microstructures was also studied. The influence of the α-helices and β-sheets, as well as the polydiene chain conformations on the thermal properties (glass transition temperatures, thermal stability, α- and β-relaxation) of the present biobased hybrid copolymers, was investigated through differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy (DS). The obtained morphologies in thin films for all the synthesized materials via atomic force microscopy (AFM) indicated the formation of polypeptide fibrils in the polydiene matrix.

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“…[16,43] Similar effect has been observed in poly (methyl methacrylate) films on Au. [19,43] Flexibility of polymer chain [2,10,44,45] Some polymers show high Tg and some show low because of the ease with which the polymer chains move. A very low Tg will be shown by the polymer chains which can move around easily, while one that doesn't move will have a high Tg.…”

Section: Plasticizermentioning

confidence: 99%