Conformational features of bisphenol-A polycarbonate

Sundararajan, P. R.

doi:10.1139/v85-018

Cited by 21 publications

(13 citation statements)

References 15 publications

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“…In the preferred trans state of the carbonate group, the energy profile with the phenyl rotation I) is nearly flat with the maximum barrier of only 0.72 kcal/mol when the phenyl plane is coplanar with the carbonate group (I) = 0). =[;I (4) (5) for the type -2, -3, and -4 bonds, respectively, where y is the statistical weight for the cis conformation of the carbonate group. 1.68 kcal/mol according to the STO-3G basis set calculations for diphenyl carbonate.…”

Section: Unperturbed Chain Dimensionsmentioning

confidence: 99%

Chain conformations of polycarbonate from ab initio calculations

Laskowski¹,

Yoon²,

McLean³

et al. 1988

Macromolecules

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1629(2) Shibaev, V. P.; Plate, N. A.; Freidzon, Y. S. J . Polym. Sci., Polym. Chem. Ed. 1979,17, 1655. (3) Dubault, A.; Ober, R.; Veyssie, M.; Cabane, B. J. Phys. (Les Ulis, Fr.) 1985, 46, 1227. (4) Kirste, R. G.; Ohm, H. G. Makromol. Chem., Rapid Commun. 1985, 6, 179. (5) Keller, P.; Carvalho, B.; Cotter, J. P.; Lambert, M.; Moussa, D. Reidel: Dodrecht, 1985. F.; Pepy, G. J. Phys., Lett. 1985, 46, 1065. (6) Boeffel, C.; Spiess, H. W.; Hisgen, B.; Ringsdorf, H.; Ohm, H.; Kirste, R. G. (15) Hentschel, R.; Schlitter, J.; Sillescu, H.; Spiess, H. W.ABSTRACT: Ab initio calculations with full geometry optimization on diphenyl carbonate (DPC) and diphenylpropane (DPP) are carried out to determine the bond geometries and the conformational energies and then to compute the unperturbed chain dimensions of the polycarbonate of 2,2-bis(4-hydroxyphenyl)propane, or bisphenol A polycarbonate. The bond geometries calculated with the 6-31G* basis sets are in excellent agreement with the experimental values. The conformational energy contours exhibit a rather low energy barrier (ca. 1.9 kcal/mol) in D P P and a nearly flat profile in DPC for the rotations of phenylene groups. Moreover, the trans conformation of the carbonate group is favored by ca. 2.75 kcal/mol over the cis state.Application of these results to the rotational isomeric state model of the polycarbonate chain leads to the prediction of the unperturbed chain dimension of ( r 2 ) o / M 1.1, which supports the previous calculation of Yoon and Flory. This calculated value is in satisfactory agreement with the experimental results of 1.2-1.3, obtained from small-angle neutron scattering from amorphous polycarbonate by Gawrisch et al. and Ballard et al.

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Section: Unperturbed Chain Dimensionsmentioning

confidence: 99%

Chain conformations of polycarbonate from ab initio calculations

Laskowski¹,

Yoon²,

McLean³

et al. 1988

Macromolecules

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“…The introduction of the entanglement free energy G z not only establishes a quantitative model to explain the entanglement effect in polymer crystallization experiments, but also provides a solution for the discrepancies in polymer crystallization. The difficulty in crystallization of highly entangled polymers like PC, 18,19 the enhanced nucleation in cyclic polymers 54,55 and disentangled systems with reduced entanglement density [56][57][58] can be quantitatively correlated with G z via N e . The discrepancies in the memory effect of crystallization 22,23,[59][60][61][62] and flow-induced crystallization of polymer [63][64][65][66][67][68][69][70] might also be solved with G z , where no theoretical consensus has been reached yet.…”

Section: The Entanglement Free Energy Theorymentioning

confidence: 99%

“…The nucleation of polymer systems with high entanglement density like polycarbonate (PC) is completely suppressed under conventional conditions. 18,19 It is not clear whether this nucleation inhibition mainly stems from the entanglement-enhanced nucleation barrier or constrained chain dynamics. Therefore, the understanding of the role of entanglement in nucleation is critical for developing polymer crystallization theory, which is a longstanding challenge in polymer physics.…”

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confidence: 99%

Entanglement on nucleation barrier of polymer crystal

Fan¹,

Nie²,

Xu³

et al. 2022

Preprint

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We propose a theoretical approach to quantitatively account for the role of entanglement in the nucleation of polymer melts, which is the unique feature of polymer differentiated from small molecules. By performing molecular dynamics simulations, we obtain the nucleation barriers of polymer systems with different entanglement densities, which exhibits an opposite trend compared to the prediction of the classic nucleation theory (CNT). To amend the deficiency of the CNT in polymer crystallization, we introduce the entanglement free energy to reflect the role of entanglement in polymer nucleation. Specifically, the polymer nucleation not only involves free energies of monomers inside and on the surface of a nucleus as considered in the CNT, but also affects the entanglement network around the nucleus. Our theoretical approach provides a reasonable interpretation for the unsolved nucleation phenomena of polymers in simulations and experiments.

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“…Dependent on the moulding conditions, it can be in the crystalline or amorphous state. Only the amorphous polymer has inherently acceptable optical properties [1,2]. Amorphous PCs have been extensively used to replace the conventional engineering materials (i.e.…”

Section: Introductionmentioning

confidence: 99%

Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams

Ehssani¹,

Saghafi²,

Ghoranneviss³

et al. 2010

J. Eur. Opt. Soc.-Rapid Publ.

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In this paper we investigate the effects of visible to near infrared (NIR) laser illumination on the optical transmission (OT) and morphological (MC) alterations of thin, curved surfaces of polycarbonate (PC). The second harmonic of Nd:YAG laser (532 nm) and two diode lasers (665 and 980 nm) were used as illuminating sources. The morphological changes of the PC surfaces are determined using atomic force microscopy (AFM), demonstrating the appreciable changes caused by shorter wavelengths (higher energy). When analyzing the OT spectra of PC thin films, a measurable decrease in the OT of the PC samples which were illuminated by 532, 665 and 980 nm, in particular 532 nm, for energy densities greater than 25 J/cm 2 can be seen.

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Conformational features of bisphenol-A polycarbonate

Cited by 21 publications

References 15 publications

Chain conformations of polycarbonate from ab initio calculations

Chain conformations of polycarbonate from ab initio calculations

Entanglement on nucleation barrier of polymer crystal

Alteration of optical and morphological properties of polycarbonate illuminated by visible/IR laser beams

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