Random-coil configurations of poly(vinyl bromide) chains

Sáiz, Enrique; Riande, Enaristo; Delgado, Macarena; Barrales‐Rienda, J. M.

doi:10.1021/ma00232a038

Cited by 13 publications

(7 citation statements)

References 3 publications

(5 reference statements)

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“…From eq 7 and 22, we then find X-1 = 125 A and Mh = 37.3 A"1 in case 1 and X"1 = 48.9 A and ML = 91.3 A"1 in case 2. As seen from Figure 9, for both the RIS model and the HW chain in case 1, Cn exhibits oscillations in the range x 5 30 and then log x…”

Section: Other Polymersmentioning

confidence: 86%

The model parameters of helical wormlike chains

Fujii¹,

Nagasaka²,

Shimada³

et al. 1983

Macromolecules

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1613gether with the values of the parameters EkT/Vo, K and { that characterize networks A and B, respectively (see text), one may evaluate x by solution of eq A-5. Results are given in Table 11.Equation A-10 in conjunction with A-7 may be solved iteratively for u i , given the network parameters, the value of x, and the extension ratio a, relative to the system swollen to equilibrium under isotropic conditions. The reduced force that would obtain if further swelling did not occur as a result of the elongation a, may be calculated according to eq 5 and eq 1-54 of the preceding paper, with VIVO therein equated to l l v , and with AI, and A, determined by a, and VIVO according to eq 1-23. Repetition of the calculation with V'l Vo = 1 / v i , a , ' given by eq A-8, A, given by eq A-7, and All the same as above, yields the calculated reduced stress for the semiopen system at fixed length. The difference between the latter calculation and the former one gives the correction that should be subtracted from the observed reduced stress. Results shown in Figure 3 were corrected in this manner.where A 0 is defined by eq 13 and the principal axes in the order of the diagonal elements are taken parallel to O...O, perpendicular thereto in the plane defined by the Si-0 bonds, and parallel to CHg..CH3, respectively. The anisotropy tensor for the PDMS chain as a whole in any conformation is a linear combination of the group tensors so defined, additivity of these tensors for individual units being assumed. (34) Flory, P. J.; Rehner, J., Jr. , J a p a n . Received J a n u a r y 11, 1983 ABSTRACT T h e model parameters of the helical wormlike chains corresponding to various real polymer chains, both flexible and stiff, are determined from a comparison with the rotational isomeric state models or from an analysis of experimental data for equilibrium and transport properties. Then some general aspects of the behavior of the model parameters are discussed. This serves to guess their probable ranges for a given new polymer. T h e results are useful in a study of the chain dynamics recently initiated on the basis of the discrete helical wormlike chain. 1982, 15, 606.ABSTRACT: Expansion is considered for finite, regular polymethylene stars perturbed by the excluded volume effect. A rotational isomeric state model is used for the chain statistics. The number of bonds in each branch ranges u p to 10 240, and the functionality of the branch point ranges u p to 20. T h e form of the calculation employed here provides a lower bound for the expansion. If the number, n, of bonds in the polymers is held constant, expansion is found to decrease with increasing branch point functionality. Two factors dictate the manner in which finite stars approach the limiting behavior expected for very large stars. These two factors are the chain length dependence a t small n of the characteristic ratio and of (a5 -~? ) / n~/~. In very good solvents these two factors reinforce one another, but they tend to cancel in solvents in which polymer expansion is smal...

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Section: Other Polymersmentioning

confidence: 86%

The model parameters of helical wormlike chains

Fujii¹,

Nagasaka²,

Shimada³

et al. 1983

Macromolecules

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“…iPoly(vinyl carbazole) Abe et al [14] A 066 (2) 2 0.29 0.53, 0.47 0.89 iPoly(methyl vinyl ketone) Suter [15] A 067 2 0.31 0.54, 0.46 0.87 iPoly(N-vinyl pyrrolidone) Tonelli [16] A 063 2 0.33 0.53, 0.47 0.89 iPoly(vinyl bromide) Saiz et al [17] A 012 3 0.43 0.50, 0.46 0.92 Polydimethylsilylene Welsh et al [18] S 087 (FR) 3 0.45 0.44, 0.44 1.00 sPoly(N-vinyl pyrrolidone) Tonelli [16] A 063 2 0.45 0.65, 0.35 0.54 iPolystyrene Yoon et al [19] A 048 2 0.46 0.57, 0.43 0.75 Poly(vinylidene bromide) Carballeira et al [20] S 101 6 0.52 0.27, 0.27 1.00 iPoly(propylene)…”

Section: Polymer Primary Referencementioning

confidence: 99%

Surprising Effects on the Conformational Entropy due to Nonrandom Distributions of Local Conformations Along Unperturbed Chains

Mattice

Waheed

Erguney

2006

Macro Theory & Simulations

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Summary: Nonrandomness in the distribution of rotational isomeric states along a flexible unperturbed chain reduces its conformational entropy. Pairwise interdependence of the bonds is a necessary, but not sufficient, condition for a significant reduction. The reduction in conformational entropy from this source can be as severe as a factor of three. It is generally more severe for isotactic chains than for the syndiotactic chains constructed from the same monomer. Surprising effects are sometimes seen, such as the nearly identical reductions in conformational entropy for polydimethylsiloxane, a very flexible chain, and for poly(methyl methacrylate), a much stiffer chain.Fractional difference in conformational entropy due to nonrandomness versus probability of helix in helix‐coil transition.magnified imageFractional difference in conformational entropy due to nonrandomness versus probability of helix in helix‐coil transition.

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“…The rotational isomeric state model for unperturbed PVB differs from that for PVC in that the C-C-C angles alternate between 112°and 114°, with the larger angle at C-CH2-C, and the statistical weights are r¡ = 1.29, = 0.43, = 0.015, ' = 0.034, and " = 0.0024. 7 The configurational statistics for unperturbed PC1S are adequately described by a rotational isomeric state model developed for unperturbed polystyrene.8 Suitable statistical weights at 300 K are = 1.56, = 0, and = ' = " = 0.045.9 The C-C-C angles alternate between 112°and 114°, as was the case in PVB. We have chosen to place the gauche states at ±120°from the trans state, as was done for PVC and PVB.…”

Section: Simulationsmentioning

confidence: 99%