Solution properties and chain dimensions of poly(trimethylene sulfide)

Sánchez, Ángeles Díaz; Bello, A.; Marco, Carlos; Fatou, J. G.

doi:10.1002/macp.1988.021890213

Cited by 12 publications

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“…The optimized energy parameters are listed in columns of “exptl” of Table . c Estimated from intrinsic viscosities of PTMS in a good solvent, CHCl 3 .…”

Section: Resultsmentioning

confidence: 99%

Conformational Characteristics of Poly(trimethylene sulfide) and Structure−Property Relationships of Representative Polysulfides and Polyethers

Sasanuma

Watanabe

2006

Macromolecules

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Conformational characteristics of poly(trimethylene sulfide) (PTMS) have been investigated by a rotational isomeric state analysis of ab initio molecular orbital calculations and 1 H and 13 C NMR experiments for a monomeric model compound, 1,3-bis(methylthio)propane, and the characteristic ratio and dipole moment ratio of the unperturbed PTMS chain. Both C-S (the first-order interaction energy, -0.30 kcal mol -1 ) and C-C (-0.58 kcal mol -1 ) bonds prefer the gauche conformation. For comparison, conformational analysis of the corresponding polyether, poly(trimethylene oxide), has also been carried out. The C-O (+0.97 kcal mol -1 ) and C-C (-0.47 kcal mol -1 ) bonds show trans and gauche preferences, respectively. These results are consistent with the conformational stabilities predicted by the natural bond orbital analysis on model compounds of poly-(ethylene sulfide) (PES) and poly(ethylene oxide). Without the strong S‚‚‚S repulsion, therefore, the C-C bond adjacent to the C-S bond exhibits its inherent gauche preference. Without the (C-H)‚‚‚O attraction, the ethereal C-C bond is subject to the attractive gauche effect. For representative polysulfides and polyethers, relationships between conformations in the Θ and crystalline states and thermal properties have been investigated. Even in the Θ and crystalline states, the polymers mostly keep the conformational preferences found for their small model compounds; as an exception, poly(propylene sulfide) and poly(propylene oxide), having a methyl side chain, crystallize to adopt the metastable all-trans conformation. On average, the configurational entropy of the polymers amounts to 80-90% of entropy of fusion, and the configurational energy change between crystalline and molten states accounts for ca. 30% of enthalpy of fusion. Of the polymers investigated here, PES has an exceptionally high melting point; the dipole-dipole interaction in the PES crystal was evaluated to be -1.0 kcal mol -1 (ca. 30% of the enthalpy of fusion), thus being the source of the thermostability.

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“…The optimized energy parameters are listed in columns of “exptl” of Table . c Estimated from intrinsic viscosities of PTMS in a good solvent, CHCl 3 .…”

Section: Resultsmentioning

confidence: 99%