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Surprising Effects on the Conformational Entropy due to Nonrandom Distributions of Local Conformations Along Unperturbed Chains
Author(s) -
Mattice Wayne L.,
Waheed Numan,
Erguney Fatih
Publication year - 2006
Publication title -
macromolecular theory and simulations
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.37
H-Index - 56
eISSN - 1521-3919
pISSN - 1022-1344
DOI - 10.1002/mats.200600034
Subject(s) - conformational entropy , entropy (arrow of time) , chemistry , tacticity , monomer , helix (gastropod) , configuration entropy , crystallography , thermodynamics , statistical physics , physics , polymer , molecule , ecology , organic chemistry , biology , snail , polymerization
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.