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Rates of conformational transitions in branched chain molecules

A recently developed theory of the kinetics of conformational transitions based on a multi- dimensional extension of Kramers' rate theory is applied to branched polyethylene-like molecules. In particular, the influence of branching on the mechanism and rates of the trans - gauche transition is investigated. As in linear molecules, the reaction coordinate is a localized mode. Thus, the presence of an attached side chain introduces conformational rigidity into one of the tails connected to the transforming rotational angle, and the localized mode behaves akin to related linear molecules. In general, it is found that branches somewhat reduce the transition rate relative to the linear molecule; nevertheless the effect is fairly minor. Therefore, it is concluded that the time scale of conformational transitions in branched and linear chains is the same.