The disordering mechanisms which characterize the pretransitional states of a polymethylene chain inserted in a host material are studied with statistical mechanics. While the intramolecular conformational energy of the chain is chosen according to Floryrsquo;s theory, the interaction with the host material is modeled in terms of a given external potential. The competition between endhyphen;gaucheand kink formation is in particular examined: it is shown that chainhyphen;end distorsions are initially favored and, with increasing temperature, kink formation and longitudinal translation of the molecular chain sustain the disordering process. The results are compared with the experimental data from vibrational spectroscopy.
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