Towards More Complex Polymethylene Systems

5 Case 5 Moving Towards More Complex Polymethylene Systems 

The role of long alkyl chains in natural phenomena and in industrially relevant systems is well recognized. Due to the flexibility of the polymethylene segments these systems show many phase transitions which are not yet clearly understood at 

We have tried to analyze a few cases with our spectroscopy of defect modes and mention here some of the systems studied. 

The behavior with temperature of C14Zn is totally different [127]. The main phase transition at 100 °C is accompanied by an abrupt generation of conformational defects at 99 °C. Above melting, chains have reached almost a liquidlike structure. Correlations between chains do not exist. However, from the temperature dependence of the factor group splitting of the CH2 bending and 

CH2 rocking modes it is observed that the transition is prepared since the intermolecular forces between chains in C14Zn (weaker than in C14Mn) quickly weaken and the thermal expansion gives more freedom for torsional fluctuations of the alkyl chains, thus leading to conformational collapse. 

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