Interactions between a late Ar-O(2) post-discharge and the hexatriacontane (HTC), a long-chain alkane, are shown to depend on the thermal flux released by surface reactions that makes the temperatures of the sample and the gas phase drift in an uncontrolled manner as a function of time. Since the transformations of the hexatriacontane depend on these temperatures, the initial value of the temperature and that of the oxygen concentration are key parameters that control the whole transformation process. A thorough description of the different steps of the transformation undergone by the hexatriacontane is given, explaining the origins of the limitation of the material etching. Pulsing the plasma shows that optimizing the etching process requires to work at low temperature, a too strong heating of the sample leading to functionalization and reticulation that limit the etching of the HTC.