Study of the thermal decomposition of pure Pluronic P123 and its role in the calcination of SBA-15 under different conditions

Triblock copolymer P123 is normally used as a template in the SBA-15 synthesis. Calcination is one of the most frequently used processes to remove the template and different references report on the thermal behaviour of this compound during such a process. Nevertheless, there is certain uncertainty regarding this process since, apparently, contradictory results can be found in literature. This paper presents a systematic study of the thermal behaviour of P123, both in its pure state and acting as the SBA-15 template, analysing the influence of the atmosphere (air and nitrogen), amount of sample, heating rate and degree of contact between P123 and SBA, to get a deep insight in the nature of the process. The TGA and DSC techniques have been used to develop a detailed study that allows us to clarify the decomposition and calcination processes of P123. Such a detailed analysis of the P123 decomposition has not been found in previous publications. The interpretation of the results obtained leads to a better understanding of its apparent anomalous behaviour. Under nitrogen, the amount of sample has little effect on the thermal decomposition of pure P123, whereas a strong shift of the process to higher temperatures is detected by increasing the sample amount under air atmosphere. In contrast, in an air atmosphere, this parameter exerts a marked influence due to the thermal acceleration resulting from the cooperative interaction between the behavior of the P123 polymer and a strongly exothermic reaction, which shifts the process toward lower temperatures as the sample mass increases. The effect of the presence of SBA is also evident in the smaller shift of the calcination process up to higher temperatures as the heating rate increases. The results also indicate the different thermal behaviour of P123 depending on the degree of contact with the SBA. The results presented allow a clear interpretation of the nature of the reactions involved.