Semiconducting conjugated polymers garnered through the years considerable scientific impact owing to their remarkable electronic properties, stability, and processability[1]. Nevertheless, their functional properties are strongly related to the internal structure, which is of no trivial interpretation, showing in some cases complex configurations such as paracrystallinity or semi-paracrystallinity[2]. Consequently, ensuring certain standards out of these materials necessitates a fundamental comprehension of the structural arrangement of their complex phases, which are also dependent on molecular weight[3].
In this study, we analyse two semiconducting polymers at different molecular weights, PBnDT-FTAZ and D18(Cl), which respectively exhibit lower and higher degrees of order in their chain packing. The main goal of the study is to point out the impact of the chain length on the structure of these polymers, providing valuable information about possible trends for formulation/structure-like predictions. The investigation of the intrinsic configurational order was carried out with the help of GIWAXS (also by in-situ temperature ramp experiments) and AFM techniques, while fast scanning calorimetry allowed the investigation of all those processes involving phase transitions or internal dynamics. The resulting set of results reveals different thermal processes which are directly linked to the inherent structure of the polymers themselves. Furthermore, the in-depth characterization of melting and crystallization phenomena provides insights into how molecular weight influences the kinetics of these phase transitions.
This research contributes to the essential comprehension of semiconducting polymers, offering valuable insights into their complex structures and thermal behaviours, thereby creating opportunities for improved design and application of these materials in present and future technologies.