A transformation process and mechanism between the alpha-conformation and beta-conformation of conjugated polymer PFO in precursor solution

摘要

In this work, the solvent field and temperature are used to explore the mutual transformation dynamic process and mechanism between the alpha-conformation and beta-conformation in poly(9,9-dioctylfluorene) (PFO) precursor solution. The conformational transformation of the PFO chain is researched by UV-vis absorption spectra and the proportions of the beta-conformation are quantitatively calculated. The corresponding variation trend of the aggregation structure is researched using a static and dynamic light scattering (SLS/DLS) method. It is found that the mutual transformation processes between the alpha-conformation and beta-conformation are reversible in essence. Especially in the transformation processes, the complicated relationship between the beta-conformation and the aggregation structure is understood, that is the aggregation structure promotes formation of the beta-conformation under solvent field, then the conformational transformation of the beta-conformation promotes the dissociation of the aggregation structure under temperature. The above results give an insight into the beta-conformation and the aggregation structure of PFO in theory. Furthermore, under the temperature, we find that both two transformation steps have good linear correlations, which indicates that using temperature can be considered as a good method to accurately control the proportion of beta-conformation in actual applications, and it will help us to get the desired proportion of the beta-conformation in PFO precursor solution so as to make the charge carrier mobility of optoelectronic films increased and device performance better.