Influence of Dissolution Status in Eutectic Mixtures on Crystallization Routes of Semiconductive Polyalkylthiophenes

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• 作者：Bei-Kai Yang ; Chi-An Dai ; Chi-Ju Chiang ; Chieh-Nan Lai ; Chao-Cheng Hsu ; Jrjeng Ruan
• 刊名：Crystal Growth & Design
• 出版年：2016
• 出版时间：June 1, 2016
• 年：2016
• 卷：16
• 期：6
• 页码：3143-3153
• 全文大小：769K
• 年卷期：0
• ISSN：1528-7505

文摘

Upon the dissolution of comb-like polyalkylthiophenes in the melt of a crystalline hexamethylbenzene compound, eutectic molten mixtures were prepared, which were found to involve disparate mixing statuses of polyalkylthiophenes. When more than 2 wt % of polyalkylthiophenes is mixed in molten solutions, metastable face-on lamellae of polyalkylthiophenes widely spread upon efficient eutectic solidification, instead of stable edge-on crystalline lamellae. Beyond a critical concentration of polyalkylthiophene, the association of board-like thiophene backbones into stripe-like micelles in molten solutions was proposed as a preceding background. When the association tendency in molten mixture declines with the decrease of concentration or molecular weight, only edge-on lamellae are precipitated. Furthermore, as indicated by the structural analysis via electron diffraction patterns, the stacking of metastable face-on nanostructures is able to transform to stable edge-on crystals via collaborative rotation and lateral association of thiophene backbones. Nevertheless, with the attachment of a longer side chain, this structural evolution is hindered by enhanced kinetic barriers, and thus regular stacking of face-on nanostructures is able to persist and progress as an alternative organization route. For face-on nanostructures serving as a preordering state prior to the growth of edge-on crystals, annealing temperatures capable of initiating an overall structural transition within thin film have been explored and manifested as an indication of the metastability.