物理化学学报 >> 2020, Vol. 36 >> Issue (11): 1908036.doi: 10.3866/PKU.WHXB201908036

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烷基链工程对两亲有机半导体热力学性能影响的研究

李明亮1,2, 李硕1,2, 王国治1,2, 郭雪峰3,4,*()   

  1. 1 有研工程技术研究院有限公司,北京 101407
    2 北京有色金属研究总院智能传感功能材料国家重点实验室,北京 100088
    3 北京大学化学与分子工程学院,北京分子科学国家实验室,分子动态与稳态结构国家重点实验室,北京 100871
    4 北京大学工学院先进材料与纳米技术系,北京 100871
  • 收稿日期:2019-08-29 录用日期:2019-09-12 发布日期:2019-09-17
  • 通讯作者: 郭雪峰 E-mail:guoxf@pku.edu.cn
  • 基金资助:
    中国国家重点研发计划(2017YFA0204901);国家自然科学基金(21727806);北京市自然科学基金(Z181100004418003)

Effects of Alkyl-Chain Engineering on the Thermodynamic Properties of Amphiphilic Organic Semiconductors

Mingliang Li1,2, Shuo Li1,2, Guozhi Wang1,2, Xuefeng Guo3,4,*()   

  1. 1 GRIMAT Engineering Institute Co., Ltd., Beijing 101407, P. R. China
    2 State Key Laboratory of Advanced Materials for Smart Sensing, General Research Institute for Nonferrous Metals, Beijing 100088, P. R. China
    3 State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
    4 Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, P. R. China
  • Received:2019-08-29 Accepted:2019-09-12 Published:2019-09-17
  • Contact: Xuefeng Guo E-mail:guoxf@pku.edu.cn
  • Supported by:
    the National Key R & D Program of China(2017YFA0204901);National Natural Science Foundation of China(21727806);Natural Science Foundation of Beijing, China(Z181100004418003)

摘要:

由于特殊的分子结构,两亲功能分子具有易加工、低成本和高性能等优势,因而广泛应用于功能薄膜材料制备和细胞膜相关的仿生学研究中。于是课题基于侧链工程,设计并合成了一类功能两亲分子CnPA-BTBT (n = 3–11),分子使用不同长度烷基链连接疏水的半导体骨架和亲水的极性功能基团。使用基于示差扫描量热法的热力学研究分析不同长度烷基链的体积效应、奇偶性、柔性和其它烷基链特性对材料整体性能影响,并最终根据热力学测试结果,提出了一个三态分子模型。此工作为功能有机半导体材料设计、合成、优化以及目标性能材料的筛选提供了实验依据。

关键词: 功能两亲半导体材料, 烷基链工程, 热力学, DSC

Abstract:

Due to their special polar structure, amphiphilic molecules are simple to process, low in cost and excellent in material properties. Thus, they can be widely applied in the preparation of functional film materials and bionics related to cell membranes. Therefore, amphiphilic organic semiconductor materials are receiving increasing attention in research and industrial fields. The structure of organic amphiphilic semiconductor molecules usually consists of three functional parts: a hydrophilic group, a hydrophobic group, and a linking group between them. The adjustment of their correlation to achieve the target performance is particularly important and needs experimental discussion regarding synthetic methodologies. In this work, we focused on the engineering of a substituent alkyl-chain, and an amphiphilic functional molecule (benzo[b]benzo[4, 5] thieno[2, 3-d]thiophene, named CnPA-BTBT, n = 3–11) was proposed and synthesized. This molecule links the hydrophobic semiconductor backbone and hydrophilic polar group through alkyl chains of different lengths. Fundamental properties were investigated by nuclear magnetic resonance (NMR) and ultraviolet-visible spectroscopy (UV-Vis) to conform the structure and the band gap properties of the designed organic semiconductor. Thermodynamic features were investigated by thermogravimetric analysis (TGA) and corresponding differential thermal gravity (DTG), which indicate that the functional molecule CnPA-BTBT (n = 3–11) has a great stability in ambient conditions. Moreover, the results show that the binding ability of the amphiphilic molecule to water molecules was regulated by the odd-even alternating effect of the alkyl chain and the intramolecular coupling with BTBT. Furthermore, differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were used to study the material properties in detail. As the length of the alkyl chain increased, the functional molecule CnPA-BTBT (n = 3–11) gradually changed from "hard" species with no thermodynamic changes to a transition one with a pair of thermodynamic peaks, and eventually to a "soft" one as a typical liquid crystal with clear observation of Maltese-cross spherulites. The cooling and freezing points were further studied, and the values and trends of their enthalpy and corresponding temperature fluctuated and alternated due to the volume effect, odd-even alternating effect, flexibility, and other functions of the alkyl chain. Three molecular models were proposed according to the thermodynamic study results, namely the brick-like model, transition model, and liquid crystal model. This work presents in-depth discussion on material structure and corresponding thermodynamic properties, and it is an experimental basis for the design, synthesis, optimization, and screening of target performance materials.

Key words: Functional amphiphilic semiconductor, Alkyl-chain engineering, Thermodynamics, DSC

MSC2000: 

  • O642