Fanta Gada Muleta, Jarka Pawel, Szeluga Urszula, Tański Tomasz, Kim Jung Yong
Institute of Engineering Materials and Biomaterials, Faculty of Mechanical Engineering, Silesian University of Technology, 44-100 Gliwice, Poland.
School of Materials Science and Engineering, Jimma Institute of Technology, Jimma University, P.O. Box 378 Jimma, Ethiopia.
Polymers (Basel). 2019 Sep 9;11(9):1474. doi: 10.3390/polym11091474.
Phase diagrams of n-type low bandgap poly{(,'-bis(2-octyldodecyl)naphthalene -1,4,5,8-bis(dicarboximide)-2,6-diyl)-alt-5,5',-(2,2'-bithiophene)} (P(NDI2OD-T2)) solutions and blends were constructed. To this end, we employed the Flory-Huggins (FH) lattice theory for qualitatively understanding the phase behavior of P(NDI2OD-T2) solutions as a function of solvent, chlorobenzene, chloroform, and p-xylene. Herein, the polymer-solvent interaction parameter (χ) was obtained from a water contact angle measurement, leading to the solubility parameter. The phase behavior of these P(NDI2OD-T2) solutions showed both liquid-liquid (L-L) and liquid-solid (L-S) phase transitions. However, depending on the solvent, the relative position of the liquid-liquid phase equilibria (LLE) and solid-liquid phase equilibria (SLE) (i.e., two-phase co-existence curves) could be changed drastically, i.e., LLE > SLE, LLE ≈ SLE, and SLE > LLE. Finally, we studied the phase behavior of the polymer-polymer mixture composed of P(NDI2OD-T2) and regioregular poly(3-hexylthiophene-2,5-dyil) (r-reg P3HT), in which the melting transition curve was compared with the theory of melting point depression combined with the FH model. The FH theory describes excellently the melting temperature of the r-reg P3HT/P(NDI2OD-T2) mixture when the entropic contribution to the polymer-polymer interaction parameter (χ = 116.8 K/ -0.185, dimensionless) was properly accounted for, indicating an increase of entropy by forming a new contact between two different polymer segments. Understanding the phase behavior of the polymer solutions and blends affecting morphologies plays an integral role towards developing polymer optoelectronic devices.
构建了n型低带隙聚{[α,α'-双(2-辛基十二烷基)萘-1,4,5,8-双(二甲酰亚胺)-2,6-二基]-alt-5,5'-(2,2'-联噻吩)}（P(NDI2OD-T2)）溶液和共混物的相图。为此，我们采用弗洛里-哈金斯（FH）晶格理论来定性理解P(NDI2OD-T2)溶液作为溶剂（氯苯、氯仿和对二甲苯）函数的相行为。在此，通过水接触角测量获得聚合物-溶剂相互作用参数（χ），从而得到溶解度参数。这些P(NDI2OD-T2)溶液的相行为显示出液-液（L-L）和液-固（L-S）相变。然而，根据溶剂的不同，液-液相平衡（LLE）和固-液相平衡（SLE）（即两相共存曲线）的相对位置可能会发生显著变化，即LLE > SLE、LLE ≈ SLE和SLE > LLE。最后，我们研究了由P(NDI2OD-T2)和区域规整聚(3-己基噻吩-2,5-二基)（r-reg P3HT）组成的聚合物-聚合物混合物的相行为，其中将熔点转变曲线与结合FH模型的熔点降低理论进行了比较。当对聚合物-聚合物相互作用参数（χ = 116.8 K/ -0.185，无量纲）的熵贡献得到适当考虑时，FH理论出色地描述了r-reg P3HT/P(NDI2OD-T2)混合物的熔融温度，这表明通过在两个不同聚合物链段之间形成新的接触导致熵增加。理解影响形态的聚合物溶液和共混物的相行为对于开发聚合物光电器件起着不可或缺的作用。
