R Murad Ary, Iraqi Ahmed, Aziz Shujahadeen B, Hi Hunan, N Abdullah Sozan, Brza M A, Abdulwahid Rebar T
Department of Pharmaceutical Chemistry, College of Medical and Applied Sciences, Charmo University, Chamchamal, Sulaimani 46023, Iraq.
Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
Polymers (Basel). 2020 Dec 4;12(12):2910. doi: 10.3390/polym12122910.
In this work four novel donor-acceptor copolymers, PCDTBTDI-DMO, PCDTBTDI-8, P2F-CDTBTDI-DMO and P2F-CDTBTDI-8, were designed and synthesised via Suzuki polymerisation. The first two copolymers consist of 2,7-carbazole flanked by thienyl moieties as the electron donor unit and benzothiadiazole dicarboxylic imide (BTDI) as electron acceptor units. In the structures of P2F-CDTBTDI-DMO and P2F-CDTBTDI-8 copolymers, two fluorine atoms were incorporated at 3,6-positions of 2,7-carbazole to investigate the impact of fluorine upon the optoelectronic, structural and thermal properties of the resulting polymers. P2F-CDTBTDI-8 possesses the highest number average molecular weight ( = 24,200 g mol) among all the polymers synthesised. PCDTBTDI-DMO and PCDTBTDI-8 show identical optical band gaps of 1.76 eV. However, the optical band gaps of fluorinated copolymers are slightly higher than non-fluorinated counterparts. All polymers have deep-lying highest occupied molecular orbital (HOMO) levels. Changing the alkyl chain substituents on BTDI moieties from linear octyl to branched 3,7-dimethyloctyl groups as well as substituting the two hydrogen atoms at 3,6-positions of carbazole unit by fluorine atoms has negligible impact on the HOMO levels of the polymers. Similarly, the lowest unoccupied molecular orbital (LUMO) energy levels are almost comparable for all polymers. Thermogravimetric analysis (TGA) has shown that all polymers have good thermal stability and also confirmed that the fluorinated copolymers have higher thermal stability relative to those non-fluorinated analogues. Powder X-ray diffraction (XRD) studies proved that all polymers have an amorphous nature in the solid state.
在本研究中，通过铃木聚合反应设计并合成了四种新型供体-受体共聚物，即PCDTBTDI-DMO、PCDTBTDI-8、P2F-CDTBTDI-DMO和P2F-CDTBTDI-8。前两种共聚物由噻吩基作为电子供体单元、苯并噻二唑二羧酸亚胺（BTDI）作为电子受体单元连接在2,7-咔唑两侧构成。在P2F-CDTBTDI-DMO和P2F-CDTBTDI-8共聚物结构中，在2,7-咔唑的3,6位引入了两个氟原子，以研究氟对所得聚合物的光电、结构和热性能的影响。P2F-CDTBTDI-8在所有合成聚合物中具有最高的数均分子量（ = 24,200 g/mol）。PCDTBTDI-DMO和PCDTBTDI-8显示出相同的1.76 eV光学带隙。然而，氟化共聚物的光学带隙略高于未氟化的对应物。所有聚合物都具有较深的最高占据分子轨道（HOMO）能级。将BTDI部分的烷基链取代基从直链辛基变为支链3,7-二甲基辛基，以及用氟原子取代咔唑单元3,6位的两个氢原子，对聚合物的HOMO能级影响可忽略不计。同样，所有聚合物的最低未占据分子轨道（LUMO）能级几乎相当。热重分析（TGA）表明所有聚合物都具有良好的热稳定性，并且还证实氟化共聚物相对于那些未氟化的类似物具有更高的热稳定性。粉末X射线衍射（XRD）研究证明所有聚合物在固态下均为无定形性质。
