In this study, a highly soluble poly[quinacridone-alt-quinoxaline] series (PQCQx, PQCTQx, PQCTPz) was synthesized through the Suzuki coupling reaction by introducing planar quinacridone and highly soluble quinoxaline. The polymers were soluble in general organic solvents, and the M n was 15.6-85.0 kg mol À1 . The optical band gap energy was 1.82-1.97 eV, which was similar to the band gap of a benzothiadiazole derivative. The HOMO and LUMO levels of the polymers were À5.32 to À5.46 eV and À3.40 to 3.50 eV, respectively. According to XRD measurements, the PQCQx and PQCTPz showed the formation of an ordered lamellar structure and conventional edge-on p-stacking, while the PQCTQx showed face-on formation relative to the substrate. This study also evaluated the OPV characteristics by fabricating a bulk-heterojunction-type polymer solar cell. For the device structure of ITO/PEDOT:PSS/ active layer (PQCTQx:PC 71 BM ¼ 1 : 2 with DIO)/PFN/Al, the values of open-circuit voltage (V OC ), shortcircuit current (J SC ), fill factor (FF) and power conversion efficiency (PCE) were 0.85 V, 7.6 mA cm À2 , 54.9%, and 3.6%, respectively.

In general, the cross-linked epoxy resin is a thermosetting resin, which cannot be dissolved in an organic solvent. Therefore, materials containing epoxy resins, especially carbon-fiber-reinforced plastics (CFRPs), are difficult to recycle. In our study, we succeeded in dissolving the epoxy resin within 2 h at atmospheric pressure and a reaction temperature of 100 °C, which are optimal conditions for the depolymerization; this was achieved by using an aqueous NaOCl solution, which made it possible to recycle these CFRPs. Further, the depolymerization mechanism was determined, which involved the hydroxyl radicals generated from the aqueous NaOCl solution. We identified that an initial pH of 12.05 and a reaction temperature of 100 °C are optimal conditions for the depolymerization of CFRP. Moreover, the reclaimed carbon fibers (CFs) showed physical properties almost similar to those of virgin CFs. In addition, high value-added products were fabricated by using the CFs and resin decomposition products recovered after the decomposition of CFRPs. Thus, the recyclability of CFRPs was maximized to realize minimizing the generation of waste.

Highly soluble poly[quinacridone-alt-benzothiadiazole] (PQCDTB) has been synthesized through the Suzuki coupling reaction by introducing planar quinacridone and highly absorbing benzothiadiazole. The PQCDTB dissolved in general organic solvents, and the M n was 49.8 kg/mol. The optical band gap energy was 1.92 eV, which was similar to the band gap of benzothiadiazole. The HOMO and LUMO levels of PQCDTB were −5.24 eV and −3.32 eV, respectively. According to the XRD measurement, PQCDTB showed the formation of ordered lamellar structure as an out-of-plane peak (h00) by the alkyl side chain of quinacridone and conventional edge-on π- stacking. This study also evaluated the OPV characteristics by fabricating a bulk-heterojunction–type polymer solar cell. When PQCDTB and PC71BM were fabricated in a 1:1 weight ratio, the open-circuit voltage (V OC), short-circuit current (J SC), fill factor (FF), and power conversion efficiency (PCE) were 0.79 V, 5.6 mA cm–2, 55.8% and 2.5%, respectively. In particular, PQCDTB exhibited higher FFs compared with poly[carbazole-alt-benzothiadiazole] (PCZDTB).