A potential hyperbranched structure with fluorene-alt-carbazole branches, a three-dimensional-structured SDF core and red Ir(piq)2acac light adjusting units is synthesized for using in highly efficient white polymer light-emitting devices.
A series of hyperbranched polyurethane elastomers (PEO‐HBPUEs) as polymer electrolyte substrate materials was developed for anodic bonding with aluminum (Al) foil in micro‐electro‐mechanical system (MEMS) devices. The PEO‐HBPUEs were prepared by pre‐polymerization method with toluene‐2,4‐diisocyanate(TDI), polypropylene glycol (PPG), 1,4‐butanediol(BDO), trimethylolpropane(TMP), lithium bis(trifluoromethanesulphonyl)imide (LiTFSI), and polyethylene oxide (PEO)‐based electrolyte in varying proportions via solution casting technique at room temperature. All prepared PEO‐HBPUEs exhibited low glass transition temperatures, good thermal stabilities, and suitable mechanical properties. The XRD results showed that PEO‐HBPUEs are amorphous, and LiTFSI was well dissolved in the polymer matrix. The component of PEO‐based electrolyte in PEO‐HBPUEs contributed to increase the ionic conductivity, of which the highest value reached 1.23 × 10−3 S/cm at 75°C for PEO‐HBPUE4. The anodic bonding of PEO‐HBPUE substrate with Al foil was conducted by the coupling action of electric field, temperature field, and pressure field. A clear intermediate bonding layer between the substrate and Al foil was observed and the elements diffusion around bonding layer can be detected by SEM, indicating PEO‐HBPUEs and Al foil have been jointed together successfully. The highest tensile strength of the bonding interface of PEO‐HBPUE4/Al reached 1.88 MPa. All results demonstrated that the prepared PEO‐HBPUEs materials would be promising substrates for flexible MEMS device that can be applied to flexible packaging by anodic bonding technology.
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