Yiran Wang,Xianhong Zhang,Yuhong Ma,Dong Chen,Changwen Zhao,Wantai Yang
This study reports a step-growth click-polymerization of 1,4-benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE) with 4-( N,N -diphenylamino)-benzaldehyde (DPAB) as a photoredox catalyst under irradiation of visible light. DPAB exhibits a strong UV–vis absorption at 350 nm and a strong fluorescence emission at 480 nm in anisole. There is a strong fluorescence quenching between BDMT and DPAB. The molecular weight of the polythiolether can be controlled by reaction time and monomer feed ratios. More importantly, α,ω-dithiol and α,ω-divinyl telechelic polythiolether oligomers are successfully synthesized by simply changing the molar ratios of BDMT to DEGVE. 1 H NMR and MALDI-TOF MS spectra demonstrate that the oligomers have high end group fidelity. In addition, strong fluorescence is observed when the α,ω-dithiol terminated polythiolether adds with N -(1-pyrenyl) maleimide, indicating that the as-prepared polythiolether bears reactive thiol end groups. Furthermore, high molecular weight polythiolether are prepared by chain extension with reactive polythiolether oligomers as macro-monomers. For example, α,ω-divinyl oligomer ( M n = 2000 g mol −1 ) could further react with α,ω-dithiol oligomer ( M n = 2400 g mol −1 ) to form high molecular weight polythiolether ( M n = 6000 g mol −1 ).
Six aryl Pd(II) bromide complexes based on perylene diimide derivative (Ar) and phosphine mixed-ligands are successfully synthesized by directly oxidative addition of Ar–Br to the Pd(0) precursor. These complexes with the general formulas ArPdBr(PCy 3 ) 2 (PCy 3 = tricyclohexylphosphine; Pd1–Pd3 ) and [ArPdBr(TXP-2,4)] 2 (TXP-2,4 = tri-2,4-xylylphosphine; Pd4–Pd6 ) are stable and can be handled in air at room temperature. By employing the Pd(II) complexes as initiators, Suzuki catalyst transfer polymerization (SCTP) of AB-type fluorene monomer is investigated for preparing polyfluorenes (PFs) with the defined end group. Complexes Pd4–Pd6 with auxiliary TXP-2,4 ligand can initiate polymerization of AB-type fluorene monomer at room temperature, while higher polymerization temperature is required for Pd1–Pd3 with alkyl phosphine PCy 3 . The obtained polymers are analyzed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry, which confirms that the Ar group is appended to the terminus of the polymer chain. Moreover, PFs prepared by Pd4–Pd6 -catalyzed SCTP bear precisely the Ar group on one chain end and 4- tert -butylphenyl end-capping group on the opposite end, which indicates that Pd4–Pd6 with the bulky TXP-2,4 exhibit better catalytic performance in SCTP. Photoluminescence spectra of the obtained polymers show a dual or a blue emission resulting from the difference of the molecular weight.
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