A convenient synthetic route has been developed for preparing the novel rigid 4,5-(PR2)2–2,7,9,9-tetramethylacridane-based pincer ligands (acri-RPNP; R = iPr and Ph), and the first rare-earth (Ln = Y, Lu) alkyl complexes bearing the acri-RPNP ligands were synthesized by a salt metathesis reaction (for the isopropyl-substituent acri-iPrPNP complexes, 1-Ln) or direct alkylation (for the phenyl-substituent acri-PhPNP complexes, 2-Ln). For both 1-Ln and 2-Ln, the NMR spectroscopy and X-ray diffraction study confirmed the successful coordination of the acri-RPNP ligand to the central metal ion in a tridentate manner via the two phosphine and the nitrogen donors. In contrast to 1-Ln that are solvent-free complexes, the metal centers in 2-Ln are each coordinated with one tetrahydrofuran molecule. Upon activation by [Ph3C][B(C6F5)4], 1-Y and 2-Lu could catalyze the living polymerization of isoprene and β-myrcene with high catalytic activity and high cis-1,4-selectivity (up to 92.3% for isoprene and 98.5% for β-myrcene). Moreover, the 1-Y/[Ph3C][B(C6F5)4] catalytic system also could promote the polymerization of butadiene and its copolymerization with isoprene to produce copolymers with high cis-1,4-selectivity and narrow polydispersity.
This work reports the preparation of a hydroxyl terminated polystyrene-b-polybutadiene-b-polystyrene triblock copolymer (SBS) with high cis-1, 4 content via a novel nickel catalyst, [η3-Ni(CH2CHCHCH2OOCH3)][BPhF4]. FT-IR,1H-NMR, and13C NMR indicated that the polybutadiene segment of the copolymer contains greater than 90% cis-1, 4 structure, indicating achievement of the objective. Toward the functionalization goal, a hydroxyl group was successfully introduced at the end of the triblock copolymer (HO–SBS–OH). The results of gel permeation chromatography (GPC) revealed that the polymer is indeed a triblock copolymer, with no traces of homopolymer. Differential scanning calorimetry (DSC) showed that HO–SBS–OH synthesized using the novel catalyst had a lower glass transition temperature (Tg) than HO–SBS–OH synthesized with an alkyl lithium catalyst. Therefore, the polymer synthesized via the novel catalyst contains high cis-1,4 content and displays excellent low-temperature mechanical properties.Keywords:hydroxyl terminated polystyrene-b-polybutadiene-b-polystyrene triblock copolymer;high cis-1,4 content;nickel catalyst
Yufan Yang,Muran He,Yichan Zhang,Chunting Zhou,Chunhuan Luo
The cis-1-chloro-3,3,3-trifluoropropene (R1233zd(Z)) and tetraethylene glycol dimethyl ether (TEGDME) system has been proposed in this study as a potential alternative absorption working pair. The vapor pressure, density, viscosity, and specific heat capacity of the R1233zd(Z)/TEGDME system were measured systematically. The mixing enthalpy and specific enthalpy were calculated by the NRTL model. Regression equations for the measured values were obtained by a least-squares method. Compared with the LiBr/H2O system, the generation temperature of the R1233zd(Z)/TEGDME system is reduced by 12 °C and the viscosity by about 50%. R1233zd(Z)/TEGDME has strong practical application significance in the absorption heat pump system.
危险品化学品经营许可证（带存储）