基于一种新型含菲并咪唑基二胺单体的聚酰亚胺的合成与性能

通过三步反应合成了一种新型具有高度扭曲构型的芳香二胺单体1,2-双(4-(4-氨基-2-三氟甲基苯氧基)苯基)-菲并[9,10-d]咪唑(PIPOTFA),将它与四种商业化二酐4,4'-六氟异丙基邻苯二甲酸酐(6FDA)、3,3',4,4'-二苯醚四甲酸二酐(ODPA)、3,3',4,4'-联苯四甲酸二酐(BPDA)和3,3',4,4'-二苯甲酮四甲酸二酐(BTDA)通过高温一步法聚合制得了四种聚酰亚胺均聚物。这些聚酰亚胺在N-甲基吡咯烷酮(NMP)、N,N-二甲基乙酰胺(DMAc)和N,N-二甲基甲酰胺(DMF)等非质子极性溶剂中均具有良好的溶解性。热分析测试结果表明,这些聚酰亚胺具有优异的热稳定性,其玻璃化转变温度在265~290℃之间,氮气气氛下5%和10%热失重温度分别为517~561℃和547~587℃,700℃时的残炭率为60%~70%。这些聚酰亚胺薄膜呈淡黄色,在450nm处的透过率为11%~68%,截止波长为375~383nm。

通过添加离子键聚合物和应用动态硫化控制PP/EPDM共混胶的混溶性

橡胶在切变状态下的硫化称为'动态硫化'。由于在加工方面的优点,动态下硫化的热塑性共混弹性体已广泛地应用于塑料工业;既使在交联弹性体的存在下采用动态硫化也可获得热塑性。

Polyethyleneimine-integrated composite sorbents for emerging pollutants remediation in water: Cross-linking strategy and tailored affinity

The removal and enrichment of pollutants in industrial wastewater using efficient adsorption processes have been a hot scientific topic in the field of environmental chemistry and green chemistry.Compared with the progress in the design,synthesis,and performance of polyethyleneimine-modified adsorbent materials at home and abroad,there are few reviews on how to modify polyethyleneimine(PEI)in adsorbent materials through functional group reactions.Therefore,this review attempts to provide a systematic review of how PEI can prepare adsorbent materials by functional group reaction and the adsorption mechanism of inorganic metal ions,phosphates,and dyes in wastewater by PEI.On this basis,future research directions of adsorbent materials are prepared by PEI prospects.

Facile Synthesis of Porous Carbon Nitride Spheres with Hierarchical Three-Dimensional Mesostructures for CO_(2) Capture

Porous carbon nitride(CN)spheres with partially crystalline frameworks have been successfully synthesized via a nanocasting approach by using spherical mesoporous cellular silica foams(MCFs)as a hard template,and ethylenediamine and carbon tetrachloride as precursors.The resulting spherical CN materials have uniform diameters of ca.4μm,hierarchical three-dimensional(3-D)mesostructures with small and large mesopores with pore diameters centered at ca.4.0 and 43 nm,respectively,a relatively high BET surface area of~550 m^(2)/g,and a pore volume of 0.90 cm^(3)/g.High-resolution transmission electron microscope(HRTEM)images,wide-angle X-ray diffraction(XRD)patterns,and Raman spectra demonstrate that the porous CN material has a partly graphitized structure.In addition,elemental analyses,X-ray photoelectron spectra(XPS),Fourier transform infrared spectra(FT-IR),and CO_(2) temperature-programmed desorption(CO_(2)-TPD)show that the material has a high nitrogen content(17.8 wt%)with nitrogen-containing groups and abundant basic sites.The hierarchical porous CN spheres have excellent CO_(2) capture properties with a capacity of 2.90 mmol/g at 25℃and 0.97 mmol/g at 75℃,superior to those of the pure carbon materials with analogous mesostructures.This can be mainly attributed to the abundant nitrogen-containing basic groups,hierarchical mesostructure,relatively high BET surface area and stable framework.Furthermore,the presence of a large number of micropores and small mesopores also enhance the CO_(2) capture performance,owing to the capillary condensation effect.

“One stone,two birds”solvent system to fabricate microcrystalline cellulose–Ti_(3)C_(2)T_(x)nanocomposite film as a flexible dielectric and thermally conductive material

A strategy for fabricating microcrystalline cellulose–Ti_(3)C_(2)T_(x)(MCC–MXene)nanocomposite films with high relative permittivity,high thermal conductivity,and excellent mechanical properties was developed.The MCC–MXene nanocomposite film was fabricated by casting a solution containing N,N-dimethylacetamide/lithium chloride(DMAc/LiCl)-soluble MCC and DMAcdispersible MXene nanosheets,followed by humidity control drying.The MXene nanosheets greatly enhanced the permittivity of the nanocomposite films owing to interfacial polarization.Thus,the nanocomposite film with 20 wt.%MXene content achieved a desirable permittivity of 71.4 at 102 Hz(a 770%improvement against that of neat cellulose),while the dielectric loss only increased by 1.8 times(from 0.39 to 0.70).The obtained nanocomposite films with 20 wt.%and 30 wt.%MXene exhibited remarkable in-plane thermal conductivities of 8.523 and 9.668 W∙m^(−1)∙K^(−1),respectively,owing to the uniform dispersion and selfalignment of the MXene layered structure.Additionally,the uniformly dispersed MXene nanosheets in the MCC network with interfacial interaction(hydrogen bonding)and mechanical entanglement endowed the nanocomposite films with excellent mechanical properties and flexibility.Furthermore,the thermal stability,water resistance,and antibacterial properties of the nanocomposite films were effectively improved with the introduction of MXene.Moreover,using DMAc/LiCl as the solvent system not only improves the compatibility between MCC and MXene but also avoids the problem of easy oxidation of MXene in aqueous systems.With the high stability of the MCC–MXene solution and enhanced properties of the MCC–MXene films,the proposed strategy manifests great potential for fabricating natural biomass-based dielectric materials.