Shufeng Li,Zhe Chen,Yinhua Yang,Zhihao Si,Pei Li,Peiyong Qin,Tianwei Tan
The hydrophobicity of porous particles is important for the performance of mixed-matrix membranes for pervaporation separation of n -butanol aqueous solution. Here, a strategy was proposed to further enhance the hydrophobicity of ZIF-8. ZIF-8 particles were first coated by polydopamine (PDA) to create chemically reactive surface and then modified with silane coupling agents n -propyltrimethoxysilane and n -octyltriethoxysilane. The water contact angles of the obtained P-ZIF-8@PDA and O-ZIF-8@PDA separately increased from 132.8° to 137.3° and 151.5°, which demonstrated a remarkable enhancement in hydrophobicity. The silane-modified ZIF-8 particles were subsequently incorporated into PDMS to fabricate mixed-matrix membranes, which exhibited an improved adsorption selectivity for butanol. The best membrane with 1 wt% loading (O-ZIF-8@PDA) exhibited a separation factor of 56 and butanol flux of 480.6 g m −2 h −1 for a 1.5 wt% butanol solution at 55 °C. The separation factor increased by 23% compared with that of a ZIF-8/PDMS membrane. Moreover, compared with those of a pure PDMS membrane, the separation factor and butanol flux increased by 34% and 85%, respectively. Thus, the strategy is an effective method to improve the PV performance of PDMS membranes for butanol separation.
A new-type of hollow silica@ZIF-8 (HMS@ZIF-8) particle was successfully designed, fabricated and introduced into the fluorinated polybenzoxazole (6FPBO) matrix to prepare the HMS@ZIF-8/6FPBO composite film. Metal–organic frameworks (MOFs) were connected to the surface of hollow silica via covalent bonds, leading to the formation of a shell. Pre-6FPBO prepared from a precursor could be dissolved in organic solvents besides strong corrosive acids, which could protect the filler. HMS@ZIF-8/6FPBO composite films prepared through in situ polymerization and coating exhibited outstanding properties. At both high and room temperatures, the material exhibited excellent dielectric properties. The dielectric constant and dielectric loss decreased down to 2.12 and 0.04, respectively under 1 kHz with the filling of HMS@ZIF-8 particles. HMS@ZIF-8 particles as a filler, evenly dispersed in the matrix, could also improve the tensile modulus of 6FPBO. The tensile modulus of HMS@ZIF-8/6FPBO (6 wt%) increased up to 2.11 GPa, 54% higher than that of the pure 6FPBO matrix. Meanwhile, the composite films demonstrated excellent thermal stability, i.e. the 5% weight loss temperature was higher than 520 °C. This is the first report on MOFs being applied as low dielectric absorbing materials. We believe that the HMS@ZIF-8/6FPBO composite film designed and developed based on this strategy is suitable to be employed in large-scale integrated circuits owing to its excellent dielectric performance, mechanical properties and thermal stability.
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