Chengdong Yang,Renren Fang,Xiongfa Yang,Ru Chen,Jianhua Gao,Hanghong Fan,Hongxiang Li,Wenping Hu
Graphical Keeping a balance : Novel conjugated copolymers semiconductor materials were synthesized (see figure), and exhibited balanced hole and electron mobility on account of the carbonyl regulation. It is very important to develop ambipolar field effect transistors to construct complementary circuits. To obtain balanced hole- and electron-transport properties, one of the key issues is to regulate the energy levels of the frontier orbitals of the semiconductor materials by structural tailoring, so that they match well with the electrode Fermi levels. Five conjugated copolymers were synthesized and exhibited low LUMO energy levels and narrow bandgaps on account of the strong electron-withdrawing effect of the carbonyl groups. Polymer thin film transistors were prepared by using a solution method and exhibited high and balanced hole and electron mobility of up to 0.46 cm 2 V −1 s −1 , which suggested that these copolymers are promising ambipolar semiconductor materials.
Permeable, selective, and stable polymeric membranes are essential for efficient molecular separation in organic solvents . Polymers of intrinsic microporosity (PIMs) with rigid and twisted chain structures offer abundant pores for high solvent permeability and are emerging as an ideal membrane material. However, guaranteeing high separation selectivity and stability is challenging owing to the wide pore size distribution and low swelling resistance in organic solvents. In this work, we developed intrinsically ultramicroporous polyamides (PAs) with cardo-pendant groups to create crosslinking, ultrathin, and defect-free nanofilms for organic solvent nanofiltration . The molecular simulation confirmed the pivotal role of cardo-pendant group structures in the amine monomers and exhibited their effect in creating pore channel structures within the PAs. Distinctive rigid fluorenyl-based cardo-pendant groups were introduced in amine monomers to finely tailor the packing of PA chains for high ultramicroporosity and a finely tuned pore size. We further achieved the growth of such PAs using a cyclic deposition strategy, in-situ generating highly crosslinking nanofilms with an ultralow thickness of 23–36 nm without structure relaxation. As such, the typically-designed PA membranes demonstrated high and stable solvent permeance (e.g., 18 L m −2 h −1 bar −1 for methanol) and high solute rejection (up to 95 % rejection of 306 Da Azure I), which is superior to its counterparts and current PIM membranes, presenting a new perspective for efficient organic solvent nanofiltration .
Fangxu Fan,Yongchao Sun,Lu Bai,Tianyou Li,Zeyuan Gao,Gaohong He,Canghai Ma
Thermally rearranged (TR) material has emerged as a focal point in gas separation membranes. However, further enhancing the gas separation performance of TR materials remains a key hurdle. In this study, fluorinated-cardo-based diamine (FFDA) was strategically incorporated into the polybenzoxazole structure to improve the gas selectivity. The size-sieving ability of the polymers was significantly enhanced through the interchain hydrogen bonding and π-π stacking induced by the cardo groups. Furthermore, the aromatic fluorine atoms in FFDA exhibited superior CO 2 adsorption capacity. As the thermal rearrangement progressed and the polybenzoxazole structure developed, pores with a diameter of approximately 3 Å were formed, leading to increased diffusion rate of CO 2 and H 2 . The TR400 °C membranes surpassed the 2018 CO 2 /CH 4 mixed-gas upper bound. Particularly, the 6FDA-FFDA/6FAP(1:1)-TR400 membrane achieved a CO 2 permeability of 185.3 Barrer and a CO 2 /CH 4 selectivity of 79.9—representing increases of 227.3 % and 37.5 %, respectively, compared to the precursor membranes. Moreover, the robust structure of the membrane demonstrated enhanced plasticization resistance, with no discernible plasticization observed under CO 2 /CH 4 mixed-gas conditions up to 20 bar. Our design approach paves the way for developing mechanically robust and highly selective TR membranes, with significant potentials for application in CO 2 separation under aggressive conditions.
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