Liangliang Dong

Improving CO2/N2 separation performance using nonionic surfactant Tween containing polymeric gel membranes

Polymeric gel membranes containing 0 to 65 wt% of Tween20, Tween21 and Tween80 in PEBA2533 were prepared using a solvent casting method. The effect of Tween with different lengths of alkyl chain on the properties and performance of the gel membranes was discussed. The results showed a better compatibility of PEBA2533 with Tween21 than Tween20 and Tween80. Both the pure CO2 permeability and CO2/N2 selectivity increased with the increase in the number of N-alkyl groups in Tween. On the other hand, with the increase of Tween content, CO2 permeability and CO2/N2 selectivity simultaneously increased. The best separation performance was achieved for the PEBA2533/Tween80-65 gel membrane, which had CO2 permeability of 289 Barrer and CO2/N2 selectivity of 40.70, at 0.6 atm and 25 °C. This suggests a potential application in gas separation membranes, for instance for CO2 capture.

ZIF-8 Filled Polydimethylsiloxane Membranes for Pervaporative Separation of n-Butanol from Aqueous Solution

ZIF-8-filled polydimethylsiloxane (PDMS) membranes, PDMS/ZIF-8, were prepared by a two-step polymerization process and were used to recover n-butanol from an aqueous solution by pervaporation (PV). Compared with pure PDMS membrane, PDMS/ZIF-8 membranes demonstrated an obviously higher n-butanol permselectivity. As an increase of ZIF-8 content, n-butanol/water selectivity increased initially and then decreased, while the n-butanol and water permeability decreased monotonously. PDMS/ZIF-8 membrane containing 2 wt% ZIF-8, that is, PDMS/ZIF-8-2 showed the highest selectivity. On the other hand, selectivity and permeability for n-butanol and water of PDMS/ZIF-8-2 membrane decreased with the increase of operating temperature. The selectivity and permeability for n-butanol reached 7.1 and 3.28 × 105 barrer, respectively, at 30°C when the feed concentration of n-butanol was 0.96 wt%.

High performance polydimethylsiloxane pervaporative membranes with hyperbranched polysiloxane as a crosslinker for separation of n-butanol from water

Hyperbranched polysiloxane (HPSiO) was successfully synthesized by a three-step process. The result of 29Si Nuclear Magnetic Resonance (NMR) measurement indicates that the degree of branching (DB) of HPSiO is 0.73. Then, novel polysiloxane membranes, HPSiO-c-PDMS, were prepared by the cross-linking reaction between HPSiO and α,ω-dihydroxypolydimethylsiloxane (H-PDMS) with different molecular weights. HPSiO-c-PDMS membranes were first used as membrane materials for recovering n-butanol from an aqueous solution by pervaporation (PV). The HPSiO-c-PDMS membranes demonstrated high n-butanol/water selectivity as well as high permeability. As the molecular weight of H-PDMS increased, the selectivity increased and the n-butanol permeability of HPSiO-c-PDMS-2 (with moderate H-PDMS molecular weight) membrane showed the highest value. The effects of temperature and feed concentration on the PV performances were also investigated. The PV performance, n-butanol permeability and n-butanol/water selectivity of the HPSiO-c-PDMS-2 membrane, reached 4.3 × 105 Barrer and 8.75, respectively, with a feed concentration of 1.0 wt% at 30 °C.

Multi-functional polydopamine coating: simultaneous enhancement of interfacial adhesion and CO2 separation performance of mixed matrix membranes

Inspired by marine mussels adhesive system and facilitated transport membranes, we proposed a novel strategy to simultaneously improve the MOF–polymer interface and CO2 separation performance by coating polydopamine (PDA) on the surface of ZIF-8. PDA@ZIF-8 played multiple roles in enhancing the membrane performance. First, the inherent high permeability of ZIF-8 with ultra-microporosity was anticipated to optimize the fractional free volume and enhance the gas permeability of MMMs. Second, the PDA coating can mitigate the interfacial defects and improve the adhesion between ZIF-8 and the polymer matrix. Finally, the abundant –OH and amino groups in PDA have strong interaction with CO2 molecules, which can effectively facilitate CO2 transport. The membrane separation performance for pure gases (CO2 and N2) of the PDA@ZIF-8 incorporated Pebax membrane was investigated and compared with that of the ZIF-8-incorporated membrane without the PDA coating. An anti-tradeoff effect was obtained by addition of PDA@ZIF-8. In particular, the Pebax/PDA@ZIF-8-15 MMM showed the best gas separation performance with a CO2 permeability of 267.74 Barrer and a CO2/N2 selectivity of 62.65, surpassing Robesons upper bound from 2008.

Efficient CO2 capture by metallo-supramolecular polymers as fillers to fabricate a polymeric blend membrane

Novel fillers based on metallo-supramolecular polymers were incorporated into PEBA2533 to obtain gas separation membranes, which exhibit excellent CO2 permeability and CO2/N2 selectivity.

Enhanced CO2 separation performance of P(PEGMA-co-DEAEMA-co-MMA) copolymer membrane through the synergistic effect of EO groups and amino groups

We report a high performance and CO2-philic, comb copolymer consisting of poly(ethylene glycol) methyl ether methacrylate (PEGMA), polymethyl methacrylate (PMMA) and poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) for use in composite membranes for CO2/N2 separation. Since the copolymers contain ethylene oxide (EO) groups and amino groups, the separation performance was expected to be enhanced by the synergistic effect of (1) the increased solubility of CO2 by dipole–dipole interactions between CO2 and EO units and (2) the enhanced CO2 transport by reversible reactions between CO2 and amino groups. The best separation performance was obtained from the PEDM5 composite membrane with 25 mol% of PEGMA, at which the CO2 permeability was 308 barrer and CO2/N2 selectivity was 38, which displays a potentially promising alternative for CO2 separation from N2.

Preparation of jujube-cake structure membranes through in situ polymerization of hyperbranched polysiloxane in ethylene-vinyl acetate matrix for separation of ethyl acetate from water

Ethylene-vinyl acetate (EVA)/hyperbranched polysiloxane (HPSiO) hybrid pervaporative membranes for separation of ethyl acetate (EA) from water with a “jujube-cake” structure were prepared by in situ polymerization. The morphology of the EVA/HPSiO membranes was characterized by using a scanning electron microscope (SEM) and transmission electron micrographs (TEM). The mechanical properties, contact angle, density, void volume and swelling behavior of the membranes were investigated. We also studied the effect of HPSiO content, operating temperature and feed concentration on the separation properties of EA/water mixtures. The results show that the addition of appropriate HPSiO could improve the hydrophobicity of the membranes, which is helpful to recover EA from water. The membrane, loading 20 wt% HPSiO, exhibited the highest separation factor and permeability for a feed concentration of 1 wt% at 30 °C.

Poly(ether-b-amide)/Tween20 Gel Membranes for CO2/N2 Separation

Poly(ether-b-amide) (PEBA)/Tween20 gel membranes containing from 0 wt% to 65 wt% of Tween20 in PEBA2533, PEBA3533, and PEBA4033 were prepared by solvent casting method for CO2/N2 separation. The gas separation properties of the polymeric gel membranes were tested for single gases of CO2 and N2 at 25°C with the feed pressure of 0.6 atm. For all pure PEBA membranes, CO2 and N2 permeability decreased as the amount of polyamide block increased, but CO2/N2 selectivity increased. For PEBA/Tween20 gel membranes, both the CO2 permeability and CO2/N2 selectivity were greatly enhanced with the increase of Tween20 content. For the membrane of PEBA4033/Tween20-65, CO2/N2 selectivity, and CO2 permeability reached 54 and 146 Barrer, respectively, which is very interesting for potential application in CO2 removal from flue gas.

Tuning the size and morphology of zeolitic imidazolate framework-8 in a membrane dispersion reactor

Zeolitic imidazolate framework-8 (ZIF-8) with different sizes and morphologies were successfully synthesized using a membrane dispersion reactor (MDR). The MDR synthesis applied in this paper was expected to be an efficient and economical way to synthesize ZIF materials.

Controllable Synthesis of Multiarm Star-Shaped Copolymers Composed of Phosphoester Chains and Their Application on Drug Delivery

Novel biodegradable polymers with specific properties, structures, and tailorable designs or modifications are in great demand. Poly(phosphoester)s with good biocompatibility and degradability, as well as other adjustable properties have been studied widely because of their potential in biomedical applications. To meet more versatile and diverse biomedical applications, a novel multiarm star-shaped phosphorester triblock copolymer poly(amido amine)-block-poly(2-butynyl phospholane)-block-poly(2-methoxy phospholane) (PAMAM-PBYP-PMP) is synthesized via organo-catalyzed sequential ring-opening polymerization. Supramolecular micelles with good architectural stability are self-assembled into uniform spherical morphology in aqueous solution. Doxorubicin (DOX) can be encapsulated into the micelles with efficient loading capacity. A slow and sustained release in the environment of simulated intracellular lysosome (pH 5.0 with phosphodiesterase I) is observed. In addition, the copolymers and DOX-loaded supramolecular micelles exhibit low cell-toxicity and excellent anticancer activity toward HeLa cells. As a consequence, this multiarm star-shaped PAMAM-PBYP-PMP has great potential in drug delivery system for tumor treatment.