scholarly journals Electropolymerization of robust conjugated microporous polymer membranes for rapid solvent transport and narrow molecular sieving

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zongyao Zhou ◽  
Xiang Li ◽  
Dong Guo ◽  
Digambar B. Shinde ◽  
Dongwei Lu ◽  
...  
Keyword(s):  
Pore Size ◽  
Spider Silk ◽  
Polymer Membranes ◽  
Polymer Materials ◽  
Critical Parameters ◽  
Separation Performance ◽  
High Porosity ◽  
Molecular Sieving ◽  
Uniform Pore Size ◽  
Solvent Transport

Abstract Pore size uniformity is one of the most critical parameters in determining membrane separation performance. Recently, a novel type of conjugated microporous polymers (CMPs) has shown uniform pore size and high porosity. However, their brittle nature has prevented them from preparing robust membranes. Inspired by the skin-core architecture of spider silk that offers both high strength and high ductility, herein we report an electropolymerization process to prepare a CMP membrane from a rigid carbazole monomer, 2,2’,7,7’-tetra(carbazol-9-yl)-9,9’-spirobifluorene, inside a robust carbon nanotube scaffold. The obtained membranes showed superior mechanical strength and ductility, high surface area, and uniform pore size of approximately 1 nm. The superfast solvent transport and excellent molecular sieving well surpass the performance of most reported polymer membranes. Our method makes it possible to use rigid CMPs membranes in pressure-driven membrane processes, providing potential applications for this important category of polymer materials.

Preparation of Porous Polymer Membrane with Controllable Pore Size via Spray Spinning

2017 ◽  
Vol 909 ◽  
pp. 157-162
Author(s):  
Wen Ting Sun ◽  
Shuang Xi Liu ◽  
Xiao Yu Hu ◽  
Qiu Ying Jia ◽  
Ya Qin Shen ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Polymer Membranes ◽  
Processing Parameters ◽  
Polymer Membrane ◽  
Water Soluble ◽  
Porous Polymer ◽  
The Novel ◽  
Uniform Pore Size

Polymer membranes with fixed pore size or narrow pore size distribution can be used for special separation. However, polymer membranes prepared by conventional method usually have wide pore size distribution and the pore size is hard to control. Here we prepared a porous polymer membrane with uniform pore size via spraying a blend of polystyrene (PS) and polyethylene oxide (PEO) on a filtration paper. Dissolving the water-soluble component (PEO) forms the pore and varying the ratios of PEO in the blend controls the pore size. The pore size and size distribution are also affected by processing parameters, such as the flow rate of solution and carrier gas, and gap length. The morphologies of the membrane are observed using scanning electron microscopy (SEM). The novel polymer membrane with controllable and uniform pore size will be used for the separation of solutes with predictable sizes.

scholarly journals Highly Mesoporous g-C3N4 with Uniform Pore Size Distribution via the Template-Free Method to Enhanced Solar-Driven Tetracycline Degradation

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2041
Author(s):  
Bao Lee Phoon ◽  
Chin Wei Lai ◽  
Guan-Ting Pan ◽  
Thomas C.-K. Yang ◽  
Joon Ching Juan
Keyword(s):  
Visible Light ◽  
Pore Size ◽  
Separation Efficiency ◽  
Light Irradiation ◽  
High Porosity ◽  
Solar Light Irradiation ◽  
Tetracycline Degradation ◽  
Template Free ◽  
Carrier Separation ◽  
Uniform Pore Size

A highly mesoporous graphitic carbon nitride g-C3N4 (GCN) has been produced by a template-free method and effectively photodegrade tetracycline (TC) antibiotic under solar light irradiation. The mesoporous GCN (GCN-500) greatly improves the photoactivity (0.0247 min−1) by 2.13 times, as compared to that of bulk GCN (0.0116 min−1). The efficiently strengthened photoactivity is ascribed to the high porosity (117.05 m2/g), and improves the optical absorption under visible light (Eg = 2.65 eV) and good charge carrier separation efficiency. The synthesized mesoporous GCN shows a uniform pore size (~3 nm) distribution. GCN-500 shows large pore volume (0.210 cm3/g) compared to GCN-B (0.083 cm3/g). Besides, the GCN-500 also exhibits good recyclability and photostability for TC photodegradation. In conclusion, GCN-500 is a recyclable photocatalyst for the removal of TC under visible light irradiation.

scholarly journals The spirobichroman-based polyimides with different side groups: from structure–property relationships to chain packing and gas transport performance

RSC Advances ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 5086-5095
Author(s):  
Shuli Wang ◽  
Xiaohua Tong ◽  
Chunbo Wang ◽  
Xiaocui Han ◽  
Sizhuo Jin ◽  
...  
Keyword(s):  
Dihedral Angle ◽  
Gas Separation ◽  
Gas Transport ◽  
Critical Role ◽  
Polymer Membranes ◽  
Separation Performance ◽  
Structure Property ◽  
Chain Packing ◽  
Structure Property Relationships ◽  
Gas Separation Performance

Effect of substituents on the dihedral angle and chain packing plays a critical role in the enhancement in the gas separation performance of polymer membranes.

scholarly journals Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 523-540
Author(s):  
Imed Beghoura ◽  
Joao Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Size ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
Porous Structures ◽  
Foaming Agent ◽  
Al Powder ◽  
Highly Porous ◽  
Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

Dehydrogenation of Propane to Propene over Mesoporous ZrO2-Supported VCrO Catalysts

2014 ◽  
Vol 1008-1009 ◽  
pp. 290-294
Author(s):  
Bao Agula ◽  
Si Qin Dalai ◽  
Yue Chao Wu
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mesoporous Structure ◽  
Molar Ratio ◽  
Impregnation Method ◽  
Size Distributions ◽  
Tem Analysis ◽  
Surfactant Assisted ◽  
Uniform Pore Size

Mesoporous ZrO2with narrow mesopore size distributions has been prepared by the surfactant-assisted method of nanoparticle assembly. A series of VCrO/ZrO2catalysts with different V/Cr molar ratio (0.3, 0.6, 1.0, 1.3 and 1.6) were prepared by the wetness impregnation method and characterized by XRD, N2adsorption and TEM techniques. N2adsorption and TEM analysis revealed that the surfactant-assisted method prepared VCrO/ZrO2catalysts have wormhole-like mesoporous structure with uniform pore size distribution. VCrO/ZrO2catalysts have been applied for direct dehydrogenation of propane to propene. The optimistic catalyst was V/Cr-0.6 with highest yield of 41.7% the corresponding conversion of propane was 44.1% and selectivity to propene was 94.5% at 550 °C.

Preparation of Nano-Fibrous Poly(L-lactic acid) Scaffold with Hierarchical Pores

2011 ◽  
Vol 418-420 ◽  
pp. 303-306
Author(s):  
Xue Jun Wang ◽  
Tao Lou ◽  
Guo Jun Song
Keyword(s):  
Tissue Engineering ◽  
Lactic Acid ◽  
Pore Size ◽  
Composite Scaffold ◽  
Compressive Modulus ◽  
High Porosity ◽  
Nano Composite ◽  
Hierarchical Pores ◽  
Fiber Size ◽  
Hierarchical Pore

In this study, a nano-fibrous PLLA scaffold with hierarchical pore was sucessfully fabricated using combined TIPS and particle leaching method.The scaffold had a nano-fibrous PLLA matrix (fiber size 100-800 nm), an interconnective hierarchical pores (1.0- 425 μm), high porosity (>96%). The compressive modulus of scaffold with different pore size was between 0.16 MPa to 0.2 Mpa and it decreased with the increased salt size embedded in. The new nano composite scaffold is potentially a very promising scaffold for tissue engineering.

scholarly journals PEG/PPG-PDMS-Adamantane-Based Crosslinked Terpolymer Using the ROMP Technique to Prepare a Highly Permeable and CO2-Selective Polymer Membrane

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1674
Author(s):  
Dongyoung Kim ◽  
Iqubal Hossain ◽  
Yeonho Kim ◽  
Ook Choi ◽  
Tae-Hyun Kim
Keyword(s):  
Ring Opening ◽  
Polymer Membranes ◽  
Crosslinking Density ◽  
Polymerization Process ◽  
Separation Performance ◽  
High Permeability ◽  
High Solubility ◽  
Crosslinked Polymer ◽  
Precursor Molecules ◽  
Gas Separation Performance

In this study, precursor molecules based on PEG/PPG and polydimethylsiloxane (PDMS), both widely used rubbery polymers, were copolymerized with bulky adamantane into copolymer membranes. Ring-opening metathesis polymerization (ROMP) was employed during the polymerization process to create a structure with both ends crosslinked. The precursor molecules and corresponding polymer membranes were characterized using various analytical methods. The polymer membranes were fabricated using different compositions of PDMS and adamantane, to determine how the network structure affected their gas separation performance. PEG/PPG, in which CO2 is highly soluble, was copolymerized with PDMS, which has high permeability, and adamantane, which controlled the crosslinking density with a rigid and bulky structure. It was confirmed that the resulting crosslinked polymer membranes exhibited high solubility and diffusivity for CO2. Further, their crosslinked structure using ROMP technique made it possible to form good films. The membranes fabricated in the present study exhibited excellent performance, i.e., CO2 permeability of up to 514.5 Barrer and CO2/N2 selectivity of 50.9.

scholarly journals Minimizing Drying Shrinkage and Enhancing Impermeability of Foam Concrete Modified with Epoxy Resin

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Jianqing Gong ◽  
Ke Li
Keyword(s):  
Surface Energy ◽  
Pore Size ◽  
Epoxy Resin ◽  
Average Pore Size ◽  
Drying Shrinkage ◽  
Maximum Level ◽  
High Porosity ◽  
Foam Concrete ◽  
Average Pore ◽  
Internal Pore Structure

Relatively high drying shrinkage and permeability were two of the major challenges associated with foam concrete (FC), primarily due to its high porosity nature. This study was aimed at reducing the drying shrinkage and improving the impermeability of FC by blending and modifying it with epoxy resin (EP). Extensive laboratory testing yielded an optimum content of 4.0% EP, corresponding to a minimum drying shrinkage rate of 1.47 mm/m, which was 48% lower than that of the unmodified FC. At this optimum dosage of 4.0% EP, the permeability pressure was at a maximum level of 1.4 MPa, whereas the permeability coefficient was at its lowest value of 0.75 × 10−9  mm/h. Internal pore structure and EP distribution were characterized using the scanning electron microscopy and indicated that a microgrid structure of the FC was formed internally, featuring an increase in the number of pores, a reduction in the average pore size, and a uniform pore size distribution. Similarly, surface energy measurements using the tensiometry method yielded maximum surface energy values at 4.0% EP content, which could be used to explain the reduced drying shrinkage and the enhanced impermeability characteristics of the modified FC.

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