scholarly journals Effect of Increased Ionic Liquid Uptake via Thermal Annealing on Mechanical Properties of Polyimide-Poly(ethylene glycol) Segmented Block Copolymer Membranes

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2143
Author(s):  
Gokcen A. Ciftcioglu ◽  
Curtis W. Frank
Keyword(s):  
Ionic Liquid ◽  
Block Copolymer ◽  
Ethylene Glycol ◽  
Functional Groups ◽  
Water Retention ◽  
Proton Exchange ◽  
Poly Ethylene Glycol ◽  
Practical Applications ◽  
Different Temperatures ◽  
Poly Ethylene

Proton exchange membranes (PEMs) suffer performance degradation under certain conditions—temperatures greater than 80 °C, relative humidity less than 50%, and water retention less than 22%. Novel materials are needed that have improved water retention, stability at higher temperatures, flexibility, conductivity, and the ability to function at low humidity. This work focuses on polyimide-poly(ethylene glycol) (PI-PEG) segmented block copolymer (SBC) membranes with high conductivity and mechanical strength. Membranes were prepared with one of two ionic liquids (ILs), either ethylammonium nitrate (EAN) or propylammonium nitrate (PAN), incorporated within the membrane structure to enhance the proton exchange capability. Ionic liquid uptake capacities were compared for two different temperatures, 25 and 60 °C. Then, conductivities were measured for a series of combinations of undoped or doped unannealed and undoped or doped annealed membranes. Stress and strain tests were performed for unannealed and thermally annealed undoped membranes. Later, these experiments were repeated for doped unannealed and thermally annealed. Mechanical and conductivity data were interpreted in the context of prior small angle X-ray scattering (SAXS) studies on similar materials. We have shown that varying the compositions of polyimide-poly(ethylene glycol) (PI-PEG) SBCs allowed the morphology in the system to be tuned. Since polyimides (PI) are made from the condensation of dianhydrides and diamines, this was accomplished using components having different functional groups. Dianhydrides having either fluorinated or oxygenated functional groups and diamines having either fluorinated or oxygenated diamines were used as well as mixtures of these species. Changing the morphology by creating macrophase separation elevated the IL uptake capacities, and in turn, increased their conductivities by a factor of three or more compared to Nafion 115. The stiffness of the membranes synthesized in this work was comparable to Nafion 115 and, thus, sufficient for practical applications.

scholarly journals Influence of Mixed Imide Composition and Thermal Annealing on Ionic Liquid Uptake and Conductivity of Polyimide-Poly(ethylene glycol) Segmented Block Copolymer Membranes

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7450
Author(s):  
Gokcen A. Ciftcioglu ◽  
Curtis W. Frank
Keyword(s):  
Mechanical Properties ◽  
Ionic Liquid ◽  
Block Copolymer ◽  
Ethylene Glycol ◽  
Young’S Modulus ◽  
Thermal Annealing ◽  
Young's Modulus ◽  
Poly Ethylene Glycol ◽  
Poly Ethylene ◽  
The Impact

Understanding the impact of different bridging groups in the two-step polymerization of poly(ethylene glycol) (PEG)-incorporated polyimide (PI) materials is significant. It is known that the proton exchange membranes (PEMs) used in industry today can experience performance degradation under rising temperature conditions. Many efforts have been devoted to overcoming this problem by improving the physical and mechanical properties that extend the hygrothermal life of a PEM. This work examines the effect of oxygenated and fluorinated bridging anhydrides in the production of PI-PEG PEMs. It is shown that the dianhydride identity and the amount incorporated in the synthesis influences the properties of the segmented block copolymer (SBC) membranes, such as increased ionic liquid uptake (ILU), enhanced conductivity and higher Young’s modulus favoring stiffness comparable to Nafion 115, an industrial standard. Investigations on the ionic conductivity of PI-PEG membranes were carried out to determine how thermal annealing would affect the material’s performance as an ion-exchange membrane. By applying a thermal annealing process at 60 °C for one hour, the conductivities of synthesized segmented block copolymer membranes values were increased. The effect of thermal annealing on the mechanical properties was also shown for the undoped SBC via measuring the change in the Young’s modulus. These higher ILU abilities and mechanical behavior changes are thought to arise from the interaction between PEG molecules and ethylammonium nitrate (EAN) ionic liquid (IL). In addition, higher interconnected routes provide a better ion-transfer environment within the membrane. It was found that the conductivity was increased by a factor of ten for undoped and a factor of two to seven for IL-doped membranes after thermal annealing.

scholarly journals Local Toxicity of Topically Administrated Thermoresponsive Systems: In Vitro Studies with In Vivo Correlation

2018 ◽  
Vol 47 (3) ◽  
pp. 426-432 ◽  
Author(s):  
Sivan Yogev ◽  
Ayelet Shabtay-Orbach ◽  
Abraham Nyska ◽  
Boaz Mizrahi
Keyword(s):  
Block Copolymer ◽  
Ethylene Glycol ◽  
Medical Devices ◽  
Poly Lactic Acid ◽  
Poly Ethylene Glycol ◽  
Thermoresponsive Polymers ◽  
Wide Range ◽  
Poly Ethylene

Thermoresponsive materials have the ability to respond to a small change in temperature—a property that makes them useful in a wide range of applications and medical devices. Although very promising, there is only little conclusive data about the cytotoxicity and tissue toxicity of these materials. This work studied the biocompatibility of three Food and Drug Administration approved thermoresponsive polymers: poly( N-isopropyl acrylamide), poly(ethylene glycol)-poly(propylene glycol)-poly(ethylene glycol) tri-block copolymer, and poly(lactic acid-co-glycolic acid) and poly(ethylene glycol) tri-block copolymer. Fibroblast NIH 3T3 and HaCaT keratinocyte cells were used for the cytotoxicity testing and a mouse model for the in vivo evaluation. In vivo results generally showed similar trends as the results seen in vitro, with all tested materials presenting a satisfactory biocompatibility in vivo. pNIPAM, however, showed the highest toxicity both in vitro and in vivo, which was explained by the release of harmful monomers and impurities. More data focusing on the biocompatibility of novel thermoresponsive biomaterials will facilitate the use of existing and future medical devices.

An Efficient One-Pot Four-Component Hantzsch Reaction to Prepare Hydroquinolines Catalyzed by a Poly(ethylene glycol) Bridged Dicationic Basic Ionic Liquid under Solvent-Free Conditions

2013 ◽  
Vol 781-784 ◽  
pp. 247-252
Author(s):  
Jun Luo ◽  
Tan Tan Xing ◽  
Ying Lei Wang ◽  
Jian Feng Ju
Keyword(s):  
Ionic Liquid ◽  
Ethylene Glycol ◽  
Solvent Free ◽  
Hantzsch Reaction ◽  
Poly Ethylene Glycol ◽  
One Pot ◽  
Solvent Free Conditions ◽  
Basic Ionic Liquid ◽  
Activity Loss ◽  
Poly Ethylene

A piperidine-functionalized poly (ethylene glycol) bridged dicationic ionic liquid PEG800-DPIL(Cl) was synthesized and applied to catalyze the four-component Hantzsch reaction under solvent-free conditions and afford hydroquinolines with high to excellent yields. PEG800-DPIL(Cl) could be recovered by simple workup and recycled for at least eight times without obvious activity loss.

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