Novel side-chain-type cardo poly(aryl ether sulfone) bearing pendant sulfoalkyl groups for proton exchange membranes

A Maximization of the Proton Conductivity of Sulfonated Poly(Ether Ether Ketone) with Grafted Segments Containing Multiple, Flexible Propanesulfonic Acid Groups

To enhance the proton conductivity of sulfonated poly(ether ether ketone) (SPEEK), proton-conducting groups are required to be covalently connected to SPEEK and form proton-conducting channels. Herein, SPEEK fully grafted with segments containing multiple, flexible propanesulfonic acid groups (MS-SPEEK-102) is successfully prepared. Compared with SPEEK, MS-SPEEK-102 exhibits a higher proton conductivity of 8.3 × 10^-2  S cm^-1 at 80 °C with 98% relative humidity, and consequently a greater power density of 0.530 W cm^-2 at 60 °C. These can be ascribed to the increased number of sulfonic acid groups, and ample, uninterrupted proton-conducting channels constructed by the movement of the maximum content, flexible side-chain segments. This approach offers an idea for obtaining a proton exchange membrane with good proton conductivity based on SPEEK.

A Low-Cost and High-Performance Sulfonated Polyimide Proton-Conductive Membrane for Vanadium Redox Flow/Static Batteries

A novel side-chain-type fluorinated sulfonated polyimide (s-FSPI) membrane is synthesized for vanadium redox batteries (VRBs) by high-temperature polycondensation and grafting reactions. The s-FSPI membrane has a vanadium ion permeability that is over an order of magnitude lower and has a proton selectivity that is 6.8 times higher compared to those of the Nafion 115 membrane. The s-FSPI membrane possesses superior chemical stability compared to most of the linear sulfonated aromatic polymer membranes reported for VRBs. Also, the vanadium redox flow/static batteries (VRFB/VRSB) assembled with the s-FSPI membranes exhibit stable battery performance over 100- and 300-time charge-discharge cycling tests, respectively, with significantly higher battery efficiencies and lower self-discharge rates than those with the Nafion 115 membranes. The excellent physicochemical properties and VRB performance of the s-FSPI membrane could be attributed to the specifically designed molecular structure with the hydrophobic trifluoromethyl groups and flexible sulfoalkyl pendants being introduced on the main chains of the membrane. Moreover, the cost of the s-FSPI membrane is only one-fourth that of the commercial Nafion 115 membrane. This work opens up new possibilities for fabricating high-performance proton-conductive membranes at low costs for VRBs.

Synthesis and physicochemical properties of sulfonated poly(aryl ether) PEMs containing phthalazinone and oxadiazole moieties

In this work, 2,5-bis(4-fluorophenyl)-1,3,4-oxadiazole (2F-Oz) is synthesized and successfully polymerized with 4-(4-hydroxyaryl)-phthalazin-1-one (DHPZ) through polycondensation to produce poly(ether 1,3,4-oxidiazole) containing phthalazinone units (PPEO) with intrinsic viscosity 1.54 dL g−1. A series of sulfonated poly(ether-1,3,4-oxidiazole)s (SPPEOs) with different degrees of sulfonation are prepared via postsulfonation reaction. The chemical structure of PPEO and SPPEOs was characterized through FT-IR and proton nuclear magnetic resonance, respectively. SPPEOs have excellent film-forming properties and readily dissolve in polar aprotic solvents, such as dimethyl sulfoxide, N-methyl-2-pyrrolidone (NMP), and so on. The water uptake of these SPPEO membranes with measured ion-exchange capacity of 1.13–1.61 mmol g−1 was 15.7–34.1% at 25°C and 17.9–59.8% at 60°C, and swelling ratio was 5.9–14.2% at 25°C and 6.6–18.1% at 60°C, respectively. The proton conductivity of SPPEO-1.61 is 0.045 S cm−1 at 30°C and 0.065 S cm−1 at 80°C, and the tensile strength of the SPPEO-1.61 is 48 MPa, and its elongation at break was 21%. The thermal and chemical stability of the SPPEOs is also examined.

A novel fuel cell membrane with high efficiency

A novel polymer containing an azo based ionic diol has been successfully fabricated as an electrolyte membrane to yield a good fuel cell performance in the whole range of current density.

Highly proton conducting fluorinated sulfonated poly(arylene ether sulfone) copolymers with side chain grafting

A series of new copolymers HPPQSH-XX PS were synthesized from preformed sulfonated ionomers HPPQSH-XX in order to get high proton conductivity along with other excellent properties.

Synthesis and Preliminary Properties of Novel Poly(aryl ether)s Containingβ-Naphthalene Pendant Group

Two novel poly(aryl ether)s containingβ-naphthalene pendant group were synthesized and the structures of these polymers were confirmed by1HNMR spectroscopy. The polymers exhibited good thermal stabilities with highTgof 256°C and 274°C, respectively. The polymers are soluble in common organic solvents, such as DMAc, DMSO, CH2Cl2, and CHCl3, and can be electrospun into microfiber (1–5 µm) with lots of nanopores (<100 nm) from CHCl3solution. These fibers showed high hydrophobicity, and the contact angle of fibers is above 120°.

Nanofiber mats electrospun from composite proton exchange membranes prepared from poly(aryl ether sulfone)s with pendant sulfonated aliphatic side chains

The electrospun nanofiber mats revealed high porosity and an interconnected open pore structure. The nanofibers are clearly visible and uniform throughout the composite membrane, which was completely pore-filled.

Sulfonated poly(ether sulfone ether ketone ketone)/sulfonated poly(ether sulfone) blend membranes with reduced methanol permeability

Proton exchange membranes were prepared by blending sulfonated poly(ether sulfone ether ketone ketone) (SPESEKK) with sulfonated poly(ether sulfone) (SPES). The morphology, tensile strength, proton conductivity and methanol permeability of the blend membranes were investigated. The scanning electron microscope and transmission electron microscope observation indicates the good dispersion of the SPES in SPESEKK polymer matrix. The addition of SPES also enhances the tensile strength of the SPESEKK membrane. The blend membrane shows lower methanol diffusivity and higher proton conductivity with comparison to the pure SPESEKK membrane, ascribing to the inhabitation of the player SPES to methanol permeation and facilitation of the increment of sulfonic acid groups to the proton transport. The SPESEKK/SPES 5 : 5 membrane exhibits an appreciable tensile strength of 52.3 MPa and a reduced methanol permeability of 6.6 × 10−7 cm2 s−1. This SPESEKK/SPES composite membrane shows a potential feasibility as a promising electrolyte for direct methanol fuel cells.