Phthalonitrile end-capped sulfonated polyarylene ether nitriles for low-swelling proton exchange membranes

Study on preparation and performance of sulfonated polyaryl ether nitrile@Im-MOF-801(SPEN@Im-MOF-801)composite proton exchange membrane

Sulfonated polyaryl ether nitrile (SPEN) is some of the most viable novel materials to replace the Nafion membrane. To resolve the issue of proton conductivity in fuel cells with poor sulfonation degree polyaryl ether nitrile cell membranes. A metal-organic structure (MOF-801) was added as a filler, and imidazole was loaded by the MOF-801 structural skeleton via a chemical ligand to improve the SPEN’s proton conductivity. The expected chemical structure of im-MOF-801 and SPEN@Im-MOF-801 was confirmed by using FTIR and 1H NMR. Loading im-MOF-801 into SPEN resulted in SPEN@Im-MOF-801 composite proton exchange membranes. The impacts of the metal-organic framework on the performance of SPEN composite membranes were explored by assessing their mechanical characteristics, thermal stability, proton conductivity, and methanol permeability. The results show that the composite has outstanding thermal and mechanical stability. The tensile strength of membranes rose from 25.92 MPa to 39.34 MPa compared to the castings SPEN membrane, which was attributable to creating a hydrogen-bonding network between im-MOF-801 and SPEN, which boosted intermolecular forces. The carboxyl and hydroxyl groups in im-MOF-801 gave additional acceptors and donors that expanded the proton conductivity of SPEN, which was 16.19 ×10−2 S·cm−1 and expanded continuously, followed by a decrease with increasing temperature. Proton conductivity of SPEN@Im-MOF-801–3 and im-MOF-801–9 comes to 18.46 and 17.07 ×10−2 S·cm−1 at 80°C. Moreover, the methanol penetration of SPEN@Im-MOF-801 decreased reliably (from 5.32 to 1.02 ×10−7 S·cm−1 which was much lower than that of the Nafion film 21.87 ×10−7 S·cm−1). Subsequently, the most noteworthy selectivity of SPEN@Im-MOF-801–3 comes to 2.93×105 S·cm−3·s−1, which is approximately 8.9 times higher than that of Nafion (0.33×105 S·cm−3·s−1). The comes about demonstrates that these composites have potential applications in DMFCs.

Catalytic Polymerization of Phthalonitrile Resins by Carborane with Enhanced Thermal Oxidation Resistance: Experimental and Molecular Simulation

Biphenyl phthalonitrile (BPh) resins with good thermal and thermo-oxidative stability demonstrate great application potential in aerospace and national defense industries. However, BPh monomer has a high melting point, poor solubility, slow curing speed and high curing temperature. It is difficult to control the polymerization process to obtain the resins with high performance. Here, a BPh prepolymer (BPh-Q) was prepared by reacting 1,7-bis(hydroxymethyl)-m-carborane (QCB) with BPh monomers. The BPh-Q exhibited much better solubility, faster curing speed and lower curing temperature compared with pure BPh and BPh modified with bisphenol A (BPh-B, a common prepolymer of BPh). Thus, the polymerization process of BPh was greatly accelerated at a low temperature, resulting in a BPh resin with enhanced thermostability and oxidation resistance. The experimental and theoretical models revealed the promotion effect of B-H bond on the curing reaction of phthalonitrile via Markovnikov addition reaction due to the special steric structure of carborane. This study provided an efficient method to obtain low-temperature curing phthalonitrile resins with high thermal and thermo-oxidative resistance, which would be potentially useful for the preparation of high-performance cyanide resin-based composites.

Comb-shaped cardo poly(arylene ether nitrile sulfone) anion exchange membranes: significant impact of nitrile group content on morphology and properties

A series of comb-shaped cardo poly(arylene ether nitrile sulfone) (CCPENS-x) materials were synthesized by varying the content of nitrile groups as anion exchange membranes (AEMs). The well-designed architecture of cardo-based main chains and comb-shaped C10 long alkyl side chains bearing imidazolium groups was responsible for the clear microphase-separated morphologies, as confirmed by atomic force microscopy. The ion exchange capacity (IEC) of the AEMs ranged from 1.56 to 1.65 meq. g⁻¹. With strong dipole interchain interactions, the effects of nitrile groups on the membrane morphology and properties were investigated. With the nitrile group content increasing from CCPENS-0.2 to CCPENS-0.8, CCPENS-x revealed larger and more interconnected ionic domains to form more efficient ion-transport channels, thus increasing the corresponding ionic conductivity from 25.8 to 39.5 mS cm⁻¹ at 30 °C and 58.6 to 83 mS cm⁻¹ at 80 °C. Furthermore, CCPENS-x with a higher content of nitrile groups also exhibited lower water uptake (WU) and swelling ratio (SR), and better mechanical properties and thermal stability. This work presents a promising strategy for enhancing the performance of AEMs.

A series of comb-shaped cardo poly(arylene ether nitrile sulfone) (CCPENS-x) materials were synthesized by varying the content of nitrile groups as anion exchange membranes (AEMs).

Synthesis and Characterization of Sulfonated Graphene Oxide Reinforced Sulfonated Poly (Ether Ether Ketone) (SPEEK) Composites for Proton Exchange Membrane Materials

As a clean energy utilization device, full cell is gaining more and more attention. Proton exchange membrane (PEM) is a key component of the full cell. The commercial-sulfonated, tetrafluoroethylene-based fluoropolymer-copolymer (Nafion) membrane exhibits excellent proton conductivity under a fully humidified environment. However, it also has some disadvantages in practice, such as high fuel permeability, a complex synthesis process, and high cost. To overcome these disadvantages, a low-cost and novel membrane was developed. The sulfonated poly (ether ether ketone) (SPEEK) was selected as the base material of the proton exchange membrane. Sulfonated graphene (SG) was cross-linked with SPEEK through the elimination reaction of hydrogen bonds. It was found that the sulfonic acid groups and hydrophilic oxygen groups increased obviously in the resultant membrane. Compared with the pure SPEEK membrane, the SG-reinforced membrane exhibited better proton conductivity and methanol permeability prevention. The results indicate that the SG/SPEEK could be applied as a new proton exchange membrane in fuel cells.