1,2,3-Triazole-Functionalized Polysulfone Synthesis through Microwave-Assisted Copper-Catalyzed Click Chemistry: A Highly Proton Conducting High Temperature Membrane

Abstract

Microwave heating holds all the aces regarding development of effective and environmentally friendly methods to perform chemical transformations. Coupling the benefits of microwave-enhanced chemistry with highly reliable copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry paves the way for a rapid and efficient synthesis procedure to afford high performance thermoplastic materials. We describe herein fast and high yielding synthesis of 1,2,3-triazole-functionalized polysulfone through microwave-assisted CuAAC as well as explore their potential as phosphoric acid doped polymer electrolyte membranes (PEM) for high temperature PEM fuel cells. Polymers with various degrees of substitution of the side-chain functionality of 1,4-substituted 1,2,3-triazole with alkyl and aryl pendant structures are prepared by sequential chloromethylation, azidation, and microwave-assisted CuAAC using a range of alkynes (1-pentyne, 1-nonyne, and phenylacetylene). The completeness of reaction at each step and the purity of the clicked polymers were confirmed by (1)H-(13)C NMR, DOSY-NMR and FTIR-ATR spectroscopies. The thermal and thermochemical properties of the modified polymers were characterized by differential scanning calorimetry and thermogravimetric analysis coupled with mass spectroscopy (TG-MS), respectively. TG-MS analysis demonstrated that the commencement of the thermal degradation takes place with the decomposition of the triazole ring while its substituents have critical influence on the initiation temperature. Polysulfone functionalized with 4-phenyl-1,2,3-triazole demonstrates significantly higher Tg, Td, and elastic modulus than the ones bearing 4-propyl-1,2,3-triazole and 4-heptyl-1,2,3-triazole groups. After doping with phosphoric acid, the functionalized polymers with acid doping level of 5 show promising performance with high proton conductivity in anhydrous conditions (in the range of 27-35 mS/cm) and satisfactorily high elastic modulus (in the range of 332-349 MPa).

Efficient internal plasticization of poly(vinyl chloride) via free radical copolymerization of vinyl chloride with an acrylate bearing a triazole phthalate mimic

“…The P(DEHT-HA) has a major weight loss step over the range of 290 ºC -540 ºC; with a maximum of degradation rate at 370 ºC. The onset temperature degradation (Ton) at 344 ºC is consistent with the degradation temperature of triazole rings bearing alkyl chains [48]. An initial weight loss between 25 ºC -150 ºC is also observed, which may be ascribed to the evaporation of residual solvent used in the purification step.…”

Synthesis of self-curable polysulfone containing pendant benzoxazine units via CuAAC click chemistry

“…The disappearance of the propargyl group signals at 73.1 and 78.2 ppm, and the appearance of triazole signals of PSU–CH 2 –Bz at 121.4 and 144.6 ppm indicated the successful CuAAC click reaction (Figure S2). [ 54 ]…”

Acidity effects of medium fluids on anhydrous proton conductivity of acid-swollen block polymer electrolyte membranes

“…To simplify the PEFC systems, PEMs exhibiting moderate proton conductivities even without humidication have been actively studied. [34][35][36][37][38][39][40][41][42][43] A representative example is a phosphoric acid (Pa)-doped polybenzimidazole (PBI) membrane that exhibits the low or moderate conductivities of 0.0056 S cm À1 at 130 C and 0.04 S cm À1 at 190 C. 44 Because of the lower conductivities, the PEM of Pa-doped PBI cannot be an alternative to the humidied Naon membrane. Efforts have also been made to enhance the anhydrous proton conductivity of PEMs composed of acid-doped PBI.…”