Jian-Wen Jiang

Synthesis and characterization of new poly(aryl ether ketone)s bearing (4-phenoxyphenyl)triphenylmethane moieties

1,1-Bis(4-hydroxyphenyl)-1-(4-phenoxyphenyl)-1-phenylmethane (BHPPPPM), a new bisphenol monomer, was synthesized with 65% yield from 4-benzoyl diphenyl ether in a one-pot, two-step synthetic procedure. Four new poly(aryl ether ketone)s (PAEKs) bearing (4-phenoxyphenyl)triphenylmethane moieties were prepared from BHPPPPM with four difluorinated aromatic ketones via a nucleophilic substitution reaction. The polycondensation proceeded in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the new PAEKs in nearly quantitative yields with inherent viscosities of 0.60–0.78 dL g−1. The resulting PAEKs having number-average molecular weights in the range of 29,500–34,200 g mol−1 with the polydispersity index ranged from 1.94 to 2.01 are all amorphous and show high glass transition temperatures ranging from 174°C to 196°C, excellent thermal stability, and the temperatures at the 5% weight loss are over 500°C with char yields above 60% at 700°C under nitrogen atmosphere. These new PAEKs are all soluble in polar aprotic solvents such as N-methyl-2-pyrrolidone and N,N′-dimethylacetamide and could also be dissolved in chloroform and tetrahydrofuran. All the polymers formed transparent, strong, and flexible films with tensile strengths of 78–85 MPa, tensile moduli of 1.9–2.4 GPa, and elongations at break of 7–10%.

Synthesis and characterization of novel aromatic polyamides containing 3-trifluoromethyl-substituted triphenylamine

ABSTRACT A new 3-trifluoromethyl-substituted triphenylamine-containing aromatic diacid monomer, N,N-bis(4-carboxyphenyl)-3-trifluoromethylaniline, was prepared by the substitution reaction of 3-trifluoromethylaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. Novel aromatic polyamides with 3-trifluoromethyl-substituted triphenylamine moieties were prepared from the diacid and various aromatic diamines via the direct phosphorylation polycondensation. All the polyamides were amorphous and readily soluble in many polar organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone, and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability with relatively high glass-transition temperatures (258–327°C), 10% weight-loss temperatures above 500°C, and char yields higher than 60% at 800°C in nitrogen. These polymers had low dielectric constants of 3.22–3.70 (100 Hz), low moisture absorption in the range of 1.75–2.58%, and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 375–395 nm range. Cyclic voltammograms of the polyamide films cast onto an indium tin oxide coated glass substrate exhibited a reversible oxidation redox couple with oxidation half-wave potentials (E1/2) of 0.95–1.00 V vs. Ag/AgCl in an acetonitrile solution.

New poly(ether benzoxazole)s containing xanthene cardo groups

A series of poly(ether benzoxazole)s (PEBOs) containing xanthene cardo groups were prepared via direct one-step condensation polymerization in poly(phosphoric acid/phosphorus pentoxide solution from 9,9-bis[4-(4-carboxyphenoxy)phenyl]xanthene and various bis(o-aminophenol)s. The resulting PEBOs with inherent viscosities of 0.87–1.08 dL g−1 were amorphous and exhibited glass transition temperatures in the range of 245–320°C. These new PEBOs exhibited improved solubility and could be processable from solution. Additionally, the obtained PEBOs showed excellent thermal stability, and did not show a significant weight loss up to 500°C in air or nitrogen, and the temperatures at 10% weight loss were in the range of 533–590°C in nitrogen and 508–570°C in air, with char yields more than 50% at 800°C in nitrogen. All the PEBOs formed strong and flexible films with tensile strengths of 53–80 MPa, tensile moduli of 2.3–2.6 GPa, and elongations at break of 3.2–3.7%.

Synthesis and properties of novel 9,9-diphenyl xanthene-based poly(aryl ether ketone)s with methyl substituents

A new bisphenol, 9,9-bis(4-hydroxy-3-methylphenyl)xanthene, was synthesized via a one-pot, two-step synthetic procedure in good yield and used for polymerization with difluorinated aromatic ketones in tetramethylene sulfone in the presence of anhydrous potassium carbonate to form several aromatic poly(ether ketone)s (PEKs) with 9,9-diphenylxanthene moieties and methyl substituents. The newly synthesized high-molecular-weight PEKs having number-average molecular weights in the range of 20,500–25,600 g mol−1 with the polydispersity index ranging from 1.9 to 2.1 were all amorphous and showed high glass transition temperatures in the range of 194–229.8°C, and the temperatures at the 5% weight loss were in the range of 420–445°C with char yields above 60% at 600°C under nitrogen atmosphere. All new PEKs are soluble in polar aprotic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, chloroform, pyridine, m-cresol, and tetrahydrofuran, and could form transparent, strong, and flexible films with tensile strengths of 66–74 MPa, Young’s moduli of 2.47–2.77 GPa, and elongations at break of 8–14%. In addition, these polymers had high transparency with an ultraviolet–visible absorption cutoff wavelength in the 352–356 nm range and low moisture absorption in the range of 0.41–0.56%.

Traceless Sulfone Linker for the Solid-Phase Organic Synthesis of 1-(E)-Styryl-4-substituted-1,2,3-triazoles

Abstract A novel, facile, solid-phase, organic synthesis of 1-(E)-styryl-4-substituted-1,2,3-triazoles in good yields and purities via traceless sulfone linker has been developed. Key steps involved in this synthetic procedure include (i) sulfone alkylation of sulfinate resin with (2-azido-1-iodoethyl)benzene, (ii) [3 + 2] cycloaddition with terminal alkynes in the presence of CuI, and (iii) traceless product release by base-mediated elimination process. GRAPHICAL ABSTRACT