Zhen-Zhong Huang

Facile One‐Pot Synthesis of Oxazolidin‐2‐ones from Phenyl 2‐Hydroxyalkyl Selenides

Abstract A novel, convenient, efficient, three‐step, one‐pot synthesis of 2‐oxazolidinones from phenyl 2‐hydroxyalkyl selenides was developed. Using this methodology, 2‐oxazolidinones are obtained in good yields (76–85%) by reaction of phenyl 2‐hydroxyalkyl selenides with benzoyl isocyanate and subsequent oxidation/cyclization, followed by hydrolysis with hydrochloric acid solution.

New organosoluble poly(arylene ether nitrile) copolymers based on 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)xanthene

Several poly(arylene ether nitrile) (PAEN) copolymers containing multi-methyl and cardo xanthene groups were synthesized by nucleophilic substitution reaction of 2,6-difluorobenzonitrile with varying molar ratios of 9,9-bis(3,5-dimethyl-4-hydroxyphenyl)xanthene (BDMHPX) and hydroquinone (HQ) (80/20–40/60) in N-methyl-2-pyrrolidone (NMP) in the presence of anhydrous potassium carbonate. These new PAENs had inherent viscosities between 0.56 and 0.68 dL g–1, and their weight-average molecular weights and number-average molecular weights were in the range of 33,300–36,500 g mol−1 and 17,300–18,400 g mol−1, respectively. All polymers were amorphous and soluble in dipolar aprotic solvents such as NMP and N,N-dimethylacetamide and even in THF and chloroform at room temperature. These PAENs showed glass transition temperatures (Tgs) between 248°C and 289°C, and the Tg values were found to increase with increase of the BDMHPX content in the polymeric main. Thermogravimetric analysis showed that all PAENs were stable up to 400°C, with 5% weight loss temperatures ranging from 427°C to 448°C and char yields of 57–61% at 700°C under nitrogen atmosphere. All new PAENs could be cast into strong and flexible films with a tensile strength of 93–115 MPa, elongation at break of 10–12%, and tensile modulus of 3.3–3.5 GPa.

Synthesis and characterization of novel fluorinated pyridine-based polyimides derived from 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine and dianhydrides:

A series of new fluorinated pyridine-based polyimides (PIs) was synthesized by polycondensation of 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine with various aromatic dianhydrides in N,N-dimethylacetamide (DMAc) via the conventional two-step method. The inherent viscosities of the resulting poly(amic acid)s and PIs were 0.54–0.94 and 0.58–0.88 dLg−1, respectively. The obtained PIs were predominantly amorphous and soluble in polar solvents such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, and DMAc at room temperature or upon heating at 70°C. They also displayed good thermal stability with the glass transition temperature of 324–416°C, the temperature at 5% weight loss of 546–584°C, and the residue of 58–69% at 750°C under nitrogen, as well as outstanding mechanical properties with tensile strengths of 69132 MPa, tensile moduli of 1.1–2.0 GPa, and elongations at break of 7–27%. Meanwhile, these PI films had dielectric constants of 2.95–3.22 (1 MHz), low water uptake 0.44–0.71%, and high optical transparency with the ultraviolet cutoff wavelength in the 388–406 nm range and the wavelength of 80% transparency in the range of 550–680 nm.

Synthesis and characterization of new aromatic polyesters with a (4-phenoxyphenyl)phenylmethene linkage:

A series of new aromatic polyesters containing a (4-phenoxyphenyl)phenylmethene linkage were prepared by phase transfer-catalyzed interfacial polycondensation of 1,1-bis(4-hydroxyphenyl)-1-(4-phenoxyphenyl)-1-phenylmethane with terephthaloyl chloride, isophthaloyl chloride, and so on. The inherent viscosities of the polyesters ranged from 0.62 to 0.90 dL/g, while number-average molecular weights were in the range of 30,500–35,500 g/mol. All the polyarylates were readily soluble in organic solvents such as dichloromethane, chloroform (CDCl3), tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature, and could be cast into tough, transparent, and flexible films from their CDCl3 solutions. Wide-angle X-ray diffraction measurements revealed the amorphous nature of the polyarylates. These polymers showed glass transition temperatures (T gs) between 178°C and 240°C and decomposition temperatures at 10% weight loss ranging from 446°C to 483°C, while the initial degradation temperatures in the range of 410–435°C under nitrogen atmosphere. These new polyarylates exhibited higher T gs and better solubility than bisphenol A-based analogues.

Soluble copoly(pyridine ether imide)s derived from 6FDA, 1,4-bis(4-amino-2-trifluromethylphenoxy)benzene, and 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine

A series of new fluorinated copoly(pyridine ether imide)s were prepared by thermal imidization of polyamide acid derived from 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (BATB), 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine (TFMPBPP), and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) with various mole ratios of BATB and TFMPBPP ranged from 80/20 to 20/80. All copolyimides were amorphous and had excellent solubility in organic solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylformamide (DMF) at room temperature and displayed good thermal properties with glass transition temperature (T g) of 272°C–338°C, 5% weight loss temperature of 520°C–540°C, and the residue of 44–56% at 750°C in nitrogen. Meanwhile, the T g of the copolymers increased with an increase in the TFMPBPP component. Tough and flexible copolyimide films also exhibited outstanding mechanical properties with tensile strengths of 107.2–153.2 MPa, tensile moduli of 1.4–1.8 GPa, and elongations at break of 13.2–19.6%, low dielectric constants of 2.76–2.92 (1 MHz), and water uptake 0.32–0.62% as well as high optical transparency with the UV cutoff wavelength in the 371–386 nm range and the wavelength of 80% transparency in the range 459–498 nm.

New fluorinated aromatic polyamides based on N,N-bis(4-carboxyphenyl)-4-trifluoromethylaniline

A new aromatic diacid monomer, N,N-bis(4-carboxyphenyl)-4-trifluoromethylaniline, was synthesized by the substitution reaction of 4-trifluoromethylaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. Several polyamides with 4-trifluoromethyltriphenylamine 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 glass transition temperatures of 260–330°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 3.35–3.72 (100 Hz), low water uptake of 1.80–2.60%, and high transparency with an ultraviolet–visible absorption cutoff wavelength in the range of 378–390 nm. Cyclic voltammograms of the polyamide films cast onto an indium-tin oxide–coated glass substrate exhibited a reversible oxidation redox coupled with oxidation half-wave potentials (E 1/2) of 0.95–1.04 V versus silver/silver chloride in an acetonitrile solution.

Synthesis and characterization of novel fluorinated poly(ether imide)s containing pyridine and/or phenylphosphine oxide moieties

4-(4-Trifluoromethylphenyl)-2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]pyridine (9FPBAPP), as a new aromatic diamine, was prepared by a modified Chichibabin reaction of 4-(4-nitro-2-trifluoromethylphenoxy)acetophenone with 4-triflouromethylbenzaldehyde, followed by a catalytic reduction. A series of fluorinated poly(ether imide)s containing pyridine and/or phenylphosphine oxide moieties were prepared from bis(3-aminophenyl)phenylphosphine oxide (BAPPO), 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), and 9FPBAPP via a conventional two-step thermal imidization procedure with various mole ratios of BAPPO and 9FPBAPP. All the polymers were amorphous and soluble in common organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone and had T g’s of 277–285°C, 5% weight loss temperature of 521–550°C in nitrogen. Furthermore, high char yields and good limited oxygen index values indicated that these polymers exhibited good thermal stability and flame-retardant property. Tough and flexible polymer films also had good mechanical properties with tensile strengths of 75–99 MPa, tensile moduli of 1.1–1.6 GPa, and elongations at break of 12%–24% and low dielectric constants of 2.81–3.53 (1 MHz), as well as high optical transparency with the ultraviolet cutoff wavelength in the range of 350–384 nm.

Synthesis and characterization of soluble copoly(arylene ether ketone sulfone)s bearing xanthene moiety in the main chain

Several new poly(arylene ether ketone sulfone) (PEKS) copolymers containing xanthene moiety in the main chain were prepared by direct solution polycondensation reaction of 1,4-bis(4-fluorobenzoyl)benzene with varying mole ratios of 9,9-bis(4-hydroxyphenyl)xanthene and 4,4′-sulfonyldiphenol using sulfolane as solvent in the presence of anhydrous potassium carbonate. The introduction of xanthene and sulfone groups into the polymer chain resulted in an improvement in solubility of the polymers in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, sulfolane, pyridine, chloroform, and tetrahydrofuran. Thermal analysis revealed that the copolymers exhibited high glass transition temperatures (Tgs) of 208–221°C and excellent thermal stability associated with 5% weight loss temperatures ranging from 490°C to 521°C and 62–66% residual weight at 650°C under nitrogen atmosphere. All copolymers were amorphous and their solubility increased with an increase of sulfone content in the polymer backbone, while the Tgs and overall thermal stability appeared to decrease slightly. This new kind of xanthene-containing PEKS copolymers may be considered a good candidate for using as high-performance structural materials.

Preparation and characterization of novel soluble polyarylates derived from 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene with various bisphenols

A series of new polyarylates bearing cardo xanthene groups were synthesized by phase-transfer-catalyzed interfacial polycondensation of 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene with various bisphenols containing the isopropylidene, hexafluoroisopropylidene, 1-phenylethylidene, diphenylmethane, cyclohexane, and xanthene structures. High-molecular-weight polyarylates with number-average molecular weight and polydispersity index in the range of 30,100–35,300 and 1.82–2.17, respectively, exhibited high glass transition temperatures ranged from 226°C to 261°C, and their 10% weight loss temperatures were in the range of 421–452°C with char yields above 45% at 700°C in nitrogen. All the polyarylates were amorphous and readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and 1-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent, and flexible films with tensile strengths of 85.6–108.3 MPa, elongations at break of 2–3%, and tensile moduli of 7–9 GPa.

Preparation and characterization of new aromatic poly(ether ester)s bearing cardo xanthene groups

A series of new aromatic poly(ether ester)s containing cardo xanthene groups were synthesized by phase transfer–catalyzed interfacial polycondensation of three cardo bisphenols such as 9,9-bis(4-hydroxyphenyl)xanthene, 9,9-bis (4-hydroxy-3-methylphenyl)xanthene, and 9,9-bis(4-hydroxy-3,5-dimethylphenyl)xanthene with terephthaloyl chloride and isophthaloyl chloride. Inherent viscosities and number average molecular weights of the polymers were in the range 0.56–0.80 dL g−1 and 30,300–36,200, respectively. The resulting poly(ether ester)s exhibited high glass transition temperatures ranged from 208°C to 274°C, and their 10% weight loss temperatures were in the range of 440–458°C with char yields above 45% at 600°C under a nitrogen atmosphere. All the poly(ether ester)s were amorphous and readily soluble in organic solvents such as dichloromethane, chloroform, tetrahydrofuran, meta-cresol, pyridine, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methyl-2-pyrrolidinone at room temperature and could be cast into tough, transparent, and flexible films with tensile strengths of 68.2–86.8 MPa, elongations at break of 2–3%, and tensile moduli of 5.7–7.8 GPa.