Photoluminescence electrospun fibers were prepared from poly(fluorinated imide)s (PFIs) solutions... more Photoluminescence electrospun fibers were prepared from poly(fluorinated imide)s (PFIs) solutions. The studied PFIs included three fluorinated aromatic polyimides containing naphthalene pendant groups. The maximum UV–Vis absorption spectrums of the PFI fibers were located at 300–340 nm. The photoluminescence spectra indicated that the PFI fibers exhibited the following luminescence characteristics (excitation wavelength (nm); color): 330, blue; 450, olive green; 520, red. These phenomena could be attributed to the coexistence of naphthalene unit and fluorinated groups. The nanopores surface morphology of PFI fibers were studied using scanning electron microscopy and scanning probe microscopy. Surface wettability of PFI electrospun membranes were characterized by contact angle measurement. The contact angles on the electrospun poly(aryl ether) fibers for water and glycerol were in the range of 137.7–139.0° and 139.1–142.1°, respectively.
Two soluble poly(aryl ether)s were prepared conveniently from bis(4-hydroxy-3,5-dimethylphenyl)na... more Two soluble poly(aryl ether)s were prepared conveniently from bis(4-hydroxy-3,5-dimethylphenyl)naphthylmethane (1) and two activated dihalide monomers including 4,4′-difluorobenzophenone and bis(4-chlorophenyl)sulfone by an aromatic nucleophilic substitution. The bulky naphthyl and tetramethyl pendant groups in the polymer backbone could decrease the packing density and intermolecular interaction of macromolecular chain and make these poly(aryl ether)s show a good solubility. They all could be dissolved in CHCl3, CH2Cl2 and tetrahydrofuran at room temperature with a dissolvability of more than 10 wt%. Furthermore, the poly(aryl ether)s could be electrospun into microfiber (10–15 μm) with nanopores (200–350 nm). The morphologies of these fibers were characterized by scanning electron microscopy. The porous morphology on the fiber surface was also investigated using scanning probe microscope.
A new fluorinated diamine monomer containing naphthalene pendant group, bis(4-amino-3,5-difluorop... more A new fluorinated diamine monomer containing naphthalene pendant group, bis(4-amino-3,5-difluorophenyl)naphthylmethane (monomer 1), was synthesized from 1-naphthaldehyde and 2,6-difluoroaniline with trifluoromethanesulfonic acid at reflux. The novel poly(fluorinated imide)s (PFIs) were prepared via one-step polycondensation by monomer 1 and three aromatic dianhydrides including 4,4′-oxydiphthalic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, and 3,3′,4,4′-biphenyltetracarboxylic dianhydride in m-cresol, respectively. The obtained PFIs could be dissolved in a variety of organic solvents such as N-methyl-2-pyrrolidinone, N,N-dimetahylacetamide (DMAC), N,N-dimethylformamide, chloroform, and tetrahydrofuran at room temperature. The highest solubility of PFIs could even reach to 250 mg/mL in chloroform. The PFIs could be easily processed into flexible and tough films by casting onto glass from DMAC solution. The PFI films had a tensile strength, elongation at break, and tensile modulus in the range of 84–102 MPa, 8.7–12.8%, and 2.2–2.8 GPa, respectively. These polymers also showed excellent thermal stability with glass transition temperatures in the range of 326–352 °C, 10% weight loss temperatures in the range of 538–574 °C, and the weight residue more than 57% at 800 °C in nitrogen. Moreover, as for the optical properties, these PFIs exhibited a strong optical absorption in the ultraviolet region (290–370 nm) and photoluminescence in dilute chloroform solution or solid state.
A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetric... more A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetrical aromatic diamine, (4′-(4″-amino-2″-trifluoromethylphenoxy)-3′,5′-dimethylphenyl)(4-aminophenyl)-methanone (1), with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The PEKAs had inherent viscosities ranging from 0.43 to 0.65 dl/g. All the fluorinated PEKAs could be soluble in many polar organic solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). Flexible and tough polymer films could be prepared by casting from DMAc solvent. The PEKA films exhibited high optical transparency with a cutoff wavelength of 354-365 nm and good mechanical properties with tensile strengths of 78-98 MPa and elongations at break of 11.5-18.5%. They showed glass-transition temperatures in the range of 288−323°C and the onset decomposition temperatures in the range of 450−461°C in nitrogen atmosphere. Meanwhile, the PEKA films possessed low dielectric constants of 1.98-2.71 at 1 MHz and low moisture absorption (<2%). Due to their properties, the fluorinated PEKAs could be considered as photoelectric and microelectronic materials.
Novel fluorinated polyimides (PIs) were prepared from 9,9-bis(4-amino-3,5-difluorophenyl)fluorene... more Novel fluorinated polyimides (PIs) were prepared from 9,9-bis(4-amino-3,5-difluorophenyl)fluorene with three aromatic dianhydrides via a one-step high-temperature polycondensation procedure. These obtained PIs showed excellent solubility and could be readily soluble in a variety of organic solvents such as NMP, DMAc, DMF, CHCl 3 , CH 2 Cl 2 and THF. All the PIs could afford flexible and strong films with low dielectric constants (2.62-2.79 at 1 MHz) and low moisture absorptions (0.18-0.41%). Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 341-355 nm and transmittance higher than 80% at 450 nm. Meanwhile, these PIs possessed eminent thermal stability, with decomposition temperatures (T d ) above 570 C in both air and nitrogen atmospheres and glass transition temperatures (T g ) beyond 376 C. Moreover, these fluorinated PI films showed low surface free energy and hydro-oleophobic character. The contact angles on the films for water and glycerol were in the range of 102.3-107.9 and 94.0-100.3 , respectively. In comparison with the analogous PI non-containing fluorine group, these fluorinated PIs showed better solubility, higher optical transparency, lower dielectric constants and lower surface free energy.
Electrospun materials have been proposed for application for gas filtration, drug carriers, and t... more Electrospun materials have been proposed for application for gas filtration, drug carriers, and tissue engineering. The surface morphology of electrospun fibers is the key for consideration for the above applications, such as pore size on the fiber surface, surface area, and roughness. In this work, we investigated the influence of polymer/solvent properties on soluble polyimide (PI) fibers. The studied PIs included three fluorinated aromatic polyimides containing naphthalene pendant groups. By using various solvents we adjusted the size, shape, and structure of the fibers. As a result, PI electrospun fibers could be achieved with width around 10 μm. The rough and smooth surface morphologies were studied by scanning electron microscopy (SEM). Surface wettability of the electrospun fiber membranes were characterized by contact angle measurement. The contact angles on the electrospun PI fiber mats for water and glycerol were in the range of 137.6°–144.5° and 139.1°–143.6°, respectively. Moreover, the rough fiber surface could make the electrospun fiber membrane possess good adhesive force for liquids. The results suggest that we could widen the application of electrospun membranes through controlling the fiber morphology.
A series of novel polyimides (3a-d) were prepared from 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -diaminodi... more A series of novel polyimides (3a-d) were prepared from 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -diaminodiphenyl-4''-tert-butyltoluene (1) with four aromatic dianhydrides via a one-step high-temperature polycondensation procedure. The obtained polyimides showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most amide polar solvents and chlorinated solvents. Their films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range of 322-350 nm and the wavelength of 80% transparency in the range of 395-414 nm. They also showed low dielectric constant (2.72-2.91 at 1 MHz) and low water absorptions (0.37-0.62%). Moreover, these polyimides possessed high glass transition temperatures (T g ) (above 321 C) and good thermal stability with 10% weight loss temperatures in the range of 526-547 C in nitrogen atmosphere. In comparison with the analogous polyimides non-containing 3,3 0 ,5,5 0 -tetramethyl pendant groups, the resultant polyimides 3a-d showed better solubility, higher optical transparency and lower dielectric constant.
A novel aromatic diamine containing fluorine and trifluoromethyl groups, α-bis(4-amino-3,5-difluo... more A novel aromatic diamine containing fluorine and trifluoromethyl groups, α-bis(4-amino-3,5-difluorophenyl)-4-(trifluoromethyl)phenylmethane (1), was synthesized. Based on diamine 1 and four aromatic dianhydrides, a series of polyimides (PI) with high fluorine content were prepared via a one-step high-temperature polycondensation procedure. These obtained PIs were readily soluble in a variety of organic solvents, and they could afford flexible and strong films with low dielectric constants (2.57–2.84 at 1 MHz) and low moisture absorptions (0.23–0.45%). Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 311–354 nm and transmittance higher than 83% at 450 nm. Moreover, these PIs possessed eminent thermal stability and good mechanical properties.
Based on the synthesis of a rigid aromatic diamine, α,α-bis(4-aminophenyl)-4-(t-butyl)toluene (1)... more Based on the synthesis of a rigid aromatic diamine, α,α-bis(4-aminophenyl)-4-(t-butyl)toluene (1), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4′-oxydiphthalic dianhydride via a one-step high-temperature polycondensation. FT-IR, 1H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3. The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317°C and the temperature at 10% weight loss beyond 519°C in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character.
A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phe... more A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phenoxy)-naphthyl]-2-(4-carboxyphenyl)phthalazin-1-one (3) was successfully synthesized with high purity and high yields. A series of novel polyamides containing phthalazinone were prepared from the newly synthesized dicarboxylic acid with various aromatic diamines by means of the phosphorylation polycondensation reaction. Molecular weights of the obtained polyamides were evaluated viscometrically, and the inherent viscosities (ηinh) measured were in the range 0.54–0.69 dL/g. These polyamides were amorphous and readily soluble in many organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimetheylformamide, dimethyl sulfoxide, pyridine, and m-cresol etc., and they could easily be solution-cast into transparent, flexible films with good mechanical properties, with tensile strength ranging from 63.9 to 81.6 MPa and elongation at break from 7.2 to 11.4%. These polymers still kept good thermal stability with high-glass transition temperatures in the range of 283–338 °C, and the decomposition temperature in nitrogen for a 10% weight-loss temperatures in excess of 490 °C, and char yield at 800 °C in nitrogen ranged from 56 to 63%. Furthermore, the polyamides films were essentially colorless; their cut-off wavelengths were between 365 and 379 nm.
Nanocrystalline vanadium nitride (VN) was prepared by a direct thermal liquid-solid reaction betw... more Nanocrystalline vanadium nitride (VN) was prepared by a direct thermal liquid-solid reaction between vanadium chloride (VCl 4 ) and sodium azide (NaN 3 ) at 600°C. Characterized by XRD, TEM, XPS and PL, the composition and morphology of the product were confirmed. The possible reaction mechanism was also discussed.
Photoluminescence electrospun fibers were prepared from poly(fluorinated imide)s (PFIs) solutions... more Photoluminescence electrospun fibers were prepared from poly(fluorinated imide)s (PFIs) solutions. The studied PFIs included three fluorinated aromatic polyimides containing naphthalene pendant groups. The maximum UV–Vis absorption spectrums of the PFI fibers were located at 300–340 nm. The photoluminescence spectra indicated that the PFI fibers exhibited the following luminescence characteristics (excitation wavelength (nm); color): 330, blue; 450, olive green; 520, red. These phenomena could be attributed to the coexistence of naphthalene unit and fluorinated groups. The nanopores surface morphology of PFI fibers were studied using scanning electron microscopy and scanning probe microscopy. Surface wettability of PFI electrospun membranes were characterized by contact angle measurement. The contact angles on the electrospun poly(aryl ether) fibers for water and glycerol were in the range of 137.7–139.0° and 139.1–142.1°, respectively.
Two soluble poly(aryl ether)s were prepared conveniently from bis(4-hydroxy-3,5-dimethylphenyl)na... more Two soluble poly(aryl ether)s were prepared conveniently from bis(4-hydroxy-3,5-dimethylphenyl)naphthylmethane (1) and two activated dihalide monomers including 4,4′-difluorobenzophenone and bis(4-chlorophenyl)sulfone by an aromatic nucleophilic substitution. The bulky naphthyl and tetramethyl pendant groups in the polymer backbone could decrease the packing density and intermolecular interaction of macromolecular chain and make these poly(aryl ether)s show a good solubility. They all could be dissolved in CHCl3, CH2Cl2 and tetrahydrofuran at room temperature with a dissolvability of more than 10 wt%. Furthermore, the poly(aryl ether)s could be electrospun into microfiber (10–15 μm) with nanopores (200–350 nm). The morphologies of these fibers were characterized by scanning electron microscopy. The porous morphology on the fiber surface was also investigated using scanning probe microscope.
A new fluorinated diamine monomer containing naphthalene pendant group, bis(4-amino-3,5-difluorop... more A new fluorinated diamine monomer containing naphthalene pendant group, bis(4-amino-3,5-difluorophenyl)naphthylmethane (monomer 1), was synthesized from 1-naphthaldehyde and 2,6-difluoroaniline with trifluoromethanesulfonic acid at reflux. The novel poly(fluorinated imide)s (PFIs) were prepared via one-step polycondensation by monomer 1 and three aromatic dianhydrides including 4,4′-oxydiphthalic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, and 3,3′,4,4′-biphenyltetracarboxylic dianhydride in m-cresol, respectively. The obtained PFIs could be dissolved in a variety of organic solvents such as N-methyl-2-pyrrolidinone, N,N-dimetahylacetamide (DMAC), N,N-dimethylformamide, chloroform, and tetrahydrofuran at room temperature. The highest solubility of PFIs could even reach to 250 mg/mL in chloroform. The PFIs could be easily processed into flexible and tough films by casting onto glass from DMAC solution. The PFI films had a tensile strength, elongation at break, and tensile modulus in the range of 84–102 MPa, 8.7–12.8%, and 2.2–2.8 GPa, respectively. These polymers also showed excellent thermal stability with glass transition temperatures in the range of 326–352 °C, 10% weight loss temperatures in the range of 538–574 °C, and the weight residue more than 57% at 800 °C in nitrogen. Moreover, as for the optical properties, these PFIs exhibited a strong optical absorption in the ultraviolet region (290–370 nm) and photoluminescence in dilute chloroform solution or solid state.
A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetric... more A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetrical aromatic diamine, (4′-(4″-amino-2″-trifluoromethylphenoxy)-3′,5′-dimethylphenyl)(4-aminophenyl)-methanone (1), with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The PEKAs had inherent viscosities ranging from 0.43 to 0.65 dl/g. All the fluorinated PEKAs could be soluble in many polar organic solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). Flexible and tough polymer films could be prepared by casting from DMAc solvent. The PEKA films exhibited high optical transparency with a cutoff wavelength of 354-365 nm and good mechanical properties with tensile strengths of 78-98 MPa and elongations at break of 11.5-18.5%. They showed glass-transition temperatures in the range of 288−323°C and the onset decomposition temperatures in the range of 450−461°C in nitrogen atmosphere. Meanwhile, the PEKA films possessed low dielectric constants of 1.98-2.71 at 1 MHz and low moisture absorption (<2%). Due to their properties, the fluorinated PEKAs could be considered as photoelectric and microelectronic materials.
Novel fluorinated polyimides (PIs) were prepared from 9,9-bis(4-amino-3,5-difluorophenyl)fluorene... more Novel fluorinated polyimides (PIs) were prepared from 9,9-bis(4-amino-3,5-difluorophenyl)fluorene with three aromatic dianhydrides via a one-step high-temperature polycondensation procedure. These obtained PIs showed excellent solubility and could be readily soluble in a variety of organic solvents such as NMP, DMAc, DMF, CHCl 3 , CH 2 Cl 2 and THF. All the PIs could afford flexible and strong films with low dielectric constants (2.62-2.79 at 1 MHz) and low moisture absorptions (0.18-0.41%). Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 341-355 nm and transmittance higher than 80% at 450 nm. Meanwhile, these PIs possessed eminent thermal stability, with decomposition temperatures (T d ) above 570 C in both air and nitrogen atmospheres and glass transition temperatures (T g ) beyond 376 C. Moreover, these fluorinated PI films showed low surface free energy and hydro-oleophobic character. The contact angles on the films for water and glycerol were in the range of 102.3-107.9 and 94.0-100.3 , respectively. In comparison with the analogous PI non-containing fluorine group, these fluorinated PIs showed better solubility, higher optical transparency, lower dielectric constants and lower surface free energy.
Electrospun materials have been proposed for application for gas filtration, drug carriers, and t... more Electrospun materials have been proposed for application for gas filtration, drug carriers, and tissue engineering. The surface morphology of electrospun fibers is the key for consideration for the above applications, such as pore size on the fiber surface, surface area, and roughness. In this work, we investigated the influence of polymer/solvent properties on soluble polyimide (PI) fibers. The studied PIs included three fluorinated aromatic polyimides containing naphthalene pendant groups. By using various solvents we adjusted the size, shape, and structure of the fibers. As a result, PI electrospun fibers could be achieved with width around 10 μm. The rough and smooth surface morphologies were studied by scanning electron microscopy (SEM). Surface wettability of the electrospun fiber membranes were characterized by contact angle measurement. The contact angles on the electrospun PI fiber mats for water and glycerol were in the range of 137.6°–144.5° and 139.1°–143.6°, respectively. Moreover, the rough fiber surface could make the electrospun fiber membrane possess good adhesive force for liquids. The results suggest that we could widen the application of electrospun membranes through controlling the fiber morphology.
A series of novel polyimides (3a-d) were prepared from 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -diaminodi... more A series of novel polyimides (3a-d) were prepared from 3,3 0 ,5,5 0 -tetramethyl-4,4 0 -diaminodiphenyl-4''-tert-butyltoluene (1) with four aromatic dianhydrides via a one-step high-temperature polycondensation procedure. The obtained polyimides showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most amide polar solvents and chlorinated solvents. Their films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range of 322-350 nm and the wavelength of 80% transparency in the range of 395-414 nm. They also showed low dielectric constant (2.72-2.91 at 1 MHz) and low water absorptions (0.37-0.62%). Moreover, these polyimides possessed high glass transition temperatures (T g ) (above 321 C) and good thermal stability with 10% weight loss temperatures in the range of 526-547 C in nitrogen atmosphere. In comparison with the analogous polyimides non-containing 3,3 0 ,5,5 0 -tetramethyl pendant groups, the resultant polyimides 3a-d showed better solubility, higher optical transparency and lower dielectric constant.
A novel aromatic diamine containing fluorine and trifluoromethyl groups, α-bis(4-amino-3,5-difluo... more A novel aromatic diamine containing fluorine and trifluoromethyl groups, α-bis(4-amino-3,5-difluorophenyl)-4-(trifluoromethyl)phenylmethane (1), was synthesized. Based on diamine 1 and four aromatic dianhydrides, a series of polyimides (PI) with high fluorine content were prepared via a one-step high-temperature polycondensation procedure. These obtained PIs were readily soluble in a variety of organic solvents, and they could afford flexible and strong films with low dielectric constants (2.57–2.84 at 1 MHz) and low moisture absorptions (0.23–0.45%). Thin films of these PIs exhibited high optical transparency and light color, with the cutoff wavelength at 311–354 nm and transmittance higher than 83% at 450 nm. Moreover, these PIs possessed eminent thermal stability and good mechanical properties.
Based on the synthesis of a rigid aromatic diamine, α,α-bis(4-aminophenyl)-4-(t-butyl)toluene (1)... more Based on the synthesis of a rigid aromatic diamine, α,α-bis(4-aminophenyl)-4-(t-butyl)toluene (1), a novel polyimide (PI) 3 was prepared from this diamine monomer and 4,4′-oxydiphthalic dianhydride via a one-step high-temperature polycondensation. FT-IR, 1H NMR and elemental analysis were used to investigate the chemical structures of 1 and 3. The results confirmed that they agreed with the proposed structures for both 1 and 3 completely. The obtained PI 3 showed excellent solubility in most common solvents such as N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dichloromethane and tetrahydrofuran. The resulting strong and flexible film exhibited high thermal stability with the glass transition temperature at 317°C and the temperature at 10% weight loss beyond 519°C in both air and nitrogen atmospheres. Moreover, the film also showed high optical transparency, low dielectric constant (3.13 at 1 MHz), low water absorption (0.40%) and hydrophobic character.
A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phe... more A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phenoxy)-naphthyl]-2-(4-carboxyphenyl)phthalazin-1-one (3) was successfully synthesized with high purity and high yields. A series of novel polyamides containing phthalazinone were prepared from the newly synthesized dicarboxylic acid with various aromatic diamines by means of the phosphorylation polycondensation reaction. Molecular weights of the obtained polyamides were evaluated viscometrically, and the inherent viscosities (ηinh) measured were in the range 0.54–0.69 dL/g. These polyamides were amorphous and readily soluble in many organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimetheylformamide, dimethyl sulfoxide, pyridine, and m-cresol etc., and they could easily be solution-cast into transparent, flexible films with good mechanical properties, with tensile strength ranging from 63.9 to 81.6 MPa and elongation at break from 7.2 to 11.4%. These polymers still kept good thermal stability with high-glass transition temperatures in the range of 283–338 °C, and the decomposition temperature in nitrogen for a 10% weight-loss temperatures in excess of 490 °C, and char yield at 800 °C in nitrogen ranged from 56 to 63%. Furthermore, the polyamides films were essentially colorless; their cut-off wavelengths were between 365 and 379 nm.
Nanocrystalline vanadium nitride (VN) was prepared by a direct thermal liquid-solid reaction betw... more Nanocrystalline vanadium nitride (VN) was prepared by a direct thermal liquid-solid reaction between vanadium chloride (VCl 4 ) and sodium azide (NaN 3 ) at 600°C. Characterized by XRD, TEM, XPS and PL, the composition and morphology of the product were confirmed. The possible reaction mechanism was also discussed.
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