Lin Fan

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Name: 范琳; L. Fan

Organization: Institute of Chemistry, Chinese Academy of Sciences , China

Department:

Title: Researcher/Professor(PhD)

TOPICS

Polymer

Polyimide

Chemicals
References

Transparent and conductive indium tin oxide/polyimide films prepared by high-temperature radio-frequency magnetron sputtering

Co-reporter:Yu Wen;Huan Liu;Shiyong Yang

Journal of Applied Polymer Science 2015 Volume 132( Issue 44) pp:

Publication Date(Web):

DOI:10.1002/app.42753

ABSTRACT

A highly transparent and thermally stable polyimide (PI) substrate was prepared and used for the fabrication of indium tin oxide (ITO)/PI films via radio-frequency magnetron sputtering at an elevated substrate temperature. The effect of the deposition conditions, that is, the oxygen flow rate, substrate temperature, sputtering power, and working pressure, on the optical and electrical properties of the ITO/PI films were investigated from the microstructural aspects. The results indicate that the optical and electrical properties of ITO were sensitive to the oxygen. Moreover, it was beneficial to the improvement of the ITO conductivity through the adoption of a high substrate temperature and sputtering power and a low working pressure in the deposition process. A two-step deposition method was developed in which a thick bulk ITO layer was overlapped by deposition on a thin seed ITO layer with a dense surface to prepare the highly transparent and conductive ITO/PI films. The ITO/PI film after annealing at 240°C gave a transmittance of 83% and a sheet resistance of 19.7 Ω/square. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42753.

Preparation of fluorinated polyimides with bulky structure and their gas separation performance correlated with microstructure

Co-reporter:Hui Tong, Chenchen Hu, Shiyong Yang, Yanping Ma, Hongxia Guo, Lin Fan

Polymer 2015 Volume 69() pp:138-147

Publication Date(Web):9 July 2015

DOI:10.1016/j.polymer.2015.05.045

•The fluorinated polyimides were synthesized from dianhydride 6FDA and aromatic diamines with bulky triptycene and pendent phenyl moieties.•The polyimide membranes, especially the GSPI-P ones revealed outstanding permeability coefficients combined with good selectivity especially for CO2/CH4 separation.•Large quantity of free volume combined with appropriate cavity size in polymeric membranes is beneficial to improve their permeability and selectivity simultaneously.The fluorinated polyimides with high fractional free volume were prepared from 6FDA and aromatic diamines with bulky triptycene and pendent phenyl moieties. These polymers showed excellent solubility, high thermal stabilities and outstanding mechanical properties. The correlation of gas separation performance with the microstructure of these polyimide membranes was investigated. The results indicated that the GSPI-P membranes based on the diamines with pendent phenyl moieties exhibited higher fractional free volumes than GSPI-T membranes derived from diamines with triptycene moieties; as a result, the former gave the much higher permeability coefficients. The gas permeability of these membranes is strongly depended on their free volume and also affected by fluorine content. The GSPI-P membranes also provided good selectivity for CO2/CH4 and CO2/N2 gas pairs because their appropriate cavity size is favorable to separate the CO2 from the other gases.

Preparation of thermal stable porous polyimide membranes by phase inversion process for lithium-ion battery

Co-reporter:Hejin Wang, Taipeng Wang, Shiyong Yang, Lin Fan

Polymer 2013 Volume 54(Issue 23) pp:6339-6348

Publication Date(Web):1 November 2013

DOI:10.1016/j.polymer.2013.09.036

The porous polyimide membranes were prepared by a wet phase inversion process based on the organo-soluble polyimide. The influence of coagulation bath composition and casting polymer solution concentration on the morphology of membranes was investigated. A series of spongy-like porous polyimide membranes with different porosity were obtained and characterized. These porous polyimide membranes exhibited excellent thermal stability and dimensional stability with the glass transition temperature of 274 °C and thermal shrinkage less than 1% after stored at 200 °C. All the porous polyimide membranes exhibited good wettability with electrolyte uptake of 190–378% due to their high surface polarity and high porosity. The discharge curves for the lithium-ion cells using porous polyimide membranes as separator displayed relatively flatter voltage plateaus than that for Celgard 2400 membrane and gave the discharge capacity of 129–131 mAh/g. The thermal stable porous polyimide membranes are favorable to be applied as separator in the lithium-ion cell and can be expected to provide excellent battery performance at elevated temperature.

Preparation and properties of pore-filling membranes based on sulfonated copolyimides and porous polyimide matrix

Co-reporter:Taipeng Wang, Fei Sun, Hejin Wang, Shiyong Yang, Lin Fan

Polymer 2012 Volume 53(Issue 15) pp:3154-3162

Publication Date(Web):6 July 2012

DOI:10.1016/j.polymer.2012.05.049

The porous polyimide films were prepared by a wet phase inversion process. The influence of coagulating non-solvent on morphology, pore size and porosity of porous films was investigated. A series of pore-filling sulfonated polyimide (PFSPI) membranes, which derived from a homogenous spongy-like porous polyimide film as matrix filled with sulfonated copolyimides, were prepared and characterized. These PFSPI membranes exhibited excellent thermal stability with desulfonation temperature of 283–330 °C and good oxidative stability in Fenton's agent due to the protective effect of porous polyimide matrix on the sulfonic acid groups. The swelling of PFSPI membranes could be effectively suppressed by the porous matrix, which leads to the excellent dimensional stability and good water stability of membranes. The PFSPI membranes exhibited high proton conductivity at elevated temperature. All the PFSPI membranes displayed better permselectivity as compared with Nafion 115, which is attributed to their much lower methanol permeability.Graphical abstract

Preparation and characterization of highly transparent and colorless semi-aromatic polyimide films derived from alicyclic dianhydride and aromatic diamines

Co-reporter:Lei Zhai, Shiyong Yang, Lin Fan

Polymer 2012 Volume 53(Issue 16) pp:3529-3539

Publication Date(Web):19 July 2012

DOI:10.1016/j.polymer.2012.05.047

A novel meta-substituted aromatic diamine containing trifluoromethyl and sulfonyl groups in the backbone, i.e., 2,2′-bis[4-(3-amino-5-trifluoromethylphenoxy)phenyl]sulfone (m-6FBAPS), was synthesized and characterized. A series of semi-aromatic polyimides were prepared from 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) and various aromatic diamines. These polymers exhibited excellent solubility, high thermal stabilities and good mechanical properties. All semi-aromatic polyimide films showed considerably improved optical transparency as comparing with traditional aromatic ones due to the incorporation of alicyclic moieties. They gave the UV cutoff wavelengths of 292–314 nm, transmittance at 450 nm > 91% and yellowness indices <3.8. The extremely transparent and entirely colorless films were obtained from the polymers incorporated with bulky electron-withdrawing trifluoromethyl and sulfonyl groups in diamine moieties, such as PI-2, PI-5 and PI-6. Their excellent optical properties are attributed to the distorted molecular conformation combined with the weakened electron-accepting and electron-donating properties of dianydride and diamines, which significantly restrained the formation of inter-/intra-molecular charge transfer interactions.

Synthesis and characterization of sulfonated polyimides bearing sulfonated aromatic pendant group for DMFC applications

Co-reporter:Fei Sun, Taipeng Wang, Shiyong Yang, Lin Fan

Polymer 2010 Volume 51(Issue 17) pp:3887-3898

Publication Date(Web):4 August 2010

DOI:10.1016/j.polymer.2010.06.005

A novel side-chain-type sulfonated aromatic diamine, 5-[1,1-bis(4-aminophenyl)-2,2,2- trifluoroethyl]-2-(4-sulfophenoxy)benzenesulfonic acid (BABSA) was synthesized and characterized. Two series of sulfonated polymides (SPI-N and SPI-B) were prepared from 1,4,5,8-naphthalene tetracarboxylic dianhydride (NTDA) or 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride (BNTDA), sulfonated diamine BABSA and various non-sulfonated aromatic diamines. The resulting sulfonated polyimide (SPI) membranes exhibited good dimensional stability with isotropic swelling of 7–22% and high thermal stability with desulfonation temperature of 283–330 °C. These membranes also displayed excellent oxidation stability and good water stability. The SPI membranes exhibited better permselectivity than Nafion 115 membrane due to their much lower methanol permeability. The ratios of proton conductivity to methanol permeability (Ф) for the SPI membranes were almost two to three times of that for Nafion 115. The SPI-N membranes exhibited excellent conducting performance with the proton conductivity higher than Nafion 115 as the temperature over 40 °C, which attributed to their good hydrophobic/hydrophilic microphase separation structure.

Phenylethynyl terminated oligoimides derived from 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride and their adhesive properties

Co-reporter:Hongjie Sun, Haitao Huo, Hao Nie, Shiyong Yang, Lin Fan

European Polymer Journal 2009 Volume 45(Issue 4) pp:1169-1178

Publication Date(Web):April 2009

DOI:10.1016/j.eurpolymj.2009.01.004

A series of phenylethynyl terminated oligoimides based on 3,3′,4,4′-diphenylsulfonetetracarboxylic dianhydride (DSDA), m-phenylene diamine (m-PDA) or/and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) with calculated molecular weight of 5000 g mol−1 were synthesized. The effect of molecular structure on solubility and melt viscosity of oligoimides as well as the thermal properties of cured polyimide resins was investigated. Experimental results indicated that the oligoimides have good solubility in strong polar solvents to afford homogeneous solutions with the solid content as high as 50 wt%. The oligoimides exhibited better solubility and lower minimum melt viscosity at relatively lower temperature with the incorporation of flexible 6FAPB. These oligoimides could be thermally cured at 320–380 °C to give thermosetted resins. The cured resins have good thermal stability with the glass transition temperatures of 278–329 °C and the onset decomposition temperatures higher than 500 °C. Adhesive properties of polyimides adhered to stainless steel at various conditions were evaluated by lap shear strength test. It was found that the LSS at room temperature increased with the molar ratio of 6FAPB increasing. The polyimides with combination of rigid and flexible structures exhibited good adhesive properties. With the increasing of curing temperature, the lap shear strength of polyimides at elevated temperature maintained at a high level due to the formation of strong bond.

Tribological behavior of short-fiber-reinforced polyimide composites under dry-sliding and water-lubricated conditions

Co-reporter:Jiansheng Chen;Junhong Jia;Huidi Zhou;Jianmin Chen;Shiyong Yang

Journal of Applied Polymer Science 2008 Volume 107( Issue 2) pp:788-796

Publication Date(Web):

DOI:10.1002/app.27127

Abstract

Polyimide composites reinforced with short-cut fibers such as carbon, glass, and quartz fibers were fabricated by the polymerization of monomer reactants process. The mechanical properties of the composites with different fiber contents were evaluated. The friction and wear properties of the polyimide and its composites were investigated under dry-sliding and water-lubricated conditions. The results indicated that the short-carbon-fiber-reinforced polyimide composites had better tensile and flexural strengths and improved tribological properties in comparison with glass-fiber- and quartz-fiber-reinforced polyimide composites. The incorporation of short carbon fibers into the polyimide contributed to decreases in the friction coefficient and wear rate under both dry and water-lubricated conditions and especially under water lubrication because of the boundary lubrication effect of water. The polyimide and its composites were characterized by plastic deformation, microcracking, and spalling under both dry and water-lubricated conditions, which were significantly abated under the water-lubricated condition. The glass and quartz fibers were easily abraded and broken; the broken fibers transferred to the mating metal surface and increased the surface roughness of mating stainless steel, which led to the wear rate increasing for the glass-fiber- and quartz-fiber-reinforced polyimide composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Synthesis and characterization of novel fluorinated polyimides derived from 4,4′-[2,2,2-trifluoro-1-(3-trifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines

Co-reporter:S. Y. Yang;Z. Y. Ge;D. X. Yin;J. G. Liu;Y. F. Li;L. Fan

Journal of Polymer Science Part A: Polymer Chemistry 2004 Volume 42(Issue 17) pp:4143-4152

Publication Date(Web):19 JUL 2004

DOI:10.1002/pola.20252

A novel fluorinated aromatic dianhydride, 4,4′-[2,2,2-trifluoro-1-(3-trifluoromethyl-phenyl)ethylidene]diphthalic anhydride (TFDA) was synthesized by coupling of 3′-trifluoromethyl-2,2,2-trifluoroacetophenone with o-xylene under the catalysis of trifluoromethanesulfonic acid, followed by oxidation of KMnO₄ and dehydration. A series of fluorinated aromatic polyimides derived from the novel fluorinated aromatic dianhydride TFDA with various aromatic diamines, such as p-phenylenediamine (p-PDA), 4,4′-oxydianiline (ODA), 1,4-bis(4-aminophenoxy)benzene (p-APB), 1,3-bis(4-amino-phenoxy)benzene (m-APB), 4-(4-aminophenoxy)-3-trifluoromethylphenylamine (3FODA) and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB), were prepared by polycondensation procedure. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m-cresol, as well as some of low boiling point organic solvents such as CHCl₃, THF, and acetone. Homogeneous and stable polyimide solutions with solid content as high as 35–40 wt % could be achieved, which were prepared by strong and flexible polyimide films or coatings. The polymer films have good thermal stability with the glass transition temperature of 232–322 °C, the temperature at 5% weight loss of 500–530 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 80.5–133.2 MPa as well as elongations at breakage of 7.1–12.6%. It was also found that the polyimide films derived from TFDA and fluorinated aromatic diamines possess low dielectric constants of 2.75–3.02, a low dissipation factor in the range of 1.27–4.50 × 10⁻³, and low moisture absorptions <1.3%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4143–4152, 2004