Browsing by Author "Tsai, Mei-Hui"

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An in situ fabrication process for highly electrical conductive polyimide/MWCNT composite films using 2,6-diaminoanthraquinone
(2013-10-18)
Huang, Yi-Chia
;
Lin, June-Hua
;
Tseng, I-Hsiang
;
Lo, An-Ya
;
Lo, Teng-Yuan
We present a valuable in situ fabrication process for synthesizing high electrical conductive polyimide/multiwalled carbon nanotube (PI/MWCNT) composite films. The success of this process was achieved the addition of 2,6-diaminoanthraquinone (DAAQ). The DAAQ is not only an excellent dispersion agent to stably disperse pristine MWCNTs in solvent but also a monomer to directly synthesize PI. The strong interaction between DAAQ with MWCNT was verified by FTIR, UV-Vis, Raman, and fluorescence spectra. The highest value of electrical conductivity of 55.6 S/cm are achieved by the PI composite containing 40 wt.% of MWCNT. Moreover, the electrical conductivity of this film further enhanced to 106 S/cm after the thermal compression process. The MWCNT content at the percolation threshold of conductivity is 0.50 wt.% (or 0.32 vol.%) and the critical exponent is equal to 2.52. The developed in situ fabrication process through DAAQ-derived molecules can also be applied to synthesize other polymers requiring diamine structure. (C) 2013 Published by Elsevier Ltd.
Co-doping with polysquaraine enhances the holographic optical data storage of PMMA/PQ photopolymers
(2011)
Ko, Cheng-Jung
;
Chang, Yeh-Lu
;
Hsiao, Yi-Nan
;
Chen, Po-Lin
;
Lin, Shiuan-Huei
In this study, we synthesised poly(3-octylpyrrole-co-squaric acid) (PSQ3), a polysquaraine, through the reaction of 3-octylpyrrole and squaric acid, and then co-doped it with phenanthrenequinone (PQ) into poly(methyl methacrylate) (PMMA) to improve the holographic data storage characteristics of the photopolymer. The photopolymers co-doped with relatively small amounts of PSQ3 exhibited greatly improved holographic recording characteristics, including superior diffraction efficiency and dynamic range (M#). Among the samples co-doped with PQ and PSQ3, the maximum diffraction efficiency reached 54.8% (cf. 9.0% for PMMA/PQ) without further downgrade and the value of M# reached 1.05 (cf. 0.46 for PMMA/PQ). Therefore, the holographic data storage characteristics of the photopolymer PMMA/PQ were improved through co-doping with PSQ3.
Effect of TiO2 on thermal and adhesive characteristics of poly(imide siloxane)/TiO2 hybrid films
(2012-05-05)
Ko, Cheng-Jung
;
Tseng, I-Hsiang
;
Whang, Wha-Tzong
;
Tsai, Mei-Hui
;
材料科學與工程學系
A novel poly(imide siloxane)/titania (PIS/TiO2) hybrid film was fabricated by sol-gel process via in situ formation of TiO2 within PIS matrix. Poly(amic acid siloxane) (PAAS) was prepared from 4,4'-oxydiphthalic anhydride, 2,2-bis [4-(4-aminophenoxy) phenyl] propane, and alpha,omega-bis(3-aminopropyl)polydimethylsiloxane (APPS). Chelating agent, acetylacetone, and catalyst-free polymerization were used to reduce the rate of hydrolysis of titanium alkoxide in the PAAS. X-ray photoelectron spectroscopy data showed that the presence of APPS promotes the Ti surface composition of PIS/TiO2 hybrid film. The effects of TiO2 and APPS contents on the characteristics of surface, thermostability, coefficient of thermal expansion (CTE), and the strength of adhesion were investigated. The presence of TiO2 on the surface of the hybrid films enhanced the adhesive strength at the interface of PIS/TiO2 hybrid film and copper foil. When more TiO2 was incorporated into the PIS matrix, the PIS/TiO2 hybrid film exhibited lower CTE while retaining favorable mechanical and thermal properties. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Enhancement of adhesion between copper foil and polyimide film containing thermally decomposable polystyrene particles
(2012-11-25)
Tsai, Mei-Hui
;
Huang, Yi-Chia
;
Tseng, I-Hsiang
;
Yu, Hsin-Pei
;
Lin, Yin-Kai
A facile method was developed to synthesize porous polyimide (PI) films with enhanced adhesion to Cu foil. Various amounts (0.14 wt %) of polystyrene (PS) spheres with the diameter of 250 nm were mixed with the PI precursor synthesized from pyromellitic dianhydride (PMDA) and 4,4'-oxydianiline in N,N'-dimethylacetamide. PS was decomposed during thermal imidization process to create the porous PI structure. The increase in surface area and surface roughness was observed from the obtained porous PI films and was a function of the PS content up to 4 wt %. A significant improvement in the adhesion strength between porous PI film and Cu foil, which was determined by 90 degrees peel test, was achieved. The adhesion strength of PI containing 4 wt % PS to Cu was 1.53 kgf/cm compared with pure PI of 1.08 kgf/cm. Meanwhile, the synthesized porous PI films exhibit sufficient mechanical strength and thermal stability for practical applications. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Holographic recording characteristics and physical mechanism of zinc methacrylate/nitroaniline-co-doped poly(methyl methacrylate)/9,10-phenanthrenequinone photopolymers
(2013-06-01)
Ko, Cheng-Jung
;
Chen, Po-Lin
;
Hsiao, Yi-Nan
;
Lin, Shiuan-Huei
;
Whang, Wha-Tzong
In this study we developed an approach to improve the characteristics of photopolymers for holographic data storage. Through codoping different compounds, N,N-dimethyl-4-nitroaniline (DMNA) and zinc methylacrylate (Zn(MA)2), into 9,10-phenanthrenequinone (PQ) doped poly(methyl methacrylate) (PMMA), the diffraction efficiency and the value of dynamic range (M#) have been progressed. We enhanced the diffraction efficiency (from 36.1 to 86.2%) and the dynamic range (M#, from 2.9 to 10.7) of PQ-doped PMMA through codoping with DMNA and Zn(MA)2. Using mass spectrometry and X-ray photoelectron spectroscopy, we investigated the mechanism behind the improvements in optical storage induced by the presence of Zn(MA)2 and DMNA in PMMA/PQ. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers
Significant improvement in the thermoelectric properties of zwitterionic polysquaraine composite films
(2013-09-16)
Ho, Mei-Chan
;
Chao, Ching-Hsun
;
Lo, An-Ya
;
Chen, Chun-Hua
;
Wu, Ren-Jye
In this study, the polysquaraine SQI(0.1), a zwitterionic pi-conjugated polymer, was adopted as the matrix for the preparation of flexible and freestanding films; the low band gap of this semiconducting polymer made it a natural choice for use as a thermoelectric (TE) polymer. To enhance their TE applications, both single-walled carbon nanotubes (SWNTs) and mesoporous carbon (i.e., CMK-3) were integrated into the SQI(0.1)-based films and the effects of doping with iodine were also investigated. Using scanning electron microscopy, the variations in morphology of these SQI(0.1)-based films were examined. Raman spectroscopy was used to study the pi-pi interactions between iodine and the carbon materials (Le., SWNT, CMK-3); X-ray diffraction and Raman spectroscopy to investigate the intercalation of the doped iodine in the composite films; and X-ray photoelectron spectroscopy to determine the valence state of the doped iodine. The TE properties of these materials were characterized in terms of the electrical conductivity (sigma), thermal conductivity (kappa), and Seebeck coefficient (S). The TE properties of the iodine-doped composite film prepared from SWNTs, CMK-3, and SQI(0.1) included a notable value of ZT (Figure of Merit) of 4.563 x 10(-3), which was 143% of that of the corresponding iodine-doped SQI(0.1) film. (c) 2013 Elsevier B.V. All rights reserved.
Thermal and mechanical properties of polyimide/nano-silica hybrid films
(2011-05-31)
Tsai, Mei-Hui
;
Huang, Yi-Chia
;
Tseng, I-Hsiang
;
Yu, Hsin-Pei
;
Lin, Yin-Kai
A novel route to synthesize polyimide (PI)/silica hybrid films with improved thermal and mechanical properties was developed. Low-molecular-weight poly(amic acid) (PAA), which is the precursor of PI, was successfully synthesized by controlling the molar ratio of monomers, [4,4'-(4,4'-isopropylidenediphenoxy) bis(phthalic anhydride)] (IDPA) and 2,2'-bis(4-(4-aminophenoxy)phenyl)propane (BAPP). The PM with its low-molecule-weight feature showed good compatibility with silica-sol and dispersed well within the network of silica-sol. Silica nanoparticles with an average size of 20 nm were obtained without adding coupling agents and dispersed homogenously within the resulting PI/silica hybrid films due to the hydrogen bonding between Si-OH groups and C=O in imide rings of polyimide. The improvement in the storage modulus and the coefficient of thermal expansion (CTE) by hybrid films was revealed. With the presence of 50 wt.% silica in hybrid films, the storage modulus was 5857 MPa and the CTE was 18.1 ppm/degrees C. compared with 1620 MPa and 76.5 ppm/degrees C for pure PI. Most importantly, the transmission at 550 nm was 81.4% for the hybrid film with 50 wt.% silica, which is close to 87.5% for pure PI. The CTE of the hybrid film dropped to the level comparable with that of copper without sacrificing its transparency, which was associated with the well-dispersed silica nanoparticles and the semi-interpenetrating polymer network (semi-IPN) structure within the PI matrix. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.