Browsing by Author "Ho, Ko-Shan"

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Characterizations on the amidized multiwalled carbon nanotubes grafted with polyaniline via in situ polymerization
(2012-06-15)
Wu, Yi-Jhen
;
Chao, Liang
;
Ho, Ko-Shan
;
Huang, Ying-Jie
;
Huang, Yu-Lan
A multiwalled carbon nanotubes (MWCNTs) were carboxylated after refluxing with sulfuric and nitric acids. These attached carboxylic acid groups were further condensated with o-phenylene diamine into amide catalyzed by dicyclohexyl carbodiimide (DCC). The obtained amidized MWCNTs were in situ-polymerized with aniline monomers to graft a conducting polyaniline (PANI) onto MWCNT (ES-g-MWCNTs) through the polymerization occurring in the ortho- and meta-positions. The reduced conductivity of the MWCNT after carboxylation can be recovered after grafting with PANI, which owns a strong ?max at the near infrared region due to the extended conjugation from MWCNTs to PANI. Transmission electronic microscopic pictures show a gradual broadening of the MWCNT diameter after carboxylation, amidization, and polymerization. The weight loss from the thermogravimetric thermograms due to the carboxylations of MWCNTs, amidized MWCNTs, and the PANI grafted MWCNTs into CO2 can be used to estimate the degree of carboxylation, amidization, and grafting of PANI. The degree of carboxylation of MWCNT calculated from ESCA spectrum is around 23% close to that estimated from TGA thermogram. The doping level of redoped PANI-grafted MWCNT is found to be 27.78% much less than the maximum 50% of neat PANI. (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Conducting polymer blends prepared from polyaniline with n-dodecylbenzenesulfonic acid zinc salt as the secondary dopant
(2008-06-15)
Chao, Liang
;
Han, Yu-Kai
;
Hiseh, Bi-Zen
;
Huang, Ying-Jie
;
Hsieh, Tar-Hwa
A red-shift of the UV-vis spectra of n-dodecylbenzenesulfonic acid doped polyaniline (PANI (DBSA)(0.5)), resulting from the secondary doping of polyaniline backbones, was found in the presence of n-dodecylbenzenesulfonic acid zinc salt (Zn(DBS)(2)). It is proved to behave as steric hindrance spacers to induce the extension of the conjugation length through the straightening effect on the polyaniline backbones and the obtained mixtures (PANI(DBSA)(0.5) plus Zn(DBS)(2)) can be used as master batch materials (MB-13) for blending with regular polypropylene polymer (PP). The thermal degradation accompanied with loss of conductivity for MB-13 can be delayed to over 250 degrees C.when enough Zn(DBS)(2) was secondarily doped on PANI(DBSA)0.5., which allow the performance of its blending with other nonconducting/regular polymers possible. Below 80 rpm, increasing shear rates would induce higher viscosity difference between the MB-13 and PP matrix, resulting in elongation of MB-13 in the PP matrix and higher conductivities of the polyblends. The deviation from the Taylor equation, which is used to estimate the degree of elongation for a polyblend, started when shear rate is over 80 rpm. The leakage of Zn(DBS)(2) out of MB-13 can be confirmed by comparing the DSC thermograms and X-ray diffraction patterns with that of neat PP. Gradual deformation for the conductive fillers (MB-13) and a well-defined and expanded layered structure can be found when processing time is below 15 min with 60 rpm shear rate. The layers started to shrink back after 15 min of procession with the loss of the Zn(DBS)(2) from MB-13 in the PP matrix. (c) 2008 Wiley Periodicals, Inc.
Degradation induced variation of LC transition of poly(n-undecyl isocyanate)
(2008-05-01)
Hsieh, Bi-Zen
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Chuang, Hung-Yi
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Chao, Liang
;
Huang, Ying-Jie
;
Tseng, Po-Hao
The first-order thermal transitions including side-chain melting, crystal-LC, biphasic chimney-like, and isotropic transitions of poly(n-undecyl isocyanate) (PUDIC) were investigated by varying its thermal history. After annealing at 140 degrees C for different periods of time, it leads to different degrees of backbiting degradation into n-undecyl isocyanurate trimer which behaves as a solvent for the rest non-degraded/rigid PUDIC to change into a lyotropic LC from thermotropic transition. Based on the degree of degradation, various amounts of trimers are present and the PUDIC demonstrates different types of thermal transitions found in DSC thermograms due to the variation of the non-degraded PUDIC concentration in solvent trimers. Finally, a phase diagram includes all types of crystallines, LC, and isotropic regions can be drawn according to the DSC thermograms. (C) 2008 Elsevier Ltd. All rights reserved.
Effect of Bridging Groups on Sulfonated Poly(imide-Siloxane) for Application in Proton Exchange Membrane
(2010-04-01)
Lee, Chi-Hung
;
Chen, Jia-Ru
;
Shiu, Hung-Wei
;
Ho, Ko-Shan
;
Wu, Shinn-Dar
A series of six-membered sulfonated poly(imide-siloxane)s (SPIs) was synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), aminopropyl-terminated polydimethylsiloxane (PDMS) 2,2-benzidinedisulfonic acid (BDSA), as the sulfonation target diamine groups, and various nonsulfonated diamine monomers behaving as bridging groups. The structure-property relationship of SPI-SXx membranes is discussed in detail according to the chemical structure of the various nonsulfonated diamines of the SPI-SXx membranes from the viewpoints of proton conductivity, ion exchange capacity (IEC), and membrane properties (water uptake and membrane swelling) at equal PDMS content SPI-SXx. The PDMS was introduced to enhance the proton conductivity and water uptake attributed from the high flexibility of the siloxane segments. The conductivity and water uptake of angled SPI-SXm and oxydianiline-based SPI-SX membranes (SPI-SXO) are greater than those prepared from diaminodiphenylmethane-based SPI-SX membranes (SPI-SXD) at a given IEC. These differences resulted from the increased number of entanglements of the SPI-SXx membrane. The SPI-SXD showed almost isotropically dimensional changes with the increase in water uptake, and the volume were slightly smaller than those estimated from the additivity rule. Free volume in the SPI-SXx increased with the increase in bulky irregular packing in nonsulfonated segments, which augmented the water uptake and, in turn, the conductivity of the polymer. With the increase in temperature, conductivity increased more rapidly in SPI-SXx than in Nafion 117. Microscopic analyses revealed that these smaller (<10 nm) and well-dispersed hydrophilic domains contribute to better proton conducting properties. The new sulfonated poly(imide-siloxane) s have proved to be a possible candidate as the polymer electrolyte membrane for polymer electrolyte fuel cells (PEFCs) and direct methanol fuel cells (DMFCs). [DOI: 10.1115/1.3200906]
Formation and degradation mechanism of a novel nanofibrous polyaniline
(2009-06-01)
Ho, Ko-Shan
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Han, Yu-Kai
;
Tuan, Yu-Tsung
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Huang, Ying-Jie
;
Wang, Yen-Zen
A nanotubular, nanofibrous polyaniline (PANINT) was prepared from an emulsion polymerization in the presence of n-dodecylbenzene sulfonic (DBSA) and hydrochloric acids. The building of the tubular structure based on the tubular micelles from the accumulation (pile up) of micelles at high surfactant concentration, leading to early stage of centipede-like and eventual tubular morphologies. The PANINT molecule owning a highly conjugated backbone demonstrated a free carrier-tail in the near-IR region due to its helical conformation. After dedoping, the once empty PANINT with only some complexed DBSA inside shrank into solid rods, after the removal of the complexed DBSA. As a result, the solid rods were filled with helical emeradine base (nano-EB) molecules associated with inter-molecular H-bonding. The solid rods of nano-EB went on crosslinking and carbonization after 200-300 degrees C by opening the quinoid rings and the inter-molecular H-bondings were destroyed with nano-EB molecules crosslinking into ladder-like structure. When temperature was over 300 degrees C and below 800 degrees C, carbonization enhanced by de-ammoniaization, causing a significant weight loss. However, the cleavage of aromatic rings into aliphatic pieces occurred after 800 degrees C, which chopped the ladder-like, strips of carbonized nano-EB sheets into small pieces of nano-particles. The conductivity of the pyrolyzed nano-EB was found to be around 10(-5) s/cm, 10,000 times higher than the neat nano-EB of 10(-9) s/cm due to the carbonization. (C) 2009 Elsevier B.V. All rights reserved.
Formation mechanism of a nanotubular polyanilines prepared by an emulsion polymerization without organic solvent
(2008-09-09)
Hsieh, Bi-Zen
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Chuang, Hung-Yi
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Chao, Liang
;
Li, Yu-Jen
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Huang, Ying-Jie
A nanotubular polyaniline (PANINT) was prepared from a simple emulsified polymerization method without oil solvent present. A mechanism of the formation of the nano-fibers/tubes was proposed to show that it started with the connecting arrangement of the neighboring anilinium micelles before and during polymerization, which resulted in the formation of the intermediate morphology of centipedes converting into rod-like nanofibers later. The obtained PANINTs displayed not only nanofibrous structure but owned an unusual dispersing behavior in toluene. SEM and TEM showed the dendrite-like networks of nanofibers connected and glued together by the free (not complexed to polyaniline backbone) n-dodecylbenzene sulfonic acid (DBSA) molecules. After removing the free DBSA by acetone, the clear/well-defined empty nanotubes can be seen from TEM in the magnified micrograph. The Atomic force microscopic (AFM) microgaphs demonstrated the cottage like surface morphology of the un-perturbed PANINTs and the morphology was converted to an anisotropic/oriented rods after rubbing on the wet/ cast PANINTs' dispersion of toluene before entire evaporation. (c) 2008 Published by Elsevier Ltd.
Influence of Sulfonationity of Epoxy-Based Semi-Interpenetrating Polymer Networks of Sulfonated Polyimides as Proton Exchange Membranes on the Performance of Fuel Cell Application
(2010-04-01)
Wang, Yen-Zen
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Ho, Ko-Shan
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Wu, Shinn-Dar
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Hsieh, Kuo-Huang
;
Lee, Chi-Hung
A novel epoxy-based semi-interpenetrating polymer networks membrane (SPIX-EP40) as the proton exchange membrane was prepared by a flexible epoxy network with sulfonated polyimide. A series of sulfonated polyamic acid (SPAA) were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2-benzidinedisulfonic acid (BDSA) and non-sulfonated diamines, such as 4,4'-diaminodiphenyl sulfone. Solid-state (13)C nuclear magnetic resonance spectra and Fourier transform infrared spectroscopy were used to verify the synchronization of the imidization of SPAA and the crosslinking reactions of epoxy. The sulfonationity of the copolymers was regulated through a variation in the molar ratio of BDSA to diamine. These membranes owned a good thermal stability and exhibited high proton conductivity that was measured as a function of temperature. The resulting SPI0.7-EP40 and SPI0.8-EP40, at 100% relative humidity, displayed proton conductivities higher than those of Nafion (R) 117. The membranes displayed higher conductivities than Nafion (R) membranes because of owning higher activational energies and higher ion exchange capacities. An isotropic swelling phenomenon in water was found for the membrane. From the results of water uptake and the microstructure analyses using transmission electron microscopy (TEM) on different sulfonated levels, it was found that the number of water clusters in SPIX-EP40 membranes increased as the increasing water uptake and the size of water cluster were changed with the sulfonation levels. TEM confirmed the widespread and well-connected hydrophilic domains, demonstrating the presence of the favorable proton-transporting performances of the SPIX-EP40 membrane. [DOI: 10.1115/1.3177383]
Shearing effects on the conducting polymer blends
(2008-06-01)
Chao, Liang
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Huang, Ying-Jie
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Han, Yu-Kai
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Tseng, Po-Hao
;
Hsieh, Tar-Hwa
To obtain a highly conductive polyblend based on doped polyaniline, an zinc salt based conductive master batch material (MB-13) made from mixing zinc n-dodecylbenzene sulfonate (Zn (DBS)(2)) and n-dodecylbenzene sulfonic acid (HDBSA) polyaniline (PANI(DBSA)(0.5)) together was compounded with PP in a melt-mixer varying the processing conditions. The SEM pictures show the morphologies of the polyblends were phase-separated into strips of elongated MB-13 for all samples. The elongation was first enhanced at shear rates ranged from 20 to 60 rpm. A shear rate of 60 rpm at 180 degrees C can elongate the conductive master batch phases (filler) to obtain both the highest aspect ratio and least resistance by keeping the secondary dopants of Zn (DBS)(2) stay within MB-13 from losing its conductivity and deformability.
Synthesis and characterization of a novel proton-exchange membrane for fuel cells operating at high temperatures and low Humidities
(2008-03-15)
Chaung, Ching-Nan
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Chao, Liang
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Huang, Ying-Jie
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Hsieh, Tar-Hwa
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Chuang, Hung-Yi
The synthesis of a p-toluidine/formal dehyde (PTF) resin was performed, and the effects of the molar ratio of the individual monomers and the polymerization conditions on the structure of the PTF resin were studied. Fourier transform infrared and C-13-NMR spectra were used to characterize the PTF. Wide-angle X-ray diffraction patterns revealed the crystalline structures of various PTFs. Polarized optical microscopy revealed that the molar ratio of the monomers had a strong effect on the crystalline morphologies. A longer polymerization time turned out a polymer with a higher intrinsic viscosity and molecular weight, which led to differences in the proton conductivity. All of the PTFs showed a higher proton conductivity than a commercial Nafion membrane at 90-100 degrees C and 0% relative humidity. The proton conductivity of the PTF series could be improved by sulfonation with sulfuric acid and could be maintained after blending with polyurethane. Pure methanol could be used as a fuel source because of the insolubility and nonwetting properties of PTF in methanol to increase the output current density for a PTF membrane electrode assembly. (C) 2007 Wiley Periodicals, Inc.
Synthesis and Characterization of Poly(n-undecyl isocyanate)/Polyaniline Polyblend
(2010-07-05)
Li, Yu-Jen
;
Ho, Ko-Shan
;
Lo, Wan-Ting
;
Yang, Shin-Shiao
;
Chao, Liang
Poly(n-undecyl isocyanate) (PUDIC)/n-dodecylbenzenesulfonic acid (DBSA)-doped polyaniline (PANIDBSA) polyblend was prepared and the effect of the H-bonding between these two polymers on the compatibility, conjugation chain length of PANIDBSA, and helixity of PUDIC in the polyblend system were studied. The monomer and polymer were characterized by NMR spectra and the polyblend was analyzed by FTIR, UV-vis spectra, and wide-angle X-ray diffraction. It was found when the blend composition of the PUDIC was higher than 10%, the WAXD patterns demonstrated lower angle shifting for the peaks at around 2 theta = 2-2.5 degrees, referring to the distance between the layers of the layered structure of PANIDBSA crystalline with increasing PUDIC, indicating the expansion of the layered structure of PANIDBSA. The FTIR spectra illustrated the presence of an absorption peak at 1700 cm(-1) shift to higher wave number with PUDIC due to its H-bonding with PANIDBSA. The UV-vis spectra of PANIDBSA described a blue-shift of the lambda(max) with PUDIC, indicating that the presence of PUDIC in the polyblend system can interrupt and decrease the conjugation chain length of PANIDBSA. The optical activity of the helical PUDIC decreased notably with the presence of PANIDBSA, resulting from the reversed helical effect (de-nature) of H-bonding. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1-7, 2010