Browsing by Author "Hsiao, Chi-Hui"

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Conductive films based on sandwich structures of carbon nanotubes/silver nanowires for stretchable interconnects
(2019-06-07)
Jheng, Li-Cheng
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Hsiao, Chi-Hui
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Ko, Wen-Ching
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Hsu, Steve Lien-Chung
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Huang, Yu-Lun
A variety of conductive films made of a hybrid of two conductive nanomaterials have been used as stretchable electrodes or interconnectors, desirable for stretchable electronic devices. Their intrinsic stretchability of electrical conductivity allows for accommodating mechanical strain to a certain extent under various deformations. However, few efforts have been made to enhance the interactions between two conductive components in a hybrid system. Herein, we reported new conductive films with tri-layer sandwich structures based on carbon nanotubes (CNTs) and Ag nanowires (NWs), encapsulated in silicone rubber, exhibited high stretchability along with insignificant piezoresistivity. They are suitable to be stretchable interconnectors. A successive vacuum filtration method was used to stack the conductive components layer by layer. The effects of the stacking sequence and the interactions between layers on the stretchability and stability of the electrical properties under mechanical deformations were studied. In the case of a tri-layer conductive film comprising two CNT outer layers and one AgNW central layer in the presence of enhanced interfacial interactions, it showed exceptionally durability in withstanding repetitive deformations.
Supramolecular functionalized polybenzoxazines from azobenzene carboxylic acid/azobenzene pyridine complexes: synthesis, surface properties, and specific interactions
(2015-01-01)
Mohamed, Mohamed Gamal
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Hsiao, Chi-Hui
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Hsu, Kuo-Chih
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Lu, Fang-Hsien
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Shih, His-Kang
In this study we synthesized Azo-COOH BZ, a new benzoxazine derivative containing both azobenzene and carboxylic acid units, through the reaction of 4-(4-hydroxphenylazo) benzoic acid (Azo-COOH, itself prepared through a diazonium reaction of 4-aminobenzoic acid with phenol in the presence sodium nitrite and NaOH) with paraformaldehyde and aniline in 1,4-dioxane. Fourier transform infrared (FTIR) spectroscopy and H-1 and C-13 nuclear magnetic resonance spectroscopy confirmed the chemical structure of Azo-COOH BZ. We used differential scanning calorimetry (DSC), thermogravimetric analysis, and FTIR spectroscopy to investigate the curing behavior of this new benzoxazine monomer. DSC revealed that the exothermic peak representing the ring opening polymerization of the benzoxazine unit appeared at low temperature relative to those of typical benzoxazines, indicating the presence of the carboxylic acid and azobenzene units of this monomer catalyzing the benzoxazine ring opening reaction. In addition, blending with various molar ratios of a benzoxazine monomer presenting a pyridyl unit (Azopy BZ) led to strong intermolecular hydrogen bonding between the CO2H group of Azo-COOH BZ and the pyridyl group of Azopy BZ. These supramolecular complex systems also featured significantly lower curing temperatures (down from ca. 200 degrees C of Azo-COOH BZ to 150 degrees C of supramolecular complex), with their products retaining the high water contact angles required for low-surface-energy applications.