Search

Your search keyword '"Chan, H.S.O."' showing total 81 results
Start Over Author "Chan, H.S.O."
81 results on '"Chan, H.S.O."'

2. Unusual ionic behavior in microemulsion-polymerized membranes

Author

Ong, C.L., Gan, L.M., Ong, C.K., Chan, H.S.O., and Xu, G.

Subjects
Chemical research -- Analysis, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

Experiments on bicontinuous microemulsion membranes found large ions had higher mobility due to the effect of cation hydration shells on the less heavy ions making them larger.

Published
1999

3. A new water-soluble, self-doping conducting polyaniline from poly(o-aminobenzylphosphonic acid) and its sodium salts: synthesis and characterization

Author

Chan, H.S.O., Ho, P.K.H., Ng, S.C., Tan, B.T.G., and Tan, K.L.

Subjects
Aniline -- Research, Polymers -- Analysis, Electric properties of materials -- Research, Chemistry
Abstract

A novel conducting polyaniline has been synthesized by persulfate oxidative coupling of o-aminobenzylphosphonic acid and its sodium salt in an acidic medium. A polymer is obtained in the 43% self-doping emeraldine state os oxidation with internal proton transfer from the phosphonic acid functions to the nitrogen bases. Steric effects and charge-pinning in the hydrogen-bonded zwitterions are indicated.

Published
1995

4. Resonant optical nonlinearity of fullerenes in free-standing polymethyl methacrylate films

Author

Ji, W., Tang, S.H., Xu, G.Q., Chan, H.S.O., Ng, S.C., and Ng, W.W.

Subjects
Polymethylmethacrylate -- Research, Carbon allotropes -- Analysis, Physics
Abstract

Polymethyl methacrylate films which are embedded with fullerenes are synthesized. The third-order nonlinear optical susceptibility of the films is obtained by the use of degenerate four-wave integration experiments and transmission measurements using nanosecond laser pulses of 608 nanometer wavelength. The transmission measurements are influenced by irradiance. Optical susceptibility is found to be 10(super -10) electrostatic units.

Published
1993

11. Surface phase transition of Cu/Si(111)-(5×5) by scanning tunnelling microscopy and photoemission study

Author

Zhang, Y.P., Yong, K.S., Chan, H.S.O., Xu, G.Q., Gao, X.Y., Qi, D.C., Wang, X.S., Wee, A.T.S., Zhang, Y.P., Yong, K.S., Chan, H.S.O., Xu, G.Q., Gao, X.Y., Qi, D.C., Wang, X.S., and Wee, A.T.S.

Abstract

The phase transition process from the Si(1 1 1)-(7 × 7) surface to the Cu/Si(1 1 1)-(5 × 5) surface structure has been studied by scanning tunnelling microscopy and synchrotron radiation photoemission spectroscopy. The nucleation and growth of Cu/Si(1 1 1)-(5 × 5) on the Si(1 1 1)-(7 × 7) surface progress gradually with the increase in Cu coverage. Cu deposition on the Si(1 1 1)-(7 × 7) surface at room temperature may only involve the saturation of the surface dangling bonds, whereas a new surface phase of Cu/Si(1 1 1)-(5 × 5) is formed upon annealing, which saturates at a Cu coverage of 0.9 ML. Our experiments clearly show the surface phase transition process of the (5 × 5) structure as a function of the Cu coverage and provide useful insight into the Cu/Si(1 1 1)-(5 × 5) structure.

Published
2008

43. Polymers synthesized from (3-alkylthio)thiophenes by the FeCl3 oxidation method

Author

Xu, J.M., Chan, H.S.O., Ng, S.C., and Chung, T.S.

Subjects
*POLYMERS, *THIOPHENES, *FERRIC chloride
Abstract

Thiophenes substituted by alkylthio (hexylthio and dodecylthio) pedant groups were polymerized using the FeCl3 oxidation method. The polymers were characterized using microanalyses, conductivity measurements, thermogravimetry (TG) and 1H NMR, UV-Vis, FTIR and XPS. The polymers are regiorandom in structure as expected and have a head-to-tail (HT) content of about 80% based on the 1H NMR spectrum. Poly[(3-hexylthio)thiophenes] (PHTT), which carries the shorter side chain, exhibits a higher solubility in common organic solvents and is more thermally stable than the polymers with the longer dodecylthio poly[(3-dodecylthio)thiophenes] (PDDTT) chains. The polymers are moderately conductive after being doped by FeCl3 or I2. The high concentration of covalently bonded chlorine found from XPS and microanalysis and supported by 1H NMR spectra suggests chlorination of the backbone occurred during the polymerization process. The influence of chlorination on the absorption spectra and conductivity were noted and discussed. [Copyright &y& Elsevier]

Published
2002
Full Text
View/download PDF

49. Optical properties, spectral narrowing of photoluminescence and blue electroluminescence of poly(phenylene pyridine) derivatives.

Author

Fujii, A., Ootake, R., Fujisawa, T., Ozaki, M., Ohmori, Y., Laga, Tong, Yoshino, K., Lu, H.-F., Chan, H. S. O., Chan, H.S.O., and Ng, S.-C.

Subjects
POLYPHENOLS, PYRIDINE, LIGHT absorption, PHOTOLUMINESCENCE, ELECTROLUMINESCENCE
Abstract

Optical properties of poly(phenylene pyridine) derivatives, poly(2,5-dialkoxy-1,4phenylenealt-2,5-pyridine) (PHOnPY25), such as optical absorption, photoluminescence (PL), and electroluminescence (EL), have been studied. The electronic energy structures of PHOnPY25 have been determined by optical and electrochemical measurements. Strong PL with high quantum efficiency has been clarified in the films, and spectral narrowing has been observed by pulse excitation of a nitrogen laser. Intense blue EL has also been demonstrated. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results