Browsing by Author "Wu, TL"

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Effect of incorporated CdS nanoparticles on the crystallinity and morphology of poly (styrene-b-ethylene oxide) diblock copolymers
(2005-05-15)
Yeh, SW
;
Wu, TL
;
Wei, KH
;
Sun, YS
;
Liang, KS
Surface-modified CdS nanoparticles selectively dispersed in hexagonally packed poly(ethylene oxide) (PEO) cylinders of poly(styrene-b-ethylene oxide) (PSEO) block copolymers were prepared. The photoluminescence and ultraviolet-visible characteristics of the presynthesized CdS nanoparticles in N,N-dimethylformamide and in PEO domains of the PSEO block copolymers were determined. Because of strong interactions between the CdS nanoparticles and PEO chains, as shown by Fourier transform infrared spectroscopy, the incorporation of the CdS nanoparticles prevented the PEO cylinders from properly crystallizing; this was confirmed by differential scanning calorimetry and wide-angle X-ray diffraction measurements. The intercylinder distance between the swollen and reduced-crystallinity CdS/PEO cylinders in turn increased, as confirmed by small-angle X-ray scattering and transmission electron microscopy. At a high CdS concentration (43 wt % or 8.3 vol % with respect to PEO), however, the hexagonally packed cylindrical nanostructure of the PSEO diblock copolymers was destroyed. (c) 2005 Wiley Periodicals, Inc.
Spatial position control of pre-synthesized CdS nanoclusters using a self-assembled diblock copolymer template
(2005-06-01)
Yeh, SW
;
Wu, TL
;
Wei, KH
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We report a method for fabricating ordered spatial arrangements of pre-synthesized CdS nanoparticles in thin block copolymer templates by first selectively dispersing these nanoparticles in one particular block of a diblock copolymer, in bulk, by means of dipole-dipole interactions and then using solvent selectivity to sequester CdS nanoparticles in the block copolymer thin film. A long-range, ordered morphology of US nanoclusters can be obtained by using patterned substrates with 400 nm shallow grooves. The incorporated nanoparticles retain the same luminescence characteristics as in the pure state.