Browsing by Author "Sheu, HS"

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Preparation and supramolecular self-assembly of a polypeptide-block-polypseudorotaxane
(2005-07-26)
Lee, HF
;
Sheu, HS
;
Jeng, US
;
Huang, CF
;
Chang, FC
We have successfully prepared a new class of self-assembled biomaterial: a polypeptide-block-polypseudorotaxane diblock copolymer. This diblock copolymer is comprised of an a-helical polypeptide rod, based on gamma-benzyl-L-glutamate, and an originally coiled segment P(EO19-r-PO3); it forms inclusion complexes with a-cyclodextrins (alpha-CDs) to give crystalline polypseudorotaxanes. Formation of the polypseudorotaxane converts the conformation of P(EO19-r-PO3) from a flexible chain into a rodlike structure, which results in a novel block copolymer exhibiting a rod-rod conformation. Intrinsic interactions (e.g., the polypseudorotaxane's channel-type crystallization, the polypeptide's secondary structure, and microphase separation) within and between these rod-rod diblock copolymers contribute to their hierarchical self-assembly behavior, which we characterized using DSC, H-1 NMR spectroscopy, C-13 CP/MAS NMR spectroscopy, WAXS, and SAXS. The data obtained from the WAXS and SAXS studies clearly indicate the formation of juxtaposed bilayer-like nanostructure featuring hexagonally packed PBLG stacks and channel-type polypseudorotaxane moieties.
The formation of perovskite PbTiO3 powders by sol-gel process
(2006-06-10)
Lee, CY
;
Tai, NH
;
Sheu, HS
;
Chiu, HT
;
Hsieh, SH
Nano-sized cubic Pb2Ti2O6 and monoclinic PbTi3O7 were obtained as the first stage products, by sol-gel process using anhydrous lead acetate and titanium(IV) isopropoxide as precursors; then, as the powder was heated, Pb2Ti2O6 gradually transformed to perovskite PbTiO3 around 673 K. (c) 2005 Elsevier B.V. All rights reserved.