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2 results on '"Yaping Huang"'

1. Petunia-shaped superstructures of CaCO3 aggregates modulated by modified chitosan

Author

Po Liang, Yaping Huang, Ingo Lieberwirth, Yong Zhou, Hao Wei, Qiang Shen, Dujin Wang, Ying Zhao, and Duanfu Xu

Subjects
chemistry.chemical_element, Nanotechnology, Calcium, law.invention, Calcium Carbonate, chemistry.chemical_compound, law, Electrochemistry, Molecule, General Materials Science, Carboxylate, Crystallization, Particle Size, Spectroscopy, chemistry.chemical_classification, Chitosan, Aqueous solution, Chemistry, Air, Water, Surfaces and Interfaces, Polymer, Condensed Matter Physics, Solutions, Calcium carbonate, Chemical engineering, Superstructure (condensed matter)
Abstract

This paper presents the crystallization behavior of calcium carbonate at the air/liquid interface of aqueous systems of carboxymethyl chitosan (CMCS) using the Kitano method. Although the synthesized CMCS (Mw approximately 100,000) with 1.57 degree of carboxymethyl substitution shows no surface activity, it controls the crystallization of calcium carbonate to form a petunia-shaped superstructure. The shuttlecock-like head of this superstructure strongly supports Colfen's opinion (Rudloff, J.; Colfen, H. Langmuir 2004, 20, 991-996) for the existence of a gas template of CO2 bubbles temporarily captured by polymer molecules, while formation of the stem of this superstructure is provisionally attributed to the presence of the strong electrostatic interactions between calcium ions and the carboxylate groups. The CaCO3 superstructure and its morphology depend not only on the polymer concentration but also on the combined number of calcium ions per CMCS molecule. These results imply that this simple and versatile method expands the morphological investigation of mineralization processes.

Published
2004

2. Heck Reactions Catalyzed by Ultrasmall and Uniform Pd Nanoparticles Supported on Polyaniline.

Author

Lei Yu, Yaping Huang, Zheng Wei, Yuanhua Ding, Chenliang Su, and Qing Xu

Subjects
*NANOPARTICLE synthesis, *AIR, *POLYANILINES, *ANILINE synthesis, *CATALYSTS, *HECK reaction
Abstract

Using air as the oxidant instead of the traditionally employed persulfates, the smaller and more uniform Pd nanoparticles (around 2 nm) supported on polyaniline (Pd@PANI) can be easily fabricated by the oxidation-polymerization of aniline with PdCl2. This material is an efficient and environmentally friendly catalyst for Heck reactions due to its recyclability, low loading, and ligand-free and mild reaction conditions. It was even tolerant to sulfur-containing substrates. This work reports the Pd@PANI-catalyzed Heck reactions with very wide substrate scopes, and discloses the catalytic mechanisms based on experimental findings and results of catalyst analysis and characterization. [ABSTRACT FROM AUTHOR]

Published
2015
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