報告題目：聚乙胺自組裝超分子結(jié)晶與納米分級及手性無機材料
報告人：金仁華教授 Kanagawa University
報告時間：2013年9月17日上午10:00
報告地點：芙蘭學術(shù)中心A403
主持人；陳永明教授
報告內(nèi)容簡介：
In nature, biosilica such as diatoms and sponges have special silica mineralization process, in which organic matrices such as polypeptides (silafines), proteins (silicateins) and long chain polyamines play an important role as catalytic templates to direct the silica deposition. Although the details mechanism of the silica growth towards precisely ordered geometrical structures is not clear yet, rationalization of the silica deposition by association of long chain polyamines with suitable acidic components is a desirable for control the silica based materials. From this viewpoint, we specially focused our attentions to a simple polymer with secondary amine in the main chain, that is polyethyleneimine (-CH2CH2NH-). The most interesting feature of the polyethyleneimine (PEI) is its crystallizability in aqueous media. Especially, PEI can form nano size-based crystalline entities which are capable of catalyzing the hydrolytic polycondensation of alkoxysilane on the surface of crystalline entities with keeping the entities’ morphologies.
In our approach to nanostructured silica, we firstly promoted the crystallization of PEI by addition of a series of additives in water, which results in crystalline entities with definite shapes. And then, only by mixing the PEI entities obtained with tetramethoxysilane or titanium salts at room temperature in aqueous media, we synthesized exclusively controlled silica and titania nanomaterials with definite morphologies such as fibril-, ribbon-, sheet-, tube-based hierarchical objects.
On the other hand, in the strategy for chirality-controlled silica nanomaterials, we subtly prepared the chiral supramolecular crystalline entities consisted of achiral PEI and chiral tartaric acid (D- and L-forms) and then used the chiral entities as templates in hydrolytic polycondensation of tetramethoxysilane. This two steps route efficiently produces nanofiber-based chiral silica. The pure chiral silica after calcined at 900oC remained its chiral activity. The D-form silica and L-form silica, which are based respectively the chiral source of D-tartrate and L-tartrate, just are mirror relation in their solid state CD spectra. When organic molecules or inorganic components physically associated or chemically bonded to the chiral silica, the guests become CD active showing induced CD signals in their absorption range.
簡歷：
Dr. Ren-Hua Jin graduated from Jilin University (Changchun, China) in 1982 and got his PhD from Nankai University (Tianjin, China) in 1987. After that, he joined Beijing University of Chemical Technology as an assistant professor for 2 years and transferred to the University of Tokyo as a postdoctoral fellow where he worked with Prof. Shyohei Inoue and Prof. Takuzo Aida and completed the first synthesis of a porphyrin centered dendrimer. He worked at Miyazaki University as an associate professor from 1994 to 1997. Then, he worked in Kawamura Institute of Chemical Research as a leader and director for 14 years before joining present place of Kanagawa University as a full professor. Dr. Jin''''''''s major research contributions span over a wide variety of topics in polymer science and materials chemistry. His early work concerned mainly with architecture and synthesis of functional polymers and their behaviors of self-assembly in aqueous media. Later, he expanded his polymeric topics to the fields of hybrid nanomaterials and their applications with nature inspired approaches. His current research interest lies in supramolecular chemistry, nanomaterials with shape- and chirality-control and their applications in the catalysis, energy-conversion, wettability control, sensing etc. He was awarded the Chinese Chemical Society Young Chemist Award in 1988 for his achievement in the study on chiral polymers and racemic resolution.