Synthesis and Frictional Properties of Poly(2,3-dihydroxypropyl methacrylate) Brush Prepared by Surface-initiated Atom Transfer Radical Polymerization
作者:Motoyasu Kobayashi、Atsushi Takahara
DOI:10.1246/cl.2005.1582
日期:2005.12
Surface-initiated atom transfer radical polymerization (ATRP) of (2,2-dimethyl-1,3-dioxolan-4-yl)methyl methacrylate (1) was carried out from an immobilized initiator on a silicon wafer to result in a high-density polymer brush, which was converted to the hydrophilic polymer brush consisting of 2,3-dihyroxypropyl methacrylate (2) units, successively. The poly(2) brush showed low dynamic friction coefficient in water.
SILICON COMPOUND AND METHOD FOR PRODUCING SAME, AND USE THEREOF
申请人:TOYO TIRE & RUBBER CO., LTD.
公开号:US20150038643A1
公开(公告)日:2015-02-05
A novel silicon compound capable of initiating radical polymerization is provided. The silicon compound is represented by the following general formula (1)
A-Z
1
—S—Z
2
—Si(OR
1
)
n
(R
2
)
3-n
(1)
wherein A is a group capable of initiating radical polymerization, Z
1
and Z
2
are each independently a bivalent group that has at least a carbon atom, R
1
and R
2
are each independently an alkyl group having from 1 to 3 carbon atoms, and n is an integer of 1 to 3. A radical polymerization initiator comprising the silicon compound, and a polymer obtained by radical polymerization of a monomer with the radical polymerization initiator are also provided. Also provided is a complex having a polymer graft chain formed on a solid substance surface with the use of the silicon compound.
Divergent Construction of Heterocycles by SOMOphilic Isocyanide Insertion under N-Heterocyclic Carbene Catalysis
作者:Qianrong Li、Cong-Ying Zhou、Chengming Wang
DOI:10.1021/acs.orglett.2c03148
日期:2022.10.21
substitution-type radical cyclization in the absence of any light, transition metals, and external oxidants. The aldehyde-free, scalable, and operationally simple protocol tolerates diverse functionalized biaryl isonitriles and activated α-halides. Moreover, it can be further applied to the divergent construction of other N-heterocycles. Preliminary mechanistic studies disclose that an NHC-derived radical cation
Redox-Neutral Generation of Iminyl Radicals by <i>N</i>-Heterocyclic Carbene Catalysis: Rapid Access to Phenanthridines from Vinyl Azides
作者:Lixia Liu、Qijing Zhang、Chengming Wang
DOI:10.1021/acs.orglett.2c02118
日期:2022.8.19
carbene-catalyzed oxidant-, metal- and light-free iminyl radical generation pathway stemming from the reaction of vinyl azide and α-bromo ester is uncovered. This newly developed methodology is successfully applied to the redox-neutral construction of a number of diversified phenanthridine derivatives with nice functional group compatibility. Insights from the mechanism study reveal that this NHC-catalyzed transformation
揭示了源自乙烯基叠氮化物和 α-溴酯反应的N-杂环卡宾催化的氧化剂、金属和无光亚胺基自由基生成途径。这种新开发的方法成功地应用于具有良好官能团相容性的多种菲啶衍生物的氧化还原中性构建。机理研究表明,这种 NHC 催化的转化可能通过烷基自由基加成引发的 HAS 过程进行,亚胺自由基作为活性中间体。
Synthesis of Monodisperse Silica Particles Coated with Well-Defined, High-Density Polymer Brushes by Surface-Initiated Atom Transfer Radical Polymerization
Monodisperse silica particles (SiPs) of diameter between 100 and 1500 nm were surface-modified in a mixture of ethanol/water/ammonia with a newly designed triethoxysilane having an atom transfer radical polymerization (ATRP) initiating site, (2-bromo-2-methyl)propionyloxyhexyltriethoxysilane. The surface-initiated ATRP of methyl methacrylate (MMA) mediated by a copper complex was carried out with the initiator-fixed SiPs in the presence of a "sacrificial" (free) initiator. The polymerization proceeded in a living manner in all examined cases, producing SiPs coated with well-defined PMMA of a target molecular weight up to 480K with a graft density as high as 0.65 chains/nm(2). These hybrid particles had an exceptionally good dispersibility in organic solvents. Transmission electron microscopic and atomic force microscopic observations of their monolayers prepared at the air-water interface revealed that they formed an ordered 2-dimensional lattice extending throughout the monolayer.