نتایج جستجو برای: polymeric catalyst

تعداد نتایج: 67474  

Journal: :Molecules 2016
Shuang Ma Patrick H Toy

The study of N-heterocyclic carbenes (NHCs) as organocatalysts has proliferated in recent years, and they have been found to be useful in a variety of reactions. In an attempt to further expand their utility and to study their recyclability, we designed and synthesized a series of self-supported NHCs in which the catalytic carbene groups form part of a densely functionalized polymer backbone, a...

Journal: :Journal of the Royal Society, Interface 2007
A S Jones J D Rule J S Moore N R Sottos S R White

Self-healing polymers, based on microencapsulated dicyclopentadiene and Grubbs' catalyst embedded in the polymer matrix, are capable of responding to propagating fatigue cracks by autonomic processes that lead to higher endurance limits and life extension, or even the complete arrest of the crack growth. The amount of fatigue-life extension depends on the relative magnitude of the mechanical ki...

Journal: :The journal of physical chemistry. B 2006
Hanjing Tian Elizabeth I Ross Israel E Wachs

A quantitative method based on UV-vis diffuse reflectance spectroscopy (DRS) was developed that allows determination of the fraction of monomeric and polymeric VO(x) species that are present in vanadate materials. This new quantitative method allows determination of the distribution of monomeric and polymeric surface VO(x) species present in dehydrated supported V(2)O(5)/SiO(2), V(2)O(5)/Al(2)O...

2011
Irene Chou Chen Olga Kuksenok Victor V. Yashin Ryan M. Moslin Anna C. Balazs Krystyn J. Van Vliet

Polymeric hydrogels that exhibit autonomous, coupled chemical and mechanical oscillations are a unique example of synthetic, active soft matter. Here, we explore the effects of gel aspect ratio and absolute dimensions on pattern formation in hydrogels undergoing the Belousov-Zhabotinsky (BZ) reaction. We synthesize and analyze N-isopropylacrylamide gels containing covalently bound BZ catalyst a...

2009
Z. Páal R. Schlögl

Results of electron spectroscopy (XPS and UPS) of platinum black catalyst measured in various states of the catalyst have been summarized. XPS showed up to almost 50% carbon and up to 20% oxygen on a sample stored in air. These, however, had almost no influence on the chemical state of Pt, except for the appearance of minor surface oxide. A Pt purity of ~90% could be reached by regeneration wit...

2009
Laurent Plasseraud Hélène Cattey Philippe Richard

The title compound has been isolated as single crystals from the synthesis of propylene carbonate from racemic 1,2-propanediol and carbon dioxide using n-Bu2SnO as a catalyst precursor. The X-ray crystallographic structure analysis revealed the self-assembly of di-n-butyltin(IV) 1,2-propanediolate units, linked together through long-distance Sn–O interactions leading to a one-dimensional polyme...

Journal: :Chemical communications 2016
Chengcheng Tian Xiang Zhu Carter W Abney Ziqi Tian De-En Jiang Kee Sung Han Shannon M Mahurin Nancy M Washton Sheng Dai

The design and synthesis of metal-free heterogeneous catalysts for efficient hydrogenation remains a great challenge. Here we report a novel approach to create conjugated nanoporous polymers with efficient hydrogenation activities toward unsaturated ketones by leveraging the innate steric encumbrance. The steric bulk of the framework as well as the local sterics of the Lewis basic sites within ...

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