It is generally accepted that a new material is often developed by ?nding a new synthesis method of reaction or a new reaction catalyst. Historically, a typical example may be referred to as a Ziegler–Natta catalyst, which has allowed large-scale production of petroleum-based polyole?ns since the middle of the 20th century. New polymer synthesis, therefore, will hopefully lead to creation of new polymer materials in the 21st century. This special issue contributed by three groups focuses on recent advances in polymer synthesis methods, which handle the cutting-edge aspects of the advanced technology. The ?rst article by Yokozawa and coworkers contains an overview of the - action control in various condensation polymerizations (polycondensations). Advanced technologies enabled the control of stereochemistry (regio-, g- metrical-, and enantio-selections), chemoselectivity, chain topology, and st- chiometry of monomers, giving a high molecular weight polymer. It has been recognized for a long time, however, that polycondensation is a dif?cult p- cess in controlling the reaction pathway, because the reaction is of step-growth and the reactivity of monomers, oligomers, and polymers are almost the same during the reaction and hence, the molecular weight of polymers and its d- tribution (M /M ) are impossible to regulate. The authors’ group developed w n a new reaction system (chain-growth condensation polymerization), changing the nature of polycondensation from step-growth to chain-growth; namely the propagating chain-end is active, allowing for control of the product molecular weight as well as the distribution.
Timberlake claimed in 1980 that a fundamental problem with Singer's work is the lack of an adequate definition of suffering ...
3. D. Layne. 2013. Tree Fruit: Protecting Your Investment. American/Western Fruit Grower, September/October. 4. R. Snyder and J. Melu-Abreu. 2005. Frost ...
At that time, these were in the low $10s of millions. ... be a good partner going forward, even though it takes longer to get the deal done," offered Chess.
[ 59 ] S. Kotz , T. J. Kozubowski , and K. Podgorski , The Laplace ... valued signal processing : The proper way to deal with impropriety , ” IEEE Trans .
Some documents are annotated; some are left without annotations to provide more flexibility for instructors. This booklet can be packaged at no additional cost with any Longman title in technical communication.
Chemistry: An Introduction to General, Organic, and Biological Chemistry; Chemistry Study Pack Version 2.0 CD-ROM; The Chemistry of Life CD-ROM;...
The emission rates for ammonia (Casey et al., 2006): • Layers: 116 g NH3 per AU (AU or animal unit or 500 kg). • Broilers: 135 g NH3 per AU (AU or animal unit or 500 kg). Emission rates in different reports vary from less than either 10 ...
[45] B.F. Hoskins, R. Robson, “Design and construction of a new class of scaffolding-like materials comprising infinite polymeric frameworks of 3D-linked molecular rods. A reappraisal of the zinc cyanide and cadmium cyanide structures ...
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