The climates of Asia are affected significantly by the extent and height of the Himalayan mountains and the Tibetan plateau1,2,3,4 Uplift of this region began about 50 Myr ago, and further significant increases in altitude of the Tibetan plateau are thought to have occurred about 10–8 Myr ago4,5, or more recently However, the climatic consequences of this uplift remain unclear Here we use records of aeolian sediments from China6,7 and marine sediments from the Indian8,9,10 and North Pacific oceans11 to identify three stages of evolution of Asian climates: first, enhanced aridity in the Asian interior and onset of the Indian and east Asian monsoons, about 9–8 Myr ago; next, continued intensification of the east Asian summer and winter monsoons, together with increased dust transport to the North Pacific Ocean11, about 36–26 Myr ago; and last, increased variability and possible weakening of the Indian and east Asian summer monsoons and continued strengthening of the east Asian winter monsoon since about 26 Myr ago The results of a numerical climate-model experiment, using idealized stepwise increases of mountain–plateau elevation, support the argument that the stages in evolution of Asian monsoons are linked to phases of Himalaya–Tibetan plateau uplift and to Northern Hemisphere glaciation

Evolution of Asian monsoons and phased uplift of the Himalaya–Tibetan plateau since Late Miocene times

The utilization of plant oil renewable resources as raw materials for monomers and polymers is discussed and reviewed. In an age of increasing oil prices, global warming and other environmental problems (e.g. waste) the change from fossil feedstock to renewable resources can considerably contribute to a sustainable development in the future. Especially plant derived fats and oils bear a large potential for the substitution of currently used petrochemicals, since monomers, fine chemicals and polymers can be derived from these resources in a straightforward fashion. The synthesis of monomers as well as polymers from plant fats and oils has already found some industrial application and recent developments in this field offer promising new opportunities, as is shown within this contribution. (138 references.)

/pdf/plant-oil-renewable-resources-as-green-alternatives-in-4xxr5ig1d1.pdf

Plant oil renewable resources as green alternatives in polymer science

Living polymerization techniques can be used to achieve a high degree of control over polymer chain architecture. Examples of the type of polymers that can be synthesized include block copolymers, comb-shaped polymers, multiarmed polymers, ladder polymers, and cyclic polymers. This control of structure, in turn, results in polymers with widely diverse physical properties, even though they are made from readily available low-cost monomers.

https://science.sciencemag.org/content/sci/251/4996/887.full.pdf

Living Polymerization Methods

numerous polyethylene or polypropylene compounds have been synthesized by metal-catalyzed coordination-insertion polymerization. On the other hand, organometallic catalysts * To whom correspondence should be addressed. E-mail: nozaki@chembio.t.utokyo.ac.jp. Akifumi Nakamura (left) was born in 1984 in Kanagawa, Japan. He received his B.S. degree in 2007 and M.S. degree in 2009 from the University of Tokyo under the guidance of Professor Kyoko Nozaki. During that time he joined Professor Keiji Morokuma’s group at Kyoto University as a visiting student. In 2009, he started his Ph.D. study at the University of Tokyo under the guidance of Professor Kyoko Nozaki. He is also a research fellow of the Japan Society for the Promotion of Science. His research interests include synthetic organic chemistry, organometallic chemistry, computational chemistry, and polymer chemistry.

Coordination−Insertion Copolymerization of Fundamental Polar Monomers

1.3. Scope of Review 5161 2. Methacrylate Polymerization 5161 2.1. Lanthanide Complexes 5161 2.1.1. Nonbridged Lanthanocenes 5161 2.1.2. ansa-Lanthanocenes 5164 2.1.3. Half-Lanthanocenes 5166 2.1.4. Non-lanthanocenes 5166 2.2. Group 4 Metallocenes 5170 2.2.1. Nonbridged Catalysts 5170 2.2.2. ansa-C2v-Ligated Catalysts 5173 2.2.3. ansa-C2-Ligated Catalysts 5173 2.2.4. ansa-C1-Ligated Catalysts 5176 2.2.5. ansa-Cs-Ligated Catalysts 5177 2.2.6. Constrained Geometry Catalysts 5178 2.2.7. Half-Metallocene Catalysts 5180 2.2.8. Supported Catalysts 5180 2.3. Other Metallocene Catalysts 5180 2.4. Nonmetallocene Catalysts 5181 2.4.1. Group 1 and 2 Catalysts 5181 2.4.2. Group 13 Catalysts 5183 2.4.3. Group 14 Catalysts 5186 2.4.4. Transition-Metal Catalysts 5187 3. Acrylate Polymerization 5188 3.1. Lanthanocenes 5188 3.2. Group 4 Metallocenes 5189 3.3. Nonmetallocenes 5190 4. Acrylamide and Methacrylamide Polymerization 5191 4.1. Acrylamides 5191 4.2. Methacrylamides 5192 4.3. Asymmetric Polymerization 5193 5. Acrylonitrile and Vinyl Ketone Polymerization 5196 5.1. Acrylonitrile 5196 5.2. Vinyl Ketones 5196 6. Copolymerization 5197 6.1. Polar-Nonpolar Block Copolymers 5197 6.2. Polar-Nonpolar Random Copolymers 5199 6.3. Polar-Polar Copolymers 5204 7. Ion-Pairing Polymerization 5206 8. Summary and Outlook 5208 9. Acknowledgments 5208 10. References 5208

Coordination polymerization of polar vinyl monomers by single-site metal catalysts.

Polymerisation vivante de methacrylates en presence de cetene silyl acetals comme amorceurs et fluorure, bifluorure, cyanure ou azide comme catalyseurs

Group transfer polymerization - polymerization of acrylic monomers

L'incorporation de liaisons «tete a tete» dans une chaine de PMMA reduit la temperature de degradation en facilitant la rupture homolytique de la chaine. Lorsque le degre de polymerisation du polymere est superieur a 200, cet effet est reduit par la recombinaison de cage

Gordon M. Cohen

Papers

Group transfer polymerization - polymerization of acrylic monomers

Thermal degradation of poly(methyl methacrylate). 3. Polymer with head-to-head linkages