Polymerizations selective

The breadth of reactions catalyzed by cobalt compounds is large. Some types of reactions are hydrotreating petroleum (qv), hydrogenation, dehydrogenation, hydrodenitrification, hydrodesulfurization, selective oxidations, ammonoxidations, complete oxidations, hydroformylations, polymerizations, selective decompositions, ammonia (qv) synthesis, and fluorocarbon synthesis (see Fluorine compounds, organic). 

H. Schulz, K. Beck, E. Erich. 1988. Fischer-Tropsch CO-hydrogenation, a non trivial surface polymerization Selectivity of branching. In Proceedings of the 9th International Congress on Catalysis, Calgary, Vol. 2, p. 829. 

Synthetic applications of carbon radical additions to allenes cover aspects of polymerization, selective 1 1 adduct formation and homolytic substitutions. If heated in the presence of, e.g., di-tert-butyl peroxide (DTBP), homopolymerization of phenylal-lene is observed to provide products with an average molecular weight of 2000 (not shown) [58]. IR and 1H NMR spectroscopic analyses of such macromolecules point to the preferential carbon radical addition to CY and hence selective polymerization across the 2,3-double bond of the cumulene. Since one of the olefinic jr-bonds from the monomer is retained, the polymer consists of styrene-like subunits and may be... 

Starting from those two dispersion situations, the locus of initiation is expected to have a great influence on the reaction products and the quality of the obtained copolymers. Therefore three different initiators were used, an oil-soluble initiator (e.g., 2,2 azobis(2,4-dimethylvaleronitrile (ADVN)), an interfacial active initiator (e.g., PEGA200), and a water-soluble initiator (e.g., potassium peroxodisulfate (KPS)) in order to initiate the polymerization selectively in one of the phases or at the interface. 

An important aspect of polymerization is the ability to obtain different products from the same monomer by proper choice of catalyst and reaction conditions. These products may differ in stereochemical configuration or in the nature of the repeating unit. For example, it has been possible to polymerize selectively one or all of the functional groups of polyfunctional monomers. A subject of particular fascination has been... 

Strikovsky AG, Kasper D, Grun M, Green BS, Hradil J, Wulff G (2000) Catalytic molecularly imprinted polymers using conventional bulk polymerization or suspension polymerization Selective hydrolysis of diphenyl carbonate and diphenyl carbamate. J Am Chem Soc 122 6295... 

Se et al. presented the synthesis of poly[(VS- -I)-b-S] block—graft copolymers.157 The backbone, a diblock copolymer of 4-(vinyldimethylsilyl)styrene (VS) and styrene, was prepared first by anionic polymerization. The VS monomer was polymerized selectively through the styryl double bond at low... 

Coordination polymerization of dienes has progressed significantly within the last decade. Selective polymerization of 1,3-dienes is reinforced by conventional transition metal catalysts and by new organolanthanide catalysts. Nonconjugated dienes also polymerize selectively to produce polymers with cyclic units or vinyl pendant groups. Living polymerization of dienes has become common, which enabled preparation of block copolymers of dienes with alkenes and other monomers. Another new topic in this field is the polymerization of allenes and methylenecycloalkanes catalyzed by late transition metal complexes. These reactive dienes and derivatives provide polymers with novel structure as well as functionalized polymers. The precision polymerization of 1,2-, 1,3-, and l,n-dienes, achieved in recent years, will be developed to construct new polymer materials with olefin functionality. 

This study revealed that under microwave conditions polymerization phenomena such as polymerization selectivity, polymerization temperature shift, and polymerization temperature shift as a result of the microwave power setting, can be observed when products are compared with those obtained under conventional conditions. To explain these phenomena it was proposed that a new dipole partition function is present in the microwave field, so values of thermodynamic properties such as internal energy and Gibbs free energy of materials with permanent dipole moments change under microwave conditions, which in turn leads to shifts in the reaction equilibrium and kinetics compared with conventional conditions at the same temperature [46]. 

You are asked to select a suitable radical initiator for a polymerization process to be carried out at 50°C and which needs to be completed within 8 h. By considering that the initiator concentration must not fall below half its original value during the polymerization, select the most appropriate initiator from the list below. 

Uses Curing agent for epoxy resins solvent for extraction of benzene, toluene, other aromatic hydrocarbons from oil refinery streams cosolvent in Sulfinol gas desulfurization process aprotic process solvent (chem. synthesis) solvent in surf, coatings, pharmaceuticals, polymerization selective solvent separation of low boiling alcohols, mineral oils, tars plasticizer dielec, in elec, equipment component in hydraulic fluids medicine (antibacterial) adjuvant in prod, of polyatylsulfone resins for food pkg. 

For monomers with both terminal and internal triple bonds (RC -C6H4-C H), all catalysts used exhibited high degree of polymerization selectivity in favour of terminal ... 

The versatility of chain transfer polymerization together with its easiness of use relative to the synthetic effort that would require a one catalyst, one material approach or to the difficulties encountered by other routes explored for fine-tuning polymerization selectivities makes this approach undoubtedly an attractive and promising field for the future of coordination polymerization. CCTP renders the emergence of the one catalyst, several materials paradigm a reality. 

The study performed revealed some polymerization phenomena such as polymerization selectivity, polymerization... 

Electrospinning has the advantages of easiness, efficiency, low cost, high yield, and high degree of reproducibility of the obtained materials. Due to its inherent adaptability and applicability, the electrospinning technique can be applied to the preparation of different components for oil spill cleaning, from nonpolar polymeric absorbents to nonpolar and polar polymeric selective filtration membranes [40 4]. 

Branched polymers (family 3 Direct polymerization) Selective esterification to control branching control of molecular weight and properties TBD... 

---