Polymer, chemical physics catalytic properties

Kokorin, Alexander I, was bom in 1947. Was graduated as a biophysicist in 1970 Ph.D. (Candidate of Sciences) in 1974 D.Sc. degree (Doctor of Sciences) in physical chemistry - in 1992. At present Principal Researcher and Deputy Head of the Division of Kinetics and Catalysis, N. Semenov Institute of Chemical Physics of Russian Academy of Sciences, Moscow, Russia. Area of research interests chemical methods of solar energy conversion chemical physics of organized molecular systems, including nanosized oxide semiconductors doped with transition metal ions, and polymer-metal complexes the study of their structure, absorptive, catalytic, photocatalytic and photoelectrochemical properties. EPR spectroscopy and spin-spin interaction between paramagnetics. He is the author and co-author of more than 170 publications, including two books and several reviews and book chapters. 

The results of these studies and others reported previously demonstrate that the 1-oxypyridinyl group is an effective catalyst for the transacylation reactions of derivatives of carboxylic and phosphoric acids when incorporated in small molecules and polymers. Furthermore, this catalytic site exhibits high selectivity for acid chlorides in the presence of acid anhydrides, amides, and esters. Therefore, catalysts bearing this group as the catalytic site can be used successfully in synthetic applications that require such specificity. The results of this work suggest that functionalized polysiloxanes should be excellent candidates as catalysts for a wide variety of chemical reactions, because they combine the unique collection of chemical, physical, and dynamic-mechanical properties of siloxanes with the chemical properties of the functional group. Finally, functionalized siloxanes appear to mimic effectively enzyme-lipophilic substrate associations that contribute to the widely acknowledged selectivity and efficiency observed in enzymic catalysis. 

The incorporation of homogenous Ti(lV)/trialkanolamine catalyst in polymeric membranes has been investigated as heterogeneous catalysts for the selective oxidation of secondary amines to nitrones by alkyl hydroperoxides (Buonomeima et al., 2004, 2006). Three polymers, PVDF, a modified polyetherketone (PEEK-WC), and polyacrUo-nitrile (PAN) with different functional groups and chemical-physical properties were used to tune the reactivity of the catalytic polymeric membranes. 

The rate of drug release (E) from the eroding matrix is controlled by (a) the chemical properties of the system - the hydrolytic and the neutralizing process at the boundary of the device, catalytic degradation of the polymer and the intrinsic backbone reactivity, and (b) several concomitant physical processes such as water diffusivity, water solubility, water partitioning, etc. 

The introduction of functional groups is suitable to control the chemical and physical properties of the polymer. However, the introduction of functional groups may cause a reaction of the unshared electron pairs of the functional groups with the active catalytic sites. Thus, the active sites of the catalyst are destroyed. In order to overcome this problem, a procedure has been developed, where the functionalized monomers, such as maleic acid, nadic acid or their anhydrides are grafted after the polymerization reaction (4,37). Grafting takes place as a radical reaction, using e.g., dicumyl peroxide. Other attempts use excessive amounts of catalysts. 

There are an increasing number of reports of useful, specific chemical and physical properties in MOPs. Recent examples include high gas separation efficiencies in PIM membranes [41, 78], catalytically-active phthalocyanine and porphyrin network polymers [52], and HCPs with elevated isosteric heats of sorption for CH [39], Many more possibilities for exploration exist - the following list suggests just a few such opportunities ... 

The molecular weight and molecular weight distribution of polymers affects the volume fraction of chain ends and hence the free volnme of the polymer and, consequently, determines the chain mobility and crystallisation. It also determines the number of acidic end gronps that can participate in hydrolysis and their possible catalytic effect. Overall, the molecular weight affects both the chemical and physical properties of a polymer." ... 

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