Synthesis and characterization of graft copolymer (alginate-g-poly(N,N-dimethylacrylamide))

<正>The graft copolymerization of N,N-dimethylacrylamide onto alginate by free radical polymerization using potassium peroxymonosulphate-sarbose as a redox pair in an inert atmosphere was investigated.The reaction conditions for maximum grafting have been optimized by varying the reaction variables,including the concentration of N,N-dimethylacrylamide(7×10~(-2) mol/L to 23×10~(-2) mol/L),potassium peroxymonosulphate(2×10~(-3) mol/L to 18×10~(-3) mol/L),sarbose(0.4×10~(-3) mol/L to 3.4×10~(-3) mol/L),sulphuric acid(1×10~(-3) mol/L to 8×10~(-3) mol/L) and alginic acid(0.4 g/L to 1.8 g/L) along with time duration(60 min to 180 min) and temperature(25℃to 45℃).Water swelling capacity,metal ion sorption and flocculation studies of the synthesized graft copolymer have been performed.The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.     

Intra–intermolecular gel-free cyclopolymerization of nonconjugated diene with peroxodiphosphate/different activators redox pairs

Gel-free cyclopolymerization of N,N′-methylenebisacrylamide has been carried out using potassium peroxodiphosphate (PDP) as initiator in combination with different activators such as mercaptosuccinic acid (MSA) and thioglycollic acid (TGA) in an inert atmosphere at 45 ± 1°C and 40 ± 1°C, respectively. The rate of polymerization was found proportional to the first power of the monomer and activator concentration and the half-power of PDP in both redox systems. A mechanism involving cyclopolymerization in the propagation path has been proposed. © 1993 John Wiley & Sons, Inc.     

Ruthenium(VI)-catalysed oxidation of diols by alkaline hexacyanoferrate(III) ion. A kinetic study

The kinetics of Ru^VI-catalysed oxidation of ethane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butane-1,4-diol and 2-butoxyethanol by hexacyanoferrate(III) ion in an aqueous alkaline medium at constant ionic strength shows zeroth order dependence on hexacyanoferrate(III) and first order dependence on Ru^VI and substrate. The results suggest that a complex is formed, between Ru^VI and the diol, which slowly decomposes to a reduced form of ruthenium, which is reoxidized to Ru^VI in a fast step by alkaline hexacyanoferrate(III). A plausible reaction mechanism is proposed.     

Kinetics and mechanism of palladium(II) chloride catalysed oxidation of unsaturated acids by vanadium(V)

Summary The kinetics of the palladium(II) catalysed oxidation of acrylic, methacrylic and crotonic acid by vanadium(V), in acid medium at constant ionic strength exhibit zeroth order dependence on vanadium(V) and first order dependence on palladium(II) and the unsaturated acid. Complex formation between the palladium(II) species and the unsaturated acid, with possible exchange of chloride ion and hydrogen ion in two successive steps, was invoked. The reaction rate is determined by a rearrangement leading to elimination of chloride ion. A plausible mechanism is proposed.     

Metal–organic framework-based mixed-matrix membranes for gas separation: An overview

Mixed-matrix membranes (MMMs) have been studied widely in the field of gas separation due to their potential to overcome performance barriers found in traditional polymeric membranes. Most polymeric membranes exhibit a trade-off between permeation and selectivity, which has limited their development in many challenging separation applications. One solution to this issue utilizes the introduction of fillers into the polymer matrix to produce MMMs. Out of the many different fillers, metal–organic frameworks stand out as a promising candidate due to their highly tunable structure, molecular sieving effect, and superior compatibility with the polymer matrix. This review will provide an in-depth look into the basic mechanisms of MMMs for gas separation and different approaches to model the permeation of gases through the membrane. In addition, challenges facing the field and recent research trends for MMMs will be discussed as well as their many applications for different gas separations. Finally, some insight on the future direction for MMMs will be covered, focusing on many intriguing opportunities and challenges that must be further explored to advance this technology.