Metal-containing Polymers Synthesized via Acyclic Diene Metathesis (ADMET) Polymerization Using Electrochemically-Reduced Tungsten-based Catalyst: Polycarbosilanes

Acyclic diene metathesis (ADMET) polymerization of dienes containing silicon using electrochemically produced active catalyst species (WCl₆-e⁻-Al-CH₂Cl₂) was investigated. Silicon-containing unsaturated polymers were characterized by ¹H- and ¹³C-NMR spectroscopy, gel permeation chromatography (GPC) and elemental analysis. The thermal behavior of the polymers was determined by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).     

Synthesis of Metal-containing Polymers via Ring Opening Metathesis Polymerization (ROMP). Part II: Polymers Containing Transition Metals

Following from Part I (this journal, 18(1), 2008), dedicated to main group metal containing polymers obtained by ROMP, the application of the same progressive concept to prepare polymers having this time transition metals in the side- or main-chain is here critically overviewed. These TMC polymers were produced through ROMP reactions promoted by Schrock’s Mo-carbene or the Grubbs’ Ru-carbene catalysts, the most recent and unique methodology for obtaining wished for structures. While discussing main aspects of these target-driven syntheses, as well as properties and applications of the neutral and cationic transition metal containing polymers, emphasis is laid upon organoiron macromolecules based on ferrocene scaffolds. Special attention is given to electrochemical behavior and thermal characteristics. Topics also cover polymers with other transition metals such as Co, Ni, Ru, Pd and Pt, which are important for generating zero valent metal nanoclusters in polymer films. Finally highlighted are some illustrative examples of metal-linked, metallodendrimers and hyperbranched, dendritic and star polymers.

A Highly Flexible Green Synthesis of 3,4,5-Substituted Furan-2(5H)-ones Using Nano-CdZr4(PO4)6 as Catalyst under Microwave Irradiation

A concise and efficient method for the synthesis of 3,4,5-substituted furan-2 (5H)-ones was achieved through a three-component reaction of amines, dialkyl acetylene dicarboxylate, and aromatic aldehydes using nano-CdZr₄(PO₄)₆ as catalyst under microwave irradiation. This method has several advantages such as, high efficiency, short reaction times, simple workup, and recyclability of the catalyst up to seven runs without considerable loss of activity.     

Evaluating Cu(II) Removal From Aqueous Solutions with Response Surface Methodology by Using Novel Synthesized CaCO3 Nanoparticles Prepared in a Colloidal Gas Aphron System

Removal of heavy metals from water and wastewaters has recently gained a great deal of attention due to their serious environmental problems. In this study, novel synthesized calcium carbonate nanoparticles, prepared in a colloidal gas aphron (CGA) system, were used as adsorbents for the removal of Cu²⁺ ions from aqueous solutions under different conditions. A developed pseudo-second-order (PSO) model well described the adsorption kinetics of the process. Langmuir and Freundlich adsorption isotherms have been examined and the maximum adsorption capacity from the Langmuir isotherm equation was found to be 666.67?mg Cu/g adsorbent. The effects of temperature, Cu²⁺ initial concentration, and CaCO₃ dosage on the removal capacity were also investigated using the three-level Box–Behnken experimental design method. The response surface modeling results demonstrated that under certain experimental conditions (i.e., T?=?26°C, [Cu²⁺]?=?200?mg/L, and [CaCO₃]?=?0.5?g/L), maximum removal capacity value (393.52?mg/g) was achieved.     

Enzymatic degradation of poly(propylene carbonate) and poly(propylene carbonate-co--caprolactone) synthesized via CO2 fixation

Poly(propylene carbonate) (PPC) and poly(propylene carbonate-co--caprolactone) (PPCCL) were synthesized via the zinc glutarate catalyzed copolymerization of carbon dioxide (CO₂) and propylene oxide (PO) without and with -caprolactone (CL), respectively. In addition, poly(-caprolactone) (PCL) was prepared via the homopolymerization of CL with the aid of methyl triflate catalyst. The polymer products were characterized in terms of their chemical compositions, molecular weights, and thermal properties. Films of these polymers were tested with a series of enzymes (four different families and a total of 18 enzymes) in a phosphate buffer in order to characterize their enzymatic degradabilities. This is the first report demonstrating that PPC films exhibit positive enzymatic degradability with Rhizopus arrhizus lipase, esterase/lipase ColoneZyme A, and Proteinase K. Moreover, PPCCL films exhibited positive enzymatic degradability with most of the enzymes utilized in our study, and thus PPCCL has an enzymatic degradability comparable to that of PCL. In particular, the PPCCL films exhibit excellent enzymatic degradability with Pseudomonas lipase, Rhizopus arrhizus lipase, and esterase/lipase ColoneZyme A. Considering its excellent enzymatic degradability, the PPCCL terpolymer has potential biomedical applications. In conclusion, ZnGA-catalyzed copolymerizations of CO₂ and PO with or without CL are chemical fixation processes of CO₂ that can be used to produce enzyme-degradable aliphatic polymers.