N-vinylpyrrolidone and 4-vinyl Benzylchloride Copolymers: Synthesis, Characterization and Reactivity Ratios

Statistical Copolymers of N-Vinylpyrrolidone and Isobornyl Methacrylate via Free Radical and RAFT Polymerization: Monomer Reactivity Ratios, Thermal Properties, and Kinetics of Thermal Decomposition

The synthesis of statistical copolymers of N-vinylpyrrolidone (NVP) with isobornyl methacrylate (IBMA) was conducted by free radical and reversible addition-fragmentation chain transfer (RAFT) polymerization. The reactivity ratios were estimated using the Finemann-Ross, inverted Fineman-Ross, Kelen-Tüdos, extended Kelen-Tüdos and Barson-Fenn graphical methods, along with the computer program COPOINT, modified to both the terminal and the penultimate models. According to COPOINT the reactivity ratios were found to be equal to 0.292 for NVP and 2.673 for IBMA for conventional radical polymerization, whereas for RAFT polymerization and for the penultimate model the following reactivity ratios were obtained: r11 = 4.466, r22 = 0, r21 = 14.830, and r12 = 0 (1 stands for NVP and 2 for IBMA). In all cases, the NVP reactivity ratio was significantly lower than that of IBMA. Structural parameters of the copolymers were obtained by calculating the dyad sequence fractions and the mean sequence length. The thermal properties of the copolymers were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and differential thermogravimetry (DTG). The results were compared with those of the respective homopolymers.

Novel zwitterionic inorganic-organic hybrids: synthesis of hybrid adsorbents and their applications for Cu2+ removal

A series of zwitterionic hybrid adsorbents were prepared via the ring-opening polymerization of pyromellitic acid dianhydride (PMDA) and N-[3-(trimethoxysilyl)propyl] ethylene diamine (TMSPEDA), and a subsequent zwitterionic process as well as sol-gel reaction. Their applications for Cu(2+) removal by adsorption were performed. FTIR spectra confirmed the step products. TGA revealed that the initial decomposition temperature (IDT) of these zwitterionic hybrid adsorbents could arrive at near 150°C. DSC showed that T(g) values decreased with an increase in PMDA content in the hybrid matrix. Ion-change capacity (IEC) revealed that the cation-exchange capacities (CIECs) and anion-exchange capacities (AIECs) of these hybrid adsorbents were within the range of 9.13-11.49 and 4.97-6.28 mmol g(-1), respectively. Meanwhile, the CIECs and AIECs exhibit an opposite change trend as PMDA content increases. Adsorption experiment indicated that their adsorptions for Cu(2+) ions followed Lagergren second-order kinetic model, surface adsorption and intraparticle diffusion mechanisms might be the major process. These findings demonstrated that they are promising absorbents for the separation and recovery of Cu(2+) ions from contaminated water.