Phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-maleic anhydride) in the presence of hollow silica nanotubes

Multifunctionality of Reduced Graphene Oxide in Bioderived Polylactide/Poly(Dodecylene Furanoate) Nanocomposite Films

This work reports on the first attempt to prepare bioderived polymer films by blending polylactic acid (PLA) and poly(dodecylene furanoate) (PDoF). This blend, containing 10 wt% PDoF, was filled with reduced graphene oxide (rGO) in variable weight fractions (from 0.25 to 2 phr), and the resulting nanocomposites were characterized to assess their microstructural, thermal, mechanical, optical, electrical, and gas barrier properties. The PLA/PDoF blend resulted as immiscible, and the addition of rGO, which preferentially segregated in the PDoF phase, resulted in smaller (from 2.6 to 1.6 µm) and more irregularly shaped PDoF domains and in a higher PLA/PDoF interfacial interaction, which suggests the role of rGO as a blend compatibilizer. rGO also increased PLA crystallinity, and this phenomenon was more pronounced when PDoF was also present, thus evidencing a synergism between PDoF and rGO in accelerating the crystallization kinetics of PLA. Dynamic mechanical thermal analysis (DMTA) showed that the glass transition of PDoF, observed at approx. 5 °C, shifted to a higher temperature upon rGO addition. The addition of 10 wt% PDoF in PLA increased the strain at break from 5.3% to 13.0% (+145%), and the addition of 0.25 phr of rGO increased the tensile strength from 35.6 MPa to 40.2 MPa (+13%), without significantly modifying the strain at break. Moreover, rGO decreased the electrical resistivity of the films, and the relatively high percolation threshold (between 1 and 2 phr) was probably linked to the low aspect ratio of rGO nanosheets and their preferential distribution inside PDoF domains. PDoF and rGO also modified the optical transparency of PLA, resulting in a continuous decrease in transmittance in the visible/NIR range. Finally, rGO strongly modified the gas barrier properties, with a remarkable decrease in diffusivity and permeability to gases such as O2, N2, and CO2. Overall, the presented results highlighted the positive and sometimes synergistic role of PDoF and rGO in tuning the thermomechanical and functional properties of PLA, with simultaneous enhancement of ductility, crystallization kinetics, and gas barrier performance, and these novel polymer nanocomposites could thus be promising for packaging applications.

Fast and effective recovery of Au(III) from aqueous solution by a N-containing polymer

In this work, a N-containing polymer was successfully synthesized by one-step treatment with 3-amine-1,2,4-triazole ligands and Zn(II) using the thermal solvent method, and employed to recover Au(III) from water. The adsorption kinetics was comprehensively studied through kinetics models including pseudo-first-order model, pseudo-second-order model, moving boundary model and Weber-Morris model. It is found that the overall adsorption rate was determined by chemical adsorption, and the rate-limiting step of diffusion steps is film diffusion. Rising temperature can improve the adsorption rate significantly, making the adsorption equilibrium time be reduced from 6 h at 298 K to 2 h at 318 K. The adsorption isotherm can be described well by Sips model, indicating it is a heterogeneous adsorption. The material shows high adsorption capacity towards Au(III) up to 1073 mg/g. It shows strong affinity towards Au(III) in the mixture solutions containing Au(III), Cu(II), Zn(II), Co(II), Cd(II), Pb(II) and Ni(II) ions. The material can be easily and completely desorbed by thiourea solution and still maintains its adsorption performance only with a slight decrease after three cycles. Combined with studies on pH influence, adsorption kinetics, adsorption isotherm and XPS analysis, it can be concluded that the adsorption mechanism could be attributed to electrostatic interaction, the coordination of the Zn-OH and -C-N/-CN- with Au(III), and partial reduction of Au(III) to Au(I) by -NH group on the polymer. The N-containing polymer is an excellent candidate for Au(III) recovery efficiently and selectively from aqueous solution.