ABSTRACT
Carboxyl-type boronic acid copolymers (CBACs) were synthesized by a radical polymerization method and used for the preparation of polyvinyl alcohol (PVA)-based composite membranes via a solution mixture method. The as-prepared composite membranes exhibited a water uptake (WR) of 122.6-150.0%, an ion exchange capacity (IEC) of 0.0147-0.0518 mmol g-1, and excellent mechanical (elongation at break (Eb) of 103.8-148.4%, tensile strength (TS) of 38.7-58.6 MPa) and thermal stability. The alkali resistances of the as-prepared membranes were tested by immersing the samples into 2 mol L-1 NaOH solutions at 25 °C for 60 h, and the results were encouraging: the mass loss and swelling degree of the as-prepared membranes were in the ranges of 1.9-5.9% and 222.6-241.9%, respectively. The separation performances of the as-prepared membranes were evaluated by the diffusion dialysis (DD) process with an NaOH/Na2WO4 mixture at room temperature. The results demonstrated that the dialysis coefficients of hydroxide (UOH) were in the range of 0.0147-0.0347 m h-1, and the separation factors (S) were in the range of 29.5-62.6. The introduced carboxyl groups from CBACs and the -OH groups from PVA were both deemed to play significant roles in the promotion of ion transport: the -COO- groups formed negatively charged transport channels for Na+ by electrostatic attraction, and the -OH groups promoted the transport of OH- via hydrogen bonding.
ABSTRACT
Colorization for fabricating aluminum pigments has broad application prospects in recent years. In this study, yellow-colored aluminum pigments with the double-layer structure Al@SiO2@PFMV were prepared using a sol-gel method. A crosslinked copolymeric dye (PFMV) was firstly synthesized by radical polymerization using vinyl triethoxysilane (VTES) and a small molecular dye (FGMAC) as monomers. Then, colored aluminum pigments were prepared by hydrolysis and condensation of the copolymers on the surface of aluminum pigments. SEM, AFM, FTIR, and XPS were used to characterize the surface morphology and chemical structure of the colored aluminum pigments. It was found that the colored aluminum pigments have a heterogeneous and smooth surface layer. The anticorrosion results showed that the colored aluminum pigments had better chemical stability with significantly improving corrosion resistance compared to raw aluminum pigments and Al@SiO2 with the single-layer coating. Chromatism analysis indicated that the lightness of Al@SiO2@PFMV pigments decreased slightly and the color changed from silver-gray to yellow.