Q500 system

XPS were measured by an Escalab 250 (Thermo Fisher Scientific, USA) instrument that employs Al Kα radiation. FTIR were conducted on a Nicolet iS10 system (Thermo Fisher Scientific, USA) in the range of 4000–700 cm⁻¹. TGA was characterized by a Q500 system (TA Instruments, USA) under nitrogen atmosphere with a heating rate of 10 °C min⁻¹. DSC measurement was carried out on a Q2000 instrument (TA Instruments, USA) under nitrogen atmosphere using a heating rate of 10 °C min⁻¹. Elemental analysis measurement was conducted using a Vario Micro Cube (Elementar, Germany). UV–Vis spectrum analysis was done using a Lambda 750 spectrophotometer (Perkin Elmer, USA). The magnetic property was tested using VSM on a Squid-VSM system (Quantum Design, USA) at 80 °C. Cross-sectional membrane samples for TEM (Tecnai G² F20 field emission TEM, FEI, USA) were embedded in epoxy resin and solidified at 100 °C for 2 h, and then cut on an EMUC6 ultramicrotome (Leica, Germany). Elements W, Fe, and S were detected and mapped by an Enfinium 977 EELS spectrometer (Gatan, USA), and the mapping time was 2 s. The particle size of PWA was estimated by DLS technique on a Zetasizer nano ZS90 apparatus (Malvern Instruments, UK). Cross-sectional membrane samples for SEM (SU8010 field emission SEM, Hitachi, Japan) were freeze-fractured in liquid nitrogen and vacuum sputtered with a thin layer of gold.

¹H NMR spectra were recorded on a JEOL ECS-400 spectrometer (JEOL, Tokyo, Japan) operated at 400 MHz. The number-average molecular weights (M_n) and molecular weight distributions (M_w/M_n) of the product polymers were determined via size-exclusion chromatography (SEC) in DMF containing 100 mM LiCl at 40 °C on two hydrophilic polymer gel columns [Tosoh α-M + α-3000 (7.8 mm i.d. × 30 cm) (Tosoh Corporation, Tokyo, Japan); flow rate of 1.0 mL/min] (for poly(4VG)) connected to a JASCO PU-2080 precision pump and a JASCO RI-2031 detector (JASCO, Tokyo, Japan). The columns were calibrated against standard polystyrene samples (Agilent Technologies, Santa Clara, CA, USA; M_p = 580–3,053,000, M_w/M_n = 1.02–1.23). The glass transition temperature (T_g) of the polymers was recorded on a Q200 differential-scanning calorimeter (TA Instruments, Inc., New Castle, DE, USA), and the T_g values were obtained from the second scan after removing the thermal history. The samples were first heated to 210 °C at 10 °C/min, equilibrated at this temperature for 10 min, and cooled to −60 °C at 5 °C/min. After holding at this temperature for 5 min, the samples were then reheated to 210 or 260 °C at 10 °C/min. The thermogravimetric analyses (TGA) were performed on a Q500 system (TA Instruments Inc.) at 5 °C/min under a N₂ gas flow.

X-ray diffraction (XRD) measurements were performed using a Philips
X’Pert-Pro diffractometer using monochromatic Cu Kα radiation
(40 mA, 40 kV) with a step width of 0.013° (2θ). JCPDS
cards were used to identify the crystalline phases. Transmission electron
microscopy (TEM) images of composite samples were recorded using a
TEM/STEM JEOL JEM 2200 fs microscope operating at 200 kV. Prior to
TEM analysis, powders of the sample were prepared and dispersed in
water and a drop of the finely dispersed sample was put on a Lacey
Carbon film copper TEM grid. The TEM grid with the sample droplet
was dried overnight in an oven at 40 °C. Fifty particles at random
locations were analyzed by Image J to determine the particle size
and distribution. HRTEM images were used to determine the lattice
plane distance using the Image J software. Thermogravimetric analysis
(TGA) was carried out to study the thermal behavior of the prepared
materials using a Q500 system from TA Instrument (New Castle, DE);
the samples were heated from 50 to 700 °C at 10 °C/min in
nitrogen or air (gas flow of 60 mL/min). The tests were performed
by placing about 10 mg of the sample in open alumina pans.