G2500pwxl columns

SEC was performed using a high-performance liquid chromatography system consisting of an AS-2057i Plus autosampler (Jasco, Tokyo, Japan), DG-2080-53 degasser (Jasco), PU-2080i Plus pump (Jasco), CO-965 column oven (Jasco), RI-2031 Plus refractive index detector (Jasco), and a combination of TSKgel G4000PW_XL and G2500PW_XL columns (300 mm × 7.8 mm internal diameter) (Tosoh, Tokyo, Japan). The sample solutions (10 mg/mL, 50 μL) were injected into the system and eluted with 100 mM NaNO₃ solution at a flow rate of 1 mL/min at 40 °C. The relative number-average molecular weight (M_n,SEC) and molecular weight distribution (M_w/M_n) were calculated from a calibration curve of standard poly(ethylene glycol) (PEG; Agilent Technologies, Wilmington, DE, USA).

¹H nuclear magnetic resonance (NMR) spectra were recorded in D₂O at 25 °C using a Bruker Avance III 400 MHz spectrometer (Bruker BioSpin, Rheinstetten, Germany). Fourier transform infrared (FT-IR) spectra were recorded on a Spectrum 100 FT-IR spectrometer (Perkin Elmer, Wellesley, MA, USA). The samples were ground to powder form, which was blended with KBr to prepare pellets for measurements. Aqueous-phase size exclusion chromatography (SEC) measurements were performed using a high-performance liquid chromatography setup consisting of an AU-950 autosampler (Jasco, Tokyo, Japan), PU-980 pump (Jasco, Tokyo, Japan), DG-2080-53 degasser (Jasco, Tokyo, Japan), CO-965 column oven (Jasco, Tokyo, Japan), RI-2031 Plus refractive index detector (Jasco, Tokyo, Japan), and a combination of TSKgel G4000PW_XL and G2500PW_XL columns (300 mm × 7.8 mm ID; Tosoh, Tokyo, Japan). The sample solutions (10 mg mL⁻¹, 50 μm) were injected into the system and eluted with a 100 × 10⁻³ M NaNO₃ solution at a flow rate of 0.4 mL min⁻¹ at 40 °C [30 (link)].