1260 infinity 2 multi detector

The molecular weight
and polydispersity index of the AcSL and AcIL samples were determined
by using gel permeation chromatography (Agilent 1260 Infinity II Multi-Detector).
This system was equipped with PLgel 5 μm mixed D columns (300
× 7.5 mm) and a PLgel 5 μm guard column. The lignins were
dissolved in DMF at a concentration of 0.1 mg·ml^–1 and filtered through 0.22 μm nylon filter. The injected volume
of the lignin solution was 80 μL.

FTIR spectra were recorded on an Agilent Cary 630 equipped with an ATR accessory. Liquid ¹H NMR analysis was performed on a Bruker 300 instrument operating at 300 MHz with an acquisition time of 1.9 s. Samples were dissolved in CDCl₃ or DMSO d-6 (a TMSPA-based polymer) and the residual solvent peak was used for calibration. The solid-state ¹³C NMR spectrum was recorded on a Bruker Avance III HD operating at 100.60 MHz, using a triple-resonance 1.9 mm MAS probe in double resonance mode. The sample had a mass of 15 mg and the spinning frequency was 20 kHz. ¹³C spectra were obtained using 1.5 ms cross-polarization ramped from 70–100% of the maximum amplitude or a 90° pulse. The molecular weight distribution (Mn, Mw and PDI) was determined with a GPC (1260 Infinity II Multi-detector from Agilent) equipped with triple detection (LS at 690.0 nm, viscosity, and RI) and operating at 25 °C with THF as the eluent. The columns were Agilent (Varian) PL-Gel mixed-B 10 mm.