Arx 500 nmr spectrometer

The FTIR spectra were recorded on a Bruker Vector 22 FT-IR spectrophotometer (Hangzhou, China) by using thin films on KBr pellets. The ¹H and ¹³C NMR spectra were recorded on a Bruker ARX 500 NMR spectrometer or Bruker ARX 400 (Hangzhou, China) in chloroform-d (or methanol-d and DMSO-d6) using tetramethylsilane (TMS; δ = 0 ppm) as an internal standard. Molecular weights (M_w, M_n) and polydispersity indexes (PDI, M_w/M_n) of the polymers were estimated by using a Waters PL-GPC-50 gel permeation chromatography (GPC) system equipped with a refractive index (RI) detector (Hangzhou, China). A set of monodisperse polystyrene standards covering the molecular weight range of 10³–10⁷ were used for molecular weight calibration. The centrifugation process was done on the Siemensstr 25 D-78564 Z-326 type centrifugal machine (Hangzhou, China) The thermogravimetric analysis (TGA) was conducted on a Pyris 6 thermogravimetric analyzer (Perkin-Elmer, Hangzhou, China) under N₂ atmosphere at a heating rate of 20 °C·min⁻¹. The UV–Vis absorption spectra and fluorescence spectra were recorded on a Varian CARY 100 Bio UV–Vis spectrophotometer (Hangzhou, China) and a Shimadzu RF-5301PC spectro-fluorophotometer (Hangzhou, China).