Hp 8453 uv vis spectrometer

X-ray diffraction (XRD), thermogravimetry analysis (TGA) and UV–VIS absorption spectra were used to characterize the crystalline structure, decomposition behavior, pH- and light-responsiveness of CNCs, CNCs-IBBr, and PMMAZO-grafted CNCs, respectively. XRD measurements were performed on a D8 ADVANCE wide angle X-ray diffractometer system (Bruker Corporation, Karlsruhe, Germany). The diffracted intensity of Cu Kα radiation (k = 0.1542 nm; 40 kV and 40 mA) was measured in a 2θ range between 5° and 60°. TGA was made using a seven-series thermal analysis system (PerkinElmer, Waltham, MA, USA). Samples were heated from room temperature to 600 °C at 10 °C/min in a dynamic nitrogen atmosphere at a flow rate of 25 mL/min. The UV–VIS absorption spectra were recorded using an HP-8453 UV–VIS spectrometer (Agilent, CA, USA). The number-average molecular weight (Mn) and molecular weight distribution (MWD) of the polymer cleaved from PMMAZO-grafted CNCs were measured on a GPCMax VE201 gel permeation chromatography (GPC) (Viscotek Co., Houston, TX, USA) equipped with three columns PAA-202-204-205 and three detectors: a viscometer, light scattering, and IR detector. The calibration was made with poly (ethylene oxide) standards.