Study on hydrogen bonds of carboxymethyl cellulose sodium film with two-dimensional correlation infrared spectroscopy

Carboxymethyl cellulose is widely used in many industrial aspects and also in laboratory due to its good biocompatibility. However, special researches on infrared especially aiming at the hydrogen bonds structure of carboxymethyl cellulose were relatively poor. We demonstrate here a full view of infrared spectroscopy in the temperature range of 40–220 °C, mainly aiming at the hydrogen bonds in the NaCMC film. The two important transition points was defined with DSC and together with Infrared analysis, that is, 100 °C corresponding to the complete loss of water molecules and 170 °C to the starting temperature point the O6H6 being oxidized. The series of IR spectra during heating from 40 to 220 °C was analyzed by the two-dimensional correlation method. We found that the water molecules bound with CO groups and OH groups. With the evaporating of water molecules, the hydrated CO groups gradually transited into non-hydrated CO groups. As the temperature continued to increase, the intrachain hydrogen bonds were weakened and transited into weak hydrogen bonds. When the temperature was higher than 170 °C, the O6H6 groups were gradually oxidized and thus the interchain hydrogen bonds formed between CH₂COONa groups and O6H6 were weakened. In summary, we defined the main sorts of hydrogen bonds in carboxymethyl cellulose and pictured the changes of the hydrogen bonds structure during heating process, which may provide for the further application in both industry aspects and laboratory use.