Thermal Analysis of Amphiphilic Quaternary Ammonium Chitosan Derivatives

The thermal behaviour of amphiphilic systems involving (5-pentyl)trimethylammonium and dodecyl aldehyde-modified chitosans was studied. These amphiphilic chitosan derivatives were synthesized and characterized by 1HNMR and ATR-FTIR spectroscopies. Thermogravimetry (TGA) and differential scanning calorimetry (DSC) were used to determine their properties. It was found that the modification of the chitosan structure affects directly its thermal properties. The temperature at which water is released from the compounds showed that when adding the hydrophilic substituent water originally bound to an -NH2 group will bind to a less stronger >NH group requiring lower temperatures to be released. The addition of the hydrophobic C12 substituent confers a more micelle-like structure to the compound, leaving some water molecules within the core of the micelle, making its release more difficult. The decomposition peak observed around 300 °C, corresponding to the decomposition of the chitosan rings, is split in two peaks when adding the substituents, indicating the influence of the substituents on the ring decomposition reactions.