Novel water-soluble chitosan derivative prepared by graft polymerization of dicyandiamide: synthesis, characterisation, and its antibacterial property

作者：Khalil Esra Suliman^*; Saad Bahruddin; Negim El Sayed Moussa; Saleh Muhammad Idiris

来源：Journal of Polymer Research, 2015, 22(6): 116.

DOI：10.1007/s10965-015-0756-9

• Chitosan
• Dicyandiamide
• Potassium persulphate
• Grafting polymerization

Novel water soluble chitosan derivative of dicyandiamide chitosan (DCDA-g-CS) was synthesized by grafting polymerization of dicyandiamide DCDA onto chitosan CS. The presence of a new absorption peak in the infrared region of nitrile at 2297 cm(-1) and NH at 1635 cm(-1) of DCD-Ag-CS and the chemical shift of C-13 NMR at 120 and 162 ppm due to the presence of nitrile and carbon in DCDA clearly shows that the grafting process has taken place. The strong signal in the H-1 NMR at 2.5 ppm could be assigned to the four protons in the amino group of DCDA, further confirms the formation of DCDA-g-CS. The polymer has shown to undergoing three steps of thermal degradation. The first stage was between 30 and 157 degrees C, followed by degradation step up to 350 degrees C and continuously degraded up to the high temperature set at 850 degrees C. The rate of degradation in the second stage which is slightly faster was considered as the rate determining step. The value of T-g was increased to 92.75 degrees C in DCDA-gCS due to the considerable amount of DCDA was grafted onto the CS. The DCDA-g-CS was more soluble in water due to the decrease in crystallinity of chitosan after grafting as shown from X-ray diffraction spectra. The DCDA-g-CS shows high antibacterial activity at pH 7.0 and pH 4.0 the minimum inhibitory concentration (MIC) of gram-negative bacteria E. coli ATCC25922, the MIC at pH 7 and pH 4.0 were 62.5 and 125 mu g/mL respectively and gram-positive bacteria S. aureus ATCC 29213, the MIC at pH 7 and pH 4 were 62.5 and 125 mu g/mL respectively.

• 出版日期2015-5-24