Preparation And Properties Of Quaternary Ammonium Salt Of P-methoxycinnamoyl Chitosan

In this paper, quaternary ammonium salt of p-methoxycinnamoyl chitosan (QMOC-CS) was synthesized and its properties were studied.Firstly, synthetic routes and synthesis condition of QMOC-CS were studied. RouteⅠ: P-methoxycinnamoyl chitosan (MOC-CS) was synthesized by p-methoxycinnamic acid (MOC) and chitosan through a carbodiimide mediated reaction. The structure of MOC-CS and the substitution of p-methoxy cinnamic acid were characterized by UV spectrum. The reaction condition was optimized by investigating the effect of reaction time, dehydration dosage and the ratio of CS to MOC on the substitution degree of p-methoxy cinnamic acid. The optimal reaction condition was as following: reaction time of 18 hours, the ratio of the chitosan/MOC=1:1, the ratio of dehydration/chitosan =5:3. The degree of substitution was 10.9%. MOC-CS was further quaternized by 3-chloro-2-hydroxypropyl trimethylammonium chloride (Quat-188). The obtained QMOC-CS was characterized by 1H-NMR. The degree of quaternized was measured by Kjeldahl method, colloid titration and silver nitrate titration. The effect of temperature, time and material ratio on degree of quaternized were investigated. The optimal reaction condition was : reaction time of 10 hours, the ratio of chitosan/ Quat-188=1:3, 80℃. The degree of quaternized was 86.1%. RouteⅡ: the quaternary ammonium salt of chitosan (Q-CS) was synthesized by using chitosan and Quat-188. The Q-CS was further acetylated by p-methoxycinnamic acyl chloride (MAC) to get the QMOC-CS. The reaction condition was optimized by using the substitution degree and solubility as an objective. The optimal reaction condition was: 24 hours, the ratio of chitosan/MAC=1:2. The degree was 19.1%.Then, the properties of QMOC-CS were studied. The viscosity average molecular weight of the CS and QMOC-CS was determinated by viscometer, which showed that the molecular weight of QMOC-CS was almost the same as CS. CS was just soluble in water at below pH 6, but the QMOC-CS was found soluble in water at below pH 8.02, and the solubility of QMOC-CS was 13 g/L. QMOC-CS could adsorb on hair and the adsorbance of QMOC-CS increased as the concentration increased. In the environment of UV, the QMOC-CS absorbed on the hair could protect cuticle and prevent the decomposition of tryptophan in hair. QMOC-CS would be complex with AES in the shampoo formulation, whereas, QMOC-CS had a good compatibility in the hair conditioner formulation. QMOC-CS had a better retention moisturizing properties than CS. The Trubidimetry was used to study the antibacterial activity of QMOC-CS. The results show that QMOC-CS had antibacterial activity at a low concentration.