Synthesis Of Chitosan Derivatives And Study On Their Application In Cosmetics

In this paper, which introduces the synthesis of high degree of deacetylation chitosan,N,N-dimethyl chitosan,and the water-soluble derivatives: N,N,N-trimethyl chitosan iodide (TMCI),N,N,N-trimethyl chitosan methylsulfate(TMCS), and study some of their properties as the additives when used in cosmetics.Begin with chitosan with 70 % degree of deacetylation, the optimized way to prepare high degree of deacetylation chitosan is: chitosan is mixed with 45 % NaOH solution at 80℃for 8h by intermittent method for twice. The degree of deacetylation can be improved to above 90 %, the molecule weight is determined to be 3.2×105.Then N,N-dimethyl chitosan is synthesized by chitosan with excessive formic acid and formaldehyde. The optimized condition is at 70℃for 5 h, n(chitosan):n(formaldehyde):n(formic acid) =1∶8∶6.The quaternization of N,N-dimethyl chitosan is carried out by methyl iodide in NMP and water solution at 36℃to produce N,N,N-trimethyl chitosan iodide(TMCI), the product subsequently is exchanged the iodide ion with chloride to afford N,N,N-trimethyl chitosan chloride (TMCC). The highist degree of the quaternization (DQ) reaches to 80 % by titration method, better than any other reports. The influence on DQ of TMCI includes the reactive time, materiel proportion and the solution and they are studied in this thesis.Based on the N,N-dimethyl chitosan, the dimethyl sulfate is used to get a novel chitosan derivatives: N,N,N-trimethyl chitosan methylsulfate(TMCS). The reaction is carried out in NMP, with stirring for 18 h at 45℃. TMCS is characterized using IR and 1H-NMR spectroscopy, some physical properties are analyzed by thermogravimetry (TG) and differential scanning calorimetry(DSC). After recrystallization, the DQ of product is determined to be 60 % by elementary analysis.The aim to research on the properties is to study the relation between it with DQ and MW. Quaternary ammonium salt of chitosan can dissolve in pH1～14 water, and express the characteristics of cation surface active agent; The emulsification of TMCI datas indicates that products with 78.7 %DQ﹥56.8 %DQ﹥47 %DQ﹥SDS; The antioxidative activity of TMCI is also studied, the results reveals that the scavenging activity on·OH reaches up to 40.2 % and the scavenging activity on O2-··is 65.6 % when TMCI with 33. 9 %DQ, and with the increase of DQ, the scavenging activities on both·OH and O2-·decreases. The moisture retention and absorption properties of TMCI are researched by weight method in manual climate box. The moisture retention of TMCI is tested comparing with other moisture retention reagents. Comparison with the loss of moisture, the moisture retention of all reagents is obtained, which is determined on the definite conditions (25℃and humidity 40 %, 60 % and 80 % individually). At the same concentration and condition, especially at humidity 60% and 80 %, the moisture retention of TMCI is best than any other reagents even HA. The moisture adsorbability of TMCI with 78.7 %DQ is 300 % after 18 h in 80 % humidity. All results show that TMCI has excellent moisture retention and absorption ability. Due to the abundant material and excellent properties, quaternary ammonium salt of chitosan will be used the in cosmetics as a potential additive.