Synthesis And Properties Study Of Low DP And Narrow Molecular Weight Distribution Chitosan Surfactants

With the increasing depletion of fossil resources and environmental contamination, developing green surfactant which is environmentally friendly, biodegradable and renewable is an important direction for new surfactant product. Low DP and narrow molecular weight distribution chitosan, the degradation product of chitin—a common polysaccharide found in exoskeleton of arthropods such as shrimps and crabs as well as the cell wall of fungi, is attracting widespread attention due to its properties such as non-toxicity, biodegradability and biocompatibility. In this paper, two types of low DP and narrow molecular weight distribution chitosan surfactants were synthesized based on low DP and narrow molecular weight distribution chitosan. The main work and results are as follows:(1)In this paper, low DP and narrow molecular weight distribution chitosan LNCS12, LNCS16, LNCS20are prepared by microwave-assisted hydrogen peroxide degradation. After that, the structures of the degradation product, low DP and narrow molecular weight distribution chitosan were characterized through Gel Filtration Chromatography (GFC),’H NMR, IR, etc. The spectra of’H NMR, IR showed that only the0-1,4glucoside bonds in chitosan were fractured during the degradation process, while the basic chemical structure of chitosan still remained. Chitosan molecular weight and molecular weight distribution index were characterized by GFC.(2)Two types of surfactants were synthesized from low DP and narrow molecular weight distribution chitosan:nonionic surfactants and anion surfactants. Further studies were based on effects of the length of hydrophobic group of the product on its solubility, surface activity, emulsifying property, foam property, wetting property and compatibleness. The studies also included how degree of polymerization of the reactant affected the properties of anion surfactants. The experimental results showed that both types of surfactants were soluble in water; both types of surfactants increased surfactant activities as chain length of hydrophobic group increased. Also, both nonionic surfactants and anion surfactants had certain emulsifying property and hygroscopicity; the former also possessed good compatibleness, while the latter possessed good foam ability. However, the application of anion surfactant may be concerned with the DP of low DP and narrow molecular weight distribution chitosan. Generally, both types of low DP and narrow molecular weight distribution chitosan surfactants are likely to be applied in environmental protection, medicine, cosmetics and food industries etc.