|
Bacterial cellulose (BC) has a high degree of polymerization, high purity, finer fibers than other common characteristics of plant cellulose, currently on chemical modification of bacterial cellulose and its derivatives Performance few studies. In this thesis, the production of bacterial cellulose coconut water as raw material, through etherification chemical modification of bacterial cellulose prepared 2,3,6-0-alkyl bacterial cellulose ,6-0-(4,4 '- double-methoxy-trityl (DMT)) bacterial cellulose and carboxymethyl cellulose three derivatives of bacterial effects of reaction conditions on the reaction of the product structure was characterized. This thesis extends the bacterial cellulose chemical modification methods, to promote the use of high value bacterial cellulose has a better theoretical guidance. (1) in DMAc / LiCl solution system, with alkyl bromide as the etherifying agent, NaHH alkalizing agent is prepared 2,3,6-O-ethyl bacterial cellulose ,2,3,6-O- propyl bacterial cellulose ,2,3,6-O-isopropyl-bacterial cellulose ,2,3,6-O-butyl-bacterial cellulose. In the 2,3,6-O-ethyl bacterial cellulose in the reaction system, a low amount of sodium hydride, the resulting ethyl substituted bacterial cellulose is low, when bacterial cellulose and sodium hydride ratio of 27.8:1, the changing the amount of ethyl bromide obtained a degree of substitution of 0.93-2.64 bacterial 2,3,6-O-ethyl cellulose, NMR, FTIR have confirmed ethyl substituted in the 2,3,6 position; XRD results show alkoxy Base modification destroyed the crystal structure of the bacterial cellulose, bacterial cellulose crystallinity decreased alkyl; TG results showed that bacterial cellulose alkyl weak intermolecular forces, thermal stability decreased; Elementary analysis showed that ethyl bromide was ethyl substituent bacterial cellulose obtained is higher than the other three alkyl substituted bacterial cellulose. Bacterial cellulose alkyl tested in chloroform, ethanol, DMSO, toluene (30%) / ethanol mixed solvent system such as solubility. (2) in DMAc / LiCl solution system, NaHH of alkalizing agent, 4,4 '- methoxy trityl chloride (DMTCl) 6 of bacteria selectively modified cellulose, prepared 6 - O-(4,4 '- Dimethoxytrityl) bacterial cellulose (DMTCell), experimental results show an increase in a range DMTCl amount, reaction time and can improve the degree of substitution DMTCell, when bacterial cellulose DMTCl molar ratio of 8.4:1, temperature 70 ℃, reaction time 20 h when, DMTCell degree of substitution of 0.94. NMR, FTIR indicated that the product is optionally substituted 6-position. High degree of substitution DMTCell soluble in DMSO. (3) the reaction medium in ethanol, monochloroacetic acid as an etherifying agent, NaOH as the base, prepared by modification of the bacterial cellulose carboxymethyl bacterial cellulose (CMC). Experimental results show, 25 ℃ ultrasonic alkalized 40 min, an acid with a molar ratio of the amount of bacterial cellulose 4.5:1, etherification stage I 30 min, 50 ℃, ether Ⅱ stage 90 min, 60 ℃, the system The degree of substitution of carboxymethyl cellulose bacteria highest, 0.48. FTIR confirmed the product structure, there carboxymethylcellulose. Sodium carboxymethyl cellulose having good water bacterial solubility, degree of substitution of 0.32-0.48 Sodium carboxymethyl cellulose can be dissolved in water bacteria. Test results show that the viscosity of bacterial cellulose, sodium carboxymethyl polyelectrolyte solution has obvious effect.
|