木聚糖基复合材料的结构组装与性能研究
发布时间：2019-07-09 17:53
【摘要】：环境污染与能源短缺等问题使得再生资源的开发与利用受到人们的广泛关注。半纤维素来自植物的细胞壁,是自然界中含量丰富、价格低廉的天然多糖,已被广泛应用在造纸、能源、食品以及生物医药等领域,逐渐成为一种可取代石化产品、无毒、可降解、环境友好的新型原料。但是,半纤维素复杂的糖组分、较高的分枝度以及无定形结构使得其只能进行低附加值利用。为了实现半纤维素的高值化利用,本研究采用半纤维素的模型物—木聚糖作为基材,一方面将木聚糖与另一种天然多糖(壳聚糖)进行结构组装,另一方面将木聚糖与无机纳米贵金属材料有效复合,发展了木聚糖基复合功能材料,并考察了其性能,主要研究内容包括:1、木聚糖/壳聚糖复合物的制备与性能探讨为了避免分别溶于碱性和酸性溶液的木聚糖和壳聚糖在混合时产生沉淀,使得两者之间的反应不能顺利进行,本研究将木聚糖和壳聚糖溶于同一种离子液体后进行美拉德反应,使得壳聚糖中的氨基与木聚糖中的还原性末端醛基接枝,最终生成大分子物质类黑精,即木聚糖-壳聚糖美拉德反应产物。结果证明,当木聚糖和壳聚糖两者质量比为1:1时更容易发生美拉德反应,此时得到的美拉德反应产物具有较高的抗氧化性能,有望用作食品抗氧化剂。另外,为了改善壳聚糖膜的性能,将壳聚糖膜浸入到不同浓度的木聚糖NaOH溶液中。在此过程中,木聚糖分子进入壳聚糖膜的缝隙中形成小的球结,随着木聚糖浓度的增加球结逐渐增大,并且木聚糖与壳聚糖之间也形成了较强的分子间相互作用力,当木聚糖浓度为3%时,得到致密光滑的木聚糖/壳聚糖复合膜。结果表明,此复合膜的拉伸强度、断裂伸长率以及抗紫外能力均随着木聚糖溶度的增加而增加,复合膜的水蒸汽透过率、吸水性以及氧气阻隔性能均优于壳聚糖膜,此复合膜也具有较好的疏水性。因此该复合膜与单纯壳聚糖膜相比更适用于食品包装膜。2、木聚糖绿色制备纳米金属材料及其性能研究以木聚糖作为还原剂和稳定剂,在微波条件下进行Tollens反应制备了纳米银,并得到木聚糖/纳米银复合材料,在加热条件下制备了纳米金,并得到木聚糖/纳米金复合材料。其中纳米银的最佳制备条件为:微波加热温度60~70°C,微波功率800 W,微波时间30 min,氨水浓度2%,木聚糖与AgNO3的比例50 mg:0.13 mmol,在此条件下生成的纳米银被木聚糖包裹、分散均匀、粒径分布为20~35 nm;纳米金的最佳制备条件为:木聚糖与HAu Cl4?4H2O的质量比0.15 g:15 mg,反应温度80°C,反应时间40 min,在此条件下得到的纳米金的粒径为10~30 nm,具有较窄的粒径分布。探讨得到的木聚糖绿色合成纳米贵金属的反应机理为:木聚糖的还原性末端基能将贵金属离子还原为贵金属单质,其本身也被氧化为羰基,在此过程中,木聚糖的主链只有轻微水解,但侧链有部分脱落;其后纳米贵金属的晶核不断长大,最终形成纳米粒子,而木聚糖中的羟基具有很高的电负性,能够包裹在纳米贵金属粒子表面成为稳定剂。此外,木聚糖/纳米银和木聚糖/纳米金复合材料分别能够对汞离子和半胱氨酸进行高灵敏度和特异性检测;其中木聚糖/纳米银复合材料对汞离子的最低检测限(LOD)能达到4.6 n M,在实际水样中对汞离子也有较好的检测效果;木聚糖/纳米金复合材料对半胱氨酸的检测限(LOD)为0.57μM,在血浆环境中也能对半胱氨酸进行检测。本研究一方面为纳米贵金属的绿色合成提供了新的途径,另一方面也将得到的纳米贵金属用于汞离子以及半胱氨酸的检测,从而实现了半纤维素的高值化利用。3、木聚糖-点击-壳聚糖季铵盐聚合物(Xylan-click-QCS)的合成及在纳米金属材料制备中的应用基于以上研究,本文将木聚糖与壳聚糖和纳米贵金属同时结合,以实现木聚糖的进一步高值化利用。在本研究中,首先将溴代丙炔与木聚糖反应生成丙炔基木聚糖;并将壳聚糖季铵化生成壳聚糖季铵盐,其6位羟基被对甲苯磺酰基取代后与叠氮钠反应生成叠氮化壳聚糖季铵盐,随后在铜(I)的催化下利用点击化学合成Xylan-click-QCS。然后利用Xylan-click-QCS制备了纳米银与纳米金,其中木聚糖中的还原性末端基以及壳聚糖季铵盐中的季铵基作为还原性基团能将金属离子还原成金属单质,而点击化学产物中的三唑环不仅能够为纳米贵金属粒子的生长提供原始位点,也能钝化生成的纳米金属粒子表面使其稳定存在。其中生成的纳米银粒径分布有两个范围:10~20 nm和2~5 nm,这说明除了纳米颗粒,此反应也生成了纳米银簇,将两者分离后可大大拓宽产物的应用范围;而生成的纳米金粒径分布为20~30 nm,与木聚糖合成的纳米金相比粒径分布更加均一。
文内图片：![常见半纤维素糖单元[8]](http://image.cnki.net/getimage.ashx?id=1015988422.nh0002)
图片说明：常见半纤维素糖单元[8]
[Abstract]:The problems of environment pollution and energy shortage make the development and utilization of renewable resources widely concerned. The hemicellulose comes from the cell wall of the plant, is a natural polysaccharide which is abundant in nature and low in cost, and has been widely used in the fields of paper making, energy, food and biological medicine, and has gradually become a novel raw material which can be substituted for petrochemical products, non-toxic, degradable and environment-friendly. However, a semi-cellulose complex sugar component, a higher degree of branching, and an amorphous structure makes it possible to make only low-value-added use. In order to realize the high-level utilization of hemicellulose, the research adopts a model of hemicellulose as a base material, and on the one hand, the xylan is structurally assembled with another natural polysaccharide (chitosan), and on the other hand, the xylan is effectively compounded with the inorganic nano-noble metal material, The preparation and properties of the xylan-based composite functional material were studied. The main contents of this study were as follows:1. The preparation and the properties of the xylan/ chitosan complex were discussed in order to avoid the precipitation of the xylan and the chitosan in the basic and acidic solution, so that the reaction between the chitosan and the chitosan is not carried out smoothly, and the xylan and the chitosan are dissolved in the same ionic liquid to carry out Maillard reaction, so that the amino groups in the chitosan are grafted with the reducing terminal aldehyde groups in the xylan, and finally the macromolecular substance type black essence is generated, Namely a xylan-chitosan Maillard reaction product. The results show that Maillard reaction is more likely to occur when the mass ratio of the xylan and the chitosan is 1:1, and the obtained Maillard reaction product has high antioxidant performance and is expected to be used as a food antioxidant. In addition, in order to improve the performance of the chitosan membrane, the chitosan membrane was immersed in a different concentration of the xylan NaOH solution. In the process, the xylan molecules enter into the gap of the chitosan membrane to form a small spherical junction, and as the increase of the concentration of the xylan increases gradually, a stronger intermolecular interaction force is formed between the xylan and the chitosan, when the concentration of the xylan is 3 percent, And a dense and smooth xylanase/ chitosan composite membrane is obtained. The results show that the tensile strength, elongation at break and the ultraviolet resistance of the composite membrane are increased with the increase of the solubility of the xylan, and the water vapor transmission rate, the water absorption and the oxygen barrier properties of the composite membrane are superior to that of the chitosan membrane, and the composite membrane also has good hydrophobicity. Therefore, the composite membrane is more suitable for the food packaging film than the pure chitosan membrane. And the xylan/ nano-silver composite material is obtained, and the nano-gold is prepared under the heating condition, and the xylan/ nano-gold composite material is obtained. The preparation conditions of the nano silver are as follows: the microwave heating temperature is 60 to 70 DEG C, the microwave power is 800W, the microwave time is 30 minutes, the ammonia concentration is 2 percent, the proportion of the xylan and the AgNO3 is 50 mg to 0.13 mmol, the nano silver generated under the condition is wrapped by the xylan, the dispersion is uniform, and the particle size distribution is 20 to 35 nm; The optimum preparation conditions of the nano-gold are as follows: the mass ratio of the xylan and the HAuCl4-4H2O is 0.15 g:15 mg, the reaction temperature is 80 DEG C, the reaction time is 40 min, the particle size of the nano-gold obtained under the condition is 10-30 nm, and the nano-gold has a narrow particle size distribution. The reaction mechanism of the obtained xylan green synthetic nano-noble metal is that the reductive end group of the xylan can reduce the noble metal ions into a noble metal simple substance, and the noble metal ion is also oxidized into a metal base, in which the main chain of the xylan is only slightly hydrolyzed, but the side chain is partially shed; And finally, the nano-particles are formed, and the hydroxyl groups in the xylan have high electronegativity and can be coated on the surface of the nano-noble metal particles to be a stabilizer. in addition, that xylan/ nano-silver and the xylan/ nano-gold composite material can carry out high-sensitivity and specific detection on the mercury ion and the cysteine, wherein the minimum detection limit (LOD) of the xylan/ nano-silver composite material to the mercury ion can reach 4.6 n-M, The detection limit of cysteine (LOD) was 0.57. m u.M, and cysteine was also detected in the plasma environment. on the one hand, the invention provides a new way for green synthesis of the nano-noble metal, and on the other hand, the obtained nano-noble metal is used for the detection of the mercury ions and the cysteine, The synthesis of xylan-click-chitosan quaternary salt-salt polymer (Xylan-click-QCS) and its application in the preparation of nano-metal materials are based on the above research. in the present study, first, the bromopropyne and the xylan are reacted to form the propargyl-xylan, and the chitosan quaternary salt is generated by the chitosan quaternary salt, and the 6-position hydroxyl group is replaced by the toluene sulfo-base and reacts with the sodium azide to generate the azido chitosan quaternary salt, Xylan-click-QCS is then chemically synthesized under the catalysis of copper (I). then the nano-silver and the nano-gold are prepared by using the Xylan-click-QCS, And the three-ring ring in the chemical product can not only provide the original site for the growth of the nano-noble metal particles, but also can passivate the surface of the generated nano metal particles to make the surface of the nano metal particle stable. wherein the generated nano-silver particle size distribution has two ranges of 10-20 nm and 2-5 nm, which indicates that the nano-silver cluster is formed in addition to the nano-particles, and the application range of the product can be greatly expanded after the nano-silver clusters are separated; and the generated nano-silver particle size distribution is 20-30 nm, Compared with the nano-gold synthesized by the xylan, the particle size distribution is more uniform.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O636.1;TB332
本文编号：2512327
文内图片：
图片说明：常见半纤维素糖单元[8]
[Abstract]:The problems of environment pollution and energy shortage make the development and utilization of renewable resources widely concerned. The hemicellulose comes from the cell wall of the plant, is a natural polysaccharide which is abundant in nature and low in cost, and has been widely used in the fields of paper making, energy, food and biological medicine, and has gradually become a novel raw material which can be substituted for petrochemical products, non-toxic, degradable and environment-friendly. However, a semi-cellulose complex sugar component, a higher degree of branching, and an amorphous structure makes it possible to make only low-value-added use. In order to realize the high-level utilization of hemicellulose, the research adopts a model of hemicellulose as a base material, and on the one hand, the xylan is structurally assembled with another natural polysaccharide (chitosan), and on the other hand, the xylan is effectively compounded with the inorganic nano-noble metal material, The preparation and properties of the xylan-based composite functional material were studied. The main contents of this study were as follows:1. The preparation and the properties of the xylan/ chitosan complex were discussed in order to avoid the precipitation of the xylan and the chitosan in the basic and acidic solution, so that the reaction between the chitosan and the chitosan is not carried out smoothly, and the xylan and the chitosan are dissolved in the same ionic liquid to carry out Maillard reaction, so that the amino groups in the chitosan are grafted with the reducing terminal aldehyde groups in the xylan, and finally the macromolecular substance type black essence is generated, Namely a xylan-chitosan Maillard reaction product. The results show that Maillard reaction is more likely to occur when the mass ratio of the xylan and the chitosan is 1:1, and the obtained Maillard reaction product has high antioxidant performance and is expected to be used as a food antioxidant. In addition, in order to improve the performance of the chitosan membrane, the chitosan membrane was immersed in a different concentration of the xylan NaOH solution. In the process, the xylan molecules enter into the gap of the chitosan membrane to form a small spherical junction, and as the increase of the concentration of the xylan increases gradually, a stronger intermolecular interaction force is formed between the xylan and the chitosan, when the concentration of the xylan is 3 percent, And a dense and smooth xylanase/ chitosan composite membrane is obtained. The results show that the tensile strength, elongation at break and the ultraviolet resistance of the composite membrane are increased with the increase of the solubility of the xylan, and the water vapor transmission rate, the water absorption and the oxygen barrier properties of the composite membrane are superior to that of the chitosan membrane, and the composite membrane also has good hydrophobicity. Therefore, the composite membrane is more suitable for the food packaging film than the pure chitosan membrane. And the xylan/ nano-silver composite material is obtained, and the nano-gold is prepared under the heating condition, and the xylan/ nano-gold composite material is obtained. The preparation conditions of the nano silver are as follows: the microwave heating temperature is 60 to 70 DEG C, the microwave power is 800W, the microwave time is 30 minutes, the ammonia concentration is 2 percent, the proportion of the xylan and the AgNO3 is 50 mg to 0.13 mmol, the nano silver generated under the condition is wrapped by the xylan, the dispersion is uniform, and the particle size distribution is 20 to 35 nm; The optimum preparation conditions of the nano-gold are as follows: the mass ratio of the xylan and the HAuCl4-4H2O is 0.15 g:15 mg, the reaction temperature is 80 DEG C, the reaction time is 40 min, the particle size of the nano-gold obtained under the condition is 10-30 nm, and the nano-gold has a narrow particle size distribution. The reaction mechanism of the obtained xylan green synthetic nano-noble metal is that the reductive end group of the xylan can reduce the noble metal ions into a noble metal simple substance, and the noble metal ion is also oxidized into a metal base, in which the main chain of the xylan is only slightly hydrolyzed, but the side chain is partially shed; And finally, the nano-particles are formed, and the hydroxyl groups in the xylan have high electronegativity and can be coated on the surface of the nano-noble metal particles to be a stabilizer. in addition, that xylan/ nano-silver and the xylan/ nano-gold composite material can carry out high-sensitivity and specific detection on the mercury ion and the cysteine, wherein the minimum detection limit (LOD) of the xylan/ nano-silver composite material to the mercury ion can reach 4.6 n-M, The detection limit of cysteine (LOD) was 0.57. m u.M, and cysteine was also detected in the plasma environment. on the one hand, the invention provides a new way for green synthesis of the nano-noble metal, and on the other hand, the obtained nano-noble metal is used for the detection of the mercury ions and the cysteine, The synthesis of xylan-click-chitosan quaternary salt-salt polymer (Xylan-click-QCS) and its application in the preparation of nano-metal materials are based on the above research. in the present study, first, the bromopropyne and the xylan are reacted to form the propargyl-xylan, and the chitosan quaternary salt is generated by the chitosan quaternary salt, and the 6-position hydroxyl group is replaced by the toluene sulfo-base and reacts with the sodium azide to generate the azido chitosan quaternary salt, Xylan-click-QCS is then chemically synthesized under the catalysis of copper (I). then the nano-silver and the nano-gold are prepared by using the Xylan-click-QCS, And the three-ring ring in the chemical product can not only provide the original site for the growth of the nano-noble metal particles, but also can passivate the surface of the generated nano metal particles to make the surface of the nano metal particle stable. wherein the generated nano-silver particle size distribution has two ranges of 10-20 nm and 2-5 nm, which indicates that the nano-silver cluster is formed in addition to the nano-particles, and the application range of the product can be greatly expanded after the nano-silver clusters are separated; and the generated nano-silver particle size distribution is 20-30 nm, Compared with the nano-gold synthesized by the xylan, the particle size distribution is more uniform.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O636.1;TB332
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