玉米淀粉修饰及其纳米颗粒制备与表征

发布时间：2018-08-09 18:05

【摘要】：淀粉作为可生物降解和再生的高分子材料而备受关注，但原淀粉固有特性的不足限制了其应用，各种改性手段被用来对淀粉结构中活泼的多羟基官能团进行修饰，以增强淀粉材料的应用性。近年来，纳米材料的研究方兴未艾，淀粉纳米材料与其它人工高分子材料相比具有一系列的优点，尤其在药物载体和吸附剂等应用方面更表现出较强的优异性能。本文以淀粉为研究对象，从宏观和微观两个层次来研究淀粉，宏观上，，通过化学改性对淀粉进行琥珀酰基的修饰，引入阴离子基团，改善淀粉的亲水性能来获得更多优良性质，其后以淀粉和改性淀粉为原料通过沉降法制备纳米颗粒；从微观上，调控淀粉分子的凝聚态结构，探索淀粉纳米材料新的制备工艺，具体研究内容如下： 1.以淀粉为原料，琥珀酸酐为酯化剂，采用半干法工艺制备琥珀酸玉米淀粉酯，系统研究了影响淀粉酯化反应的不同因素，在单因素的基础上，利用响应面分析法，采用多元二次回归方程拟合反应因素与响应值之间的函数关系建立数学模型，并通过对响应值分析获得最优工艺参数，方差分析表明模型具有较高的拟合度。此外，还通过红外光谱(FT-IR)、X-射线衍射(XRD)、扫描电镜(SEM)等表征手段对制备的典型样品进行了结构分析。FT-IR分析表明，琥珀酰酯化反应将阴离子基团引入了淀粉分子结构中，XRD证实酯化反应主要发生在淀粉的无定形区，典型的晶体结构没有被破坏，SEM显示改性后的淀粉颗粒形貌保持完整。 2.选用DMSO为溶剂，淀粉充分溶解后，滴加到不良溶剂中利用沉淀技术制备水分散性纳米粒子，实验详细考察了良溶剂与不良溶剂的选取及它们的比例，淀粉液的浓度及其他影响制备纳米粒径的因素，并对制备的纳米颗粒在不同介质中分散性能进行了研究。通过动态光散射（DLS）、SEM、XRD等表征手段对制备的纳米颗粒进行了结构分析。结果表明：通过改变实验参数，可制备和调控尺寸为纳米级的淀粉粒子，实验发现，制备的纳米颗粒在不加分散剂的情况下，可以在较长时间内保持稳定，化学结构没有发生变化，晶体形态发生改变，颗粒形态呈球形。 3.以玉米淀粉为原料，采用水或碱水为溶剂，利用沉淀法制备淀粉纳米颗粒，当淀粉糊化液滴入不良溶剂乙醇中时，淀粉分子通过分子间或者分子内氢键相互作用重新装配聚合，形成纳米沉淀颗粒。实验考察了淀粉乳浓度、体系的pH、不良溶剂的量、碱液浓度、尿素含量、表面活性剂的用量等因素对淀粉纳米颗粒粒径的影响，并采用DLS、XRD、SEM对制备的粒子性能结构进行了分析，分析结果显示当不良溶剂中含有Tween80时，制备的淀粉纳米颗粒尺寸会随Tween80浓度增加而增大。 4.通过化学方法对淀粉进行改性，制备带有正负电荷的阳离子淀粉和阴离子淀粉，然后通过沉淀法利用已合成的改性淀粉制备淀粉纳米颗粒，研究了改性淀粉纳米颗粒的制备和结构表征。阳离子淀粉纳米粒子的δ-电位随取代度的增加而增高。电位均为正值，表明粒子表面带有正电荷，因此可用来负载或吸附负电荷分子，而阴离子淀粉制备的阴离子淀粉纳米颗粒则带有明显的负电荷，FT-IR分析表明改性淀粉化学结构均发生了变化，可在相应的区域发现改性基团的特征峰，XRD证实改性淀粉纳米粒子无晶体峰，SEM显示制备的粒子出现了一定聚集，干粉状态下颗粒聚集现象更明显。
[Abstract]:Starch has attracted much attention as a biodegradable and regenerated polymer material, but the deficiency of the intrinsic properties of the original starch restricts its application. Various modification methods are used to modify the active polyhydroxy functional groups in the starch structure in order to enhance the application of starch materials. In recent years, the research of nanomaterials is in the ascendant and the starch nanometer is in the ascendant. The material has a series of advantages compared with other artificial polymer materials, especially in the application of drug carrier and adsorbent. The starch is used as the research object. The starch is studied from the macro and microcosmic two levels. On the macroscopic, the starch is modified by the modification of the succinyl group by chemical modification. The anionic groups can improve the hydrophilic properties of starch to obtain more excellent properties. Then, the nanoparticles are prepared by sedimentation method with starch and modified starch as raw materials. From the microcosmic, the condensed structure of starch molecules is regulated and the new preparation technology of starch nanomaterials is explored. The specific contents are as follows:
1. succinic acid corn starch ester was prepared by semi dry process with starch as raw material and succinic anhydride as the esterifying agent. The different factors affecting starch esterification were studied systematically. On the basis of single factor, the response surface analysis method was used to fit the function relationship between the inverse and response values, and the mathematical model was set up by the multiple regression equation. The optimal process parameters were obtained by the analysis of the response value. The variance analysis showed that the model had a higher fitting degree. In addition, the structure analysis of the typical samples was analyzed by infrared spectroscopy (FT-IR), X- ray diffraction (XRD), scanning electron microscope (SEM) and so on. The analysis showed that the succinyl esterification reacted the anion group to the anionic group. In the molecular structure of starch, XRD confirmed that esterification mainly occurred in the amorphous region of starch, and the typical crystal structure was not destroyed. SEM showed that the morphologies of the modified starch granules remained intact.
2. when DMSO is used as solvent, after the starch is dissolved, the water dispersible nanoparticles are prepared by precipitation in the bad solvent. The selection of good solvent and bad solvent and their proportion, the concentration of starch and other effects on the preparation of nanoparticles are investigated in detail, and the prepared nanoparticles are divided into different media. The dispersive properties were studied. The structure of the prepared nanoparticles was analyzed by means of dynamic light scattering (DLS), SEM and XRD. The results showed that the nanometer sized starch particles could be prepared and regulated by changing the experimental parameters. It was found that the prepared nanoparticles could be used for a long time without the dispersing agent. The crystal morphology was changed and the particle morphology was spherical.
3. starch nanoparticles were prepared by precipitation method using corn starch as the raw material, using water or alkaline water as the solvent. When starch gelatinization solution was dripped into the bad solvent ethanol, the starch molecules were reassembled and polymerized through intermolecular or intramolecular interaction of hydrogen bonds to form nanoscale particles. The concentration of starch milk, the pH of the system, and the bad effect were investigated. The effect of the amount of solvent, the concentration of alkaline solution, the content of urea, the dosage of the surfactant and other factors on the particle size of the starch nanoparticles was investigated. The properties of the prepared particles were analyzed by DLS, XRD and SEM. The results showed that the size of the prepared starch nanoparticles would increase with the increase of Tween80 concentration when Tween80 was contained in the bad solvent.
4. the cationic starch and anionic starch with positive and negative charges were prepared by chemical method, and then the prepared starch nanoparticles were prepared by precipitation method. The preparation and structure characterization of the modified starch nanoparticles were studied. The delta potential of the cationic starch nanoparticles was increased with the increase of the degree of substitution. The potential is positive, indicating that the surface of the particle has positive charge, so it can be used to load or adsorb negative charge molecules, and the anionic starch nanoparticles prepared by anionic starch have obvious negative charge. FT-IR analysis shows that the chemical structure of the modified starch has been changed, and the characteristics of the modified group can be found in the corresponding region. XRD showed that the modified starch nanoparticles had no crystal peak, SEM showed that the prepared starch nanoparticles had some aggregation, and the aggregation phenomenon was more obvious in dry powder state.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TS236.9;TB383.1

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