海藻酸钙纳米胶囊的制备、表征及流变性研究

发布时间：2018-08-26 15:35

【摘要】：纳米胶囊技术是指将敏感成分用涂层或壁材材料(通常是聚合物)包埋起来用以防护他们免受周围介质的物理化学作用。它能够将液体香精包埋在胶囊或者膜内,使他们与外界环境隔绝开来,纳米胶囊技术有效地解决了液体香精的高挥发性和由氧化所引起的化学不稳定性。海藻酸钠(SA)是从天然海藻中提取的一种天然多糖,来源广泛,具有良好的生物相容性,其凝胶过程温和,使SA广泛用于制备包埋药物、蛋白与细胞的微胶囊的壁材材料。本文研究了以SA作为微胶囊化壁材,在水包油乳化体系中,通过离子聚合法制备海藻酸钙纳米胶囊(CANs)。以海藻酸钙纳米胶囊粒径(SIZE)及粒径分散系数(PDI)为考察指标,系统地对SA浓度、CaCl2的浓度、乳化剂种类、乳化剂用量、乳化方式及乳化时间、油水相比、柑桔香精添加量、氯化钙搅拌速度、油相乳液滴加速度及反应温度等制备条件进行研究分析。分别使用光散射仪(DLS)、扫描电镜(SEM)、红外光谱(FTIR).热重分析(TGA)对海藻酸钙纳米胶囊(CANs)的尺度大小.表观形态.化学分子结构、稳定性进行表征,并对海藻酸钙纳米胶囊乳液的热稳定性、放置稳定性以及流变特性进行表征。系统地对不同的海藻酸钠浓度、乳化剂浓度、乳化方式、香精添加量及反应温度下制备的海藻酸钙纳米胶囊乳液进行稳态和动态流变行为测试。实验结果表明,海藻酸钙纳米胶囊(CANs)的纳米胶囊粒径(SIZE)及粒径分散系数(PDI)受制备条件的影响很大。通过单因素平行实验得出海藻酸钙纳米胶囊的最优制备条件为：SA浓度为0.02%、氯化钙(CaCl2)浓度为0.080%、乳化剂为AE09、乳化剂用量为香精用量的1/10、乳化方式为超声乳化10min、油水相比为1：1、香精添加量为0.6%、搅拌速度为1000 r/min、海藻酸钠的滴加速度为0.5 d/s、反应温度为45℃。在最优制备条件下得到的海藻酸钙纳米胶囊经扫描电镜观察可知纳米粒外形呈不规则球形,由光散射仪测得平均粒径为110.2nm,粒径分布系数(PDI)为0.062。由壁材海藻酸钠(SA),芯材柑桔香精和海藻酸钙纳米胶囊(CANs)的红外光谱谱图可知柑桔香精已包埋在壁材内,在海藻酸钙纳米胶囊制备过程中,壁材海藻酸钠和氯化钙发生反应形成蛋格结构,促进了壁材对香精的包埋。对柑桔香精、海藻酸钙纳米胶囊和空白纳米胶囊的热重分析可知经海藻酸钠和氯化钙包封后,柑桔香精在高温下的热稳定性增强。通过测试得知海藻酸钙纳米胶囊乳液的热稳定性为98.6%,放置稳定性为94.8%,对海藻酸钙纳米胶囊乳液进行流变特性进行表征,由动态流变实验得知海藻酸钙纳米胶囊乳液的线性粘弹区为0.1%-10%,随着振荡频率逐渐增大,纳米胶囊乳液由以粘性为主转为弹性为主；由稳态流变实验得知27-40℃为样品的安全温度范围,制备的纳米胶囊乳液为非牛顿型纳米流体,在0.001-10s-1剪切速率范围内呈现出剪切变稀现象,在10-000s-1剪切速率范围内粘度基本保持不变。对不同的海藻酸钠浓度、乳化剂用量、乳化方式、香精添加量及反应温度下制备的海藻酸钙纳米胶囊乳液进行稳态和动态流变行为测试。动态模量测试结果表明,海藻酸钙纳米胶囊乳液在低频率下损耗模量高于贮存模量,黏性特征占主导。当频率增大时,贮存模量慢慢超过损耗模量,纳米胶囊乳液则表现弹性特征。不同制备条件导致制备的胶囊粒径不同,因此由粘性转为弹性的转折点频率不同且转折频率随粒径增大而降低。稳态流变测试结果表明,制备的海藻酸钙纳米胶囊乳液为非牛顿型纳米流体,纳米胶囊乳液在0.001-10s-1剪切速率范围内表现出剪切变稀现象,当剪切速率升高10-1000s-1时,粘度基本保持不变。不同制备条件导致制备的海藻酸钙胶囊粒径不同,纳米胶囊颗粒粒径越大,表观粘度越低,且表观粘度降低斜率越小。
[Abstract]:Nanocapsule technology refers to embedding sensitive components in coatings or wall materials (usually polymers) to protect them from the physical and chemical effects of the surrounding media. It can encapsulate liquid flavor in capsules or membranes and isolate them from the outside environment. Nanocapsule technology effectively solves the problem of liquid flavor. Sodium alginate (SA) is a kind of natural polysaccharide extracted from natural algae. It has a wide range of sources and good biocompatibility. Its gel process is mild, so SA is widely used in the preparation of encapsulated drugs, proteins and cell wall materials. Calcium alginate nanocapsules (CANs) were prepared by ionic polymerization in an oil-in-water emulsion system. The concentration of SA, CaCl2, types of emulsifiers, dosage of emulsifiers, emulsifying methods and emulsifying time of calcium alginate nanocapsules (SIZE) and particle size dispersion coefficient (PDI) were systematically investigated. The preparation conditions were studied by adding amount, stirring speed of calcium chloride, oil droplet acceleration and reaction temperature. DLS, SEM, FTIR and TGA were used to characterize the size of the calcium alginate nanocapsules (CANs), the apparent morphology, chemical molecular structure and stability, and also to the sea. The thermal stability, stability and rheological properties of calcium alginate nanocapsule emulsion were characterized. Steady state and dynamic rheological behavior of alginate nanocapsule emulsion prepared by different concentration of sodium alginate, emulsifier concentration, emulsification method, flavoring dosage and reaction temperature were systematically tested. Size and PDI of calcium nanocapsules (CANs) are greatly affected by preparation conditions. The optimum preparation conditions of calcium alginate nanocapsules are as follows: SA concentration is 0.02%, CaCl2 concentration is 0.080%, emulsifier is AE09, emulsifier dosage is 1/10 of essence dosage, emulsification is obtained by single factor parallel experiment. The method was ultrasonic emulsification for 10 minutes, oil-water ratio was 1:1, flavor addition was 0.6%, stirring speed was 1000r/min, sodium alginate dropping acceleration was 0.5 d/s, reaction temperature was 45 C. Under the optimum preparation conditions, calcium alginate nanocapsules showed irregular spherical shape and were measured by light scattering instrument. The average particle size was 110.2 nm, and the particle size distribution coefficient (PDI) was 0.062. The wall material sodium alginate (SA), core material citrus flavor and calcium alginate nanocapsules (CANs) were embedded in the wall material by infrared spectroscopy. During the preparation of calcium alginate nanocapsules, the wall material sodium alginate reacted with calcium chloride to form egg lattice structure. The thermogravimetric analysis of citrus flavour, calcium alginate nanocapsules and blank nanocapsules showed that the thermal stability of citrus flavors was enhanced at high temperature after being encapsulated by sodium alginate and calcium chloride. The results showed that the thermal stability of calcium alginate nanocapsule emulsion was 98.6%, and the stability was 94.8%. The rheological properties of calcium alginate nanocapsule emulsion were characterized. The dynamic rheological experiment showed that the linear viscoelastic region of calcium alginate nanocapsule emulsion was 0.1%-10%. With the increase of the oscillation frequency, the nanocapsule emulsion changed from sticky to elastic. The steady temperature rheology experiment showed that the safe temperature range of 27-40 cm was the sample. The nanocapsule emulsion prepared as a non Newtonian nanofluid showed shear thinning in the range of 0.001-10s-1 shear rate. The viscosity remained basically unchanged in the range of 10-000s-1 shear rate. Calcium alginate nanoparticles were prepared from different concentrations of sodium alginate, emulsifier dosage, flavoring dosage and reaction temperature. The dynamic modulus test results showed that the loss modulus of calcium alginate nanocapsule emulsion at low frequency was higher than that of storage modulus, and the viscosity characteristics dominated. When the frequency increased, the storage modulus slowly exceeded the loss modulus, and nano latex showed elastic characteristics. The size of the capsules is different, so the transition frequency from viscosity to elasticity is different and the turning frequency decreases with the increase of particle size. Steady state rheological test results show that the prepared alginate nanocapsule emulsion is non Newtonian nanofluid, and nanocapsule emulsion shows shear thinning in the range of 0.001-10s-1 shear rate. When the shear rate increased by 10-1000s-1, the viscosity remained unchanged. Different preparation conditions resulted in different particle sizes of calcium alginate capsules. The larger the particle size, the lower the apparent viscosity, and the smaller the slope of apparent viscosity reduction.
【学位授予单位】：上海应用技术学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1

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