超临界流体技术制备三维多孔支架相平衡及传质动力研究

发布时间：2018-03-29 06:17

本文选题：超临界流体　切入点：组织工程　出处：《河北科技大学》2017年硕士论文

【摘要】：组织工程近年来一直是生命科学研究的前沿课题,由于人体器官移植供源的短缺,人造组织的培养有广阔的应用前景。研究者根据超临界流体的特殊性质提出的ScCO_2诱导相分离-循环干燥法,在制备三维多孔支架过程中运用此种方法收到了不错的效果。随着研究的进展,人们发现实验结果与支架制备过程中不同厚度层中浇铸液内部ScCO_2-有机溶剂-聚合物三元相行为及ScCO_2与多孔支架内有机溶剂间的双向传质行为相关。聚合物溶液发生相分离的路径、相分离后形成的两区域的大小及组成是影响多孔支架形成和孔径及孔隙率大小的关键因素。本文通过选取模型和确定参数,利用MATLAB软件分别对ScCO_2和聚合物的三元体系相行为及ScCO_2和有机溶剂之间的双向扩散传质动力学问题进行了研究,Flory-Huggins理论是研究高分子溶液相平衡的基础理论,依据此理论,对ScCO_2诱导相分离过程中相平衡热力学行为进行了研究,构建了不同三元体系的相平衡模型。通过计算模型中不同工况下双节线、旋节线和临界点的数据,绘制出不同的三元体系相图。根据绘制出的不同三元相图,对ScCO_2/AC/PMMA和ScCO_2/CH2Cl2/PLA两种分相行为进行了分析。在工况压力增加的情况下,可导致双节线远离聚合物/溶剂轴,ScCO_2进入高聚物溶液中的量不断增加,随着温度的升高,会导致双节线向聚合物/溶剂轴靠近,ScCO_2进入溶液中的量不断变小,均相区的变化规律在ScCO_2/AC/PMMA和ScCO_2/CH2Cl2/PLA两种三元体系中相近。根据Reuvers模型,构建了适合ScCO_2诱导相分离过程的传质扩散动力学模型。针对ScCO_2/AC/PMMA三元体系,求取不同工况下的模型参数,根据相平衡过程中得到的三元相图,在相图中绘制出了不同工况的传质路径,结合实验结果分析了不同工况对孔隙状态的影响。三元体系中相互扩散系数是传质扩散过程的重要参数。随着压力的升高或温度的减小,相互扩散系数会逐渐减小。传质路径逐渐变短,三元体系达到分相的时间越短,导致多控支架的孔径变小。在制备多孔支架过程中,相平衡热力学和传质动力学两方面因素共同影响了支架孔隙形态。
[Abstract]:Tissue engineering has been a leading subject in life science research in recent years. Due to the shortage of donor sources for human organ transplantation, The culture of artificial tissue has a broad application prospect. According to the special properties of supercritical fluid, researchers proposed ScCO_2 induced phase separation and cycle drying method. The application of this method in the preparation of three-dimensional porous scaffolds has achieved good results. It has been found that the experimental results are related to the ternary phase behavior of ScCO2-organic solvent-polymer and the bidirectional mass transfer behavior between ScCO_2 and organic solvents in porous scaffolds during the preparation of scaffolds. The path of biological separation, The size and composition of the two regions formed after phase separation are the key factors affecting the formation of porous scaffolds and pore size and porosity. The phase behavior of ternary system of ScCO_2 and polymer and the bidirectional diffusion mass transfer kinetics between ScCO_2 and organic solvent were studied by MATLAB software. Flory-Huggins theory is the basic theory for studying the phase equilibrium of polymer solution. The thermodynamic behavior of phase equilibrium in the process of phase separation induced by ScCO_2 was studied, and the phase equilibrium models of different ternary systems were constructed. The data of two-nodal line, spin nodal line and critical point in the model under different operating conditions were calculated. The phase diagrams of different ternary systems are drawn. According to the different ternary phase diagrams drawn, the phase separation behaviors of ScCO_2/AC/PMMA and ScCO_2/CH2Cl2/PLA are analyzed. The amount of SCCO2 entering polymer solution increases with the increase of temperature, and the amount of bimodal line moving closer to the polymer / solvent axis into SCCO2 solution becomes smaller. The variation of homogeneous phase region is similar to that of ScCO_2/AC/PMMA and ScCO_2/CH2Cl2/PLA ternary systems. According to the Reuvers model, a mass transfer and diffusion kinetic model suitable for the ScCO_2 induced phase separation process is constructed. For the ScCO_2/AC/PMMA ternary system, the model parameters under different operating conditions are obtained. According to the ternary phase diagram obtained in the process of phase equilibrium, the mass transfer paths under different working conditions are drawn in the phase diagram. In combination with the experimental results, the influence of different working conditions on the pore state is analyzed. The interdiffusion coefficient is an important parameter in the mass transfer diffusion process in the ternary system. With the increase of the pressure or the decrease of the temperature, The mass transfer path becomes shorter, and the shorter the phase separation time of the ternary system, the smaller the pore size of the multi-controlled scaffold. Both phase equilibrium thermodynamics and mass transfer kinetics affect the pore morphology of the scaffold.
【学位授予单位】：河北科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O642.42;R318.08

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