管状形状记忆聚合物双程自组装体系制备和研究
发布时间：2018-09-03 11:36
【摘要】：形状记忆聚合物较形状记忆金属和形状记忆陶瓷具有许多突出优点,例如密度低、形状冻结率高、易制备、转变温度可调等,可降解特性更是令其在生物医疗领域具有广阔的应用前景。但形状记忆聚合物材料的固有缺陷也限制了其发展,如实验研究不系统等。软物质科学近年来得到迅速发展,其中基于膜/基结构表面失稳自组装实现复杂微结构生成,在平面制图技术、功能表面制备、柔性电子器件等领域均具有重要应用前景,近年来得到广泛关注。但目前所研究报道的膜/基结构失稳基本都是单向不可逆的,无法实现双向形状改变。结合两个领域各自的特点和遇到的问题,为此本文提出了一种双向表面形貌力学自组装功能实现方法,并开展相应的热力学实验和特征参数表征及形貌调控。 利用高临界转变温度的SMP膜和低临界转变温度的SMP基体原位复合,并冻结初始轴向压缩变形,在随后的形状恢复过程中膜/基体系发生从光滑结构到表面失稳,再恢复光滑结构的双向可逆形状记忆效应。从本质上说,膜/基体失稳是由于结构受到外界某种刺激(如温度场、电场、生物组织生长等),其表面膜和下面软基体由于变形不匹配而造成膜受压屈曲,其后进一步刺激使变形不匹配产生的残余应力得到释放从而得到变形恢复。 本文首先介绍了稳定性问题的基本概念,以最基本的圆柱模型为例,推导了膜／基结构的失稳特征的理论框架,分析了几何和材料参数对屈曲特征参数(如极限屈曲模数、临界薄膜厚度)的影响。随后进行了以SMP膜/基复合管结构材料制备、热力学实验和变形场实时检测为主,经过多种加载方式的实验研究,确定了以加入圆柱芯作为内部支撑的加载方式。经过多种荷载下的屈曲效果对比,确定出较为理想的荷载数值,获得了较好的膜/基结构屈曲效果并实现了完整的双程自组装制备过程。有限元模拟部分在现有边界条件基础上做出一定的简化,将有限元模拟与理论解的结果进行对比,定性的分析了各种几何和材料参数对屈曲形态的影响,为深入进行膜／基复合管结构屈曲行为的定量化控制提供了重要依据。 上述研究结果揭示出SMP膜／基复合管结构的双程自组装是可行的,也是可控制的。
[Abstract]:Shape memory polymers have many outstanding advantages over shape memory metals and shape memory ceramics, such as low density, high shape freezing rate, easy preparation, adjustable transition temperature, etc. The biodegradable property makes it have a broad application prospect in biomedical field. However, the inherent defects of shape memory polymer materials also limit their development, for example, the experimental study is not systematic. The science of soft matter has been developed rapidly in recent years, in which complex microstructure can be generated based on surface instability self-assembly of membrane / base structure. It has important application prospects in plane mapping, functional surface fabrication, flexible electronic devices and so on. In recent years, wide attention has been paid. However, the instability of membrane / substrate structure reported at present is basically unidirectional irreversible and can not realize bidirectional shape change. According to the characteristics of the two fields and the problems encountered, this paper proposes a method to realize the self-assembly function of bidirectional surface morphology mechanics, and carries out corresponding thermodynamic experiments, characterization of characteristic parameters and morphology regulation. The SMP film with high critical transition temperature and SMP substrate with low critical transition temperature are in situ composite, and the initial axial compression deformation is frozen. During the subsequent shape recovery process, the film / base system is unstable from smooth structure to surface. The two-way reversible shape memory effect of smooth structure is restored. Essentially, the instability of the film / matrix is due to a certain external stimulus (such as temperature field, electric field, biological tissue growth, etc.), and the film buckles under pressure due to the mismatch between the surface film and the underlying soft substrate. After further stimulation, the residual stress caused by deformation mismatch is released and the deformation recovery is obtained. In this paper, the basic concept of stability problem is first introduced. Taking the most basic cylindrical model as an example, the theoretical framework of instability characteristics of membrane / base structures is derived, and the effects of geometry and material parameters on buckling characteristic parameters, such as ultimate buckling modulus, are analyzed. Critical film thickness). Then, the SMP membrane / base composite pipe structure material was prepared, thermodynamics experiment and deformation field real time detection were mainly carried out. Through the experimental study of various loading modes, the loading mode with cylindrical core as internal support was determined. Through the comparison of buckling effects under various loads, the ideal load values are determined, and a better buckling effect of membrane / base structure is obtained, and a complete two-way self-assembly process is realized. Based on the existing boundary conditions, the finite element simulation is simplified, the results of finite element simulation and theoretical solution are compared, and the influence of various geometry and material parameters on buckling shape is analyzed qualitatively. It provides an important basis for the quantitative control of the buckling behavior of membrane / base composite pipe structures. The results show that the two-way self-assembly of SMP membrane / base composite tube is feasible and controllable.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB381
[Abstract]:Shape memory polymers have many outstanding advantages over shape memory metals and shape memory ceramics, such as low density, high shape freezing rate, easy preparation, adjustable transition temperature, etc. The biodegradable property makes it have a broad application prospect in biomedical field. However, the inherent defects of shape memory polymer materials also limit their development, for example, the experimental study is not systematic. The science of soft matter has been developed rapidly in recent years, in which complex microstructure can be generated based on surface instability self-assembly of membrane / base structure. It has important application prospects in plane mapping, functional surface fabrication, flexible electronic devices and so on. In recent years, wide attention has been paid. However, the instability of membrane / substrate structure reported at present is basically unidirectional irreversible and can not realize bidirectional shape change. According to the characteristics of the two fields and the problems encountered, this paper proposes a method to realize the self-assembly function of bidirectional surface morphology mechanics, and carries out corresponding thermodynamic experiments, characterization of characteristic parameters and morphology regulation. The SMP film with high critical transition temperature and SMP substrate with low critical transition temperature are in situ composite, and the initial axial compression deformation is frozen. During the subsequent shape recovery process, the film / base system is unstable from smooth structure to surface. The two-way reversible shape memory effect of smooth structure is restored. Essentially, the instability of the film / matrix is due to a certain external stimulus (such as temperature field, electric field, biological tissue growth, etc.), and the film buckles under pressure due to the mismatch between the surface film and the underlying soft substrate. After further stimulation, the residual stress caused by deformation mismatch is released and the deformation recovery is obtained. In this paper, the basic concept of stability problem is first introduced. Taking the most basic cylindrical model as an example, the theoretical framework of instability characteristics of membrane / base structures is derived, and the effects of geometry and material parameters on buckling characteristic parameters, such as ultimate buckling modulus, are analyzed. Critical film thickness). Then, the SMP membrane / base composite pipe structure material was prepared, thermodynamics experiment and deformation field real time detection were mainly carried out. Through the experimental study of various loading modes, the loading mode with cylindrical core as internal support was determined. Through the comparison of buckling effects under various loads, the ideal load values are determined, and a better buckling effect of membrane / base structure is obtained, and a complete two-way self-assembly process is realized. Based on the existing boundary conditions, the finite element simulation is simplified, the results of finite element simulation and theoretical solution are compared, and the influence of various geometry and material parameters on buckling shape is analyzed qualitatively. It provides an important basis for the quantitative control of the buckling behavior of membrane / base composite pipe structures. The results show that the two-way self-assembly of SMP membrane / base composite tube is feasible and controllable.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB381
【共引文献】
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