聚乙烯醇基互穿网络复合材料的微波响应型形状记忆性能

发布时间：2018-08-24 19:52

【摘要】：形状记忆材料是20世纪80年代以来不断发展起来的一类可对外界环境刺激做出响应的智能高分子材料。它以质轻、易加工、形变量大、记忆效应显著等优点被广泛应用于机械系统和医疗器械等领域。近年来,研究者不断在探索可使形状记忆材料发生形变回复的多种驱动方式,并取得了很好的研究成果。然而,尽管目前形状记忆聚合物的驱动方式已实现多样化,但相应的研究还没有扩展到微波这种高效、快速、具有潜力的刺激方式。本文结合微波的热效应和形状记忆原理,分别将微波吸收介质无机纳米颗粒碳化硅(SiC)和离子液体聚合物引入到PVA基体中,构筑基于聚乙烯醇体系的互穿聚合物网络结构,制备具有微波响应型形状记忆功能的SiC/聚乙烯醇/聚丙烯酸互穿网络无机/有机复合的材料、聚离子液体/聚乙烯醇互穿网络有机/有机复合的材料。微波响应型形状记忆SiC/聚乙烯醇/聚丙烯酸互穿网络无机/有机复合材料是以聚丙烯酸(PAA)为交联结构、PVA互穿在交联网络结构中,并将无机粒子SiC作为微波吸收介质复合形成微波驱动下具有良好的形状记忆特性智能高分子复合材料。其基本原理是利用分散在聚乙烯醇基体中的SiC在交变电场下的介电性能吸收微波产生热量,该热量可以作为聚合物发生形变回复所需要的能量来实现形状记忆效应。与上述SiC/聚乙烯醇/聚丙烯酸互穿网络形状记忆性能聚合材料类似,当前大多数功能性复合材料都是靠添加功能性无机粒子来实现复合材料的功能化的,这在一定程度上存在无机填料与聚合物相容性不好、体系不稳定等问题。因此本文在前一阶段的工作基础上提出是否可以选择一种有机的甚至是聚合物材料作为微波吸收介质来实现聚合物互穿网络的形状记忆效应。考虑到离子液体常被用作微波辅助合成中的反应介质以及离子液体在微波场下的极强吸收能力,于是我们想是否可以将离子液体引入到聚合物结构当中,实现聚合物复合材料的微波响应型形状记忆行为。因此本论文第二阶段的工作是研究微波响应型形状记忆聚离子液体/聚乙烯醇互穿网络有机/有机复合材料。该体系中我们合成了功能性苯乙烯基咪唑离子液体单体,再将单体在PVA溶液中进行原位聚合形成聚苯乙烯基咪唑/聚乙烯醇复合材料。在聚乙烯醇中引入离子液体聚合物作为传热介质来实现材料的形状记忆效应,这一想法为本课题的创新之处。此外考虑到目前半互穿(Semi-interpenetrating networks, SIPNs)或互穿(Interpenetrating networks, IPNs)网络聚合物在形状记忆方面研究的不足,因此本文研究可对微波辐射作出回复响应的形状记忆聚乙烯醇互穿网络复合材料,为探索IPNs体系结构与性能之间的关系和扩大形状记忆驱动力方面提供一定的理论基础。本课题选择以微波这种高效、省时、加热均匀的清洁能源作为驱动力,是因为尽管当前国内外学者开始采用红外、光、电磁场等几种特殊的能源作为形变回复的间接驱动力,但仍存在回复过程中受热不均、回复率低、响应时间长等问题。微波驱动是利用材料内部介电损耗系数较大的偶极子或离子基团随微波高频交变电场的作用,在材料内部摩擦产生热量,从而提供形变回复所需能量。微波这种非接触加热方式有别于传统直接加热的传导方式,加热效率高、无需预热,且可实现远程控制,因此,本文提出利用微波作为形变回复新的驱动力在形状记忆材料领域具有重要的科学意义。总之,PVA体系的形状记忆复合材料是一种新型的高分子材料。本文将微波热效应和聚合物形状记忆效应相结合,利用微波间接加热的特点,设计构建以SiC和聚离子液体为微波吸收介质的具有不同结构体系形状记忆复合材料,不仅充分利用了所选材料各自优良的性能,进一步拓宽聚乙烯醇的应用领域,同时还扩大了形状记忆材料的研究范围。对于某些生物医疗元件需要借助外部热源刺激才能发挥形状记忆的特性材料来说,开发这种高效省时、无二次污染、可远程操控的微波响应型形状记忆智能材料具有十分重要的科学意义。
[Abstract]:Shape memory materials (SMMs) are a class of smart polymer materials that can respond to environmental stimuli. They are widely used in mechanical systems and medical devices for their light weight, easy processing, large deformation and significant memory effects. In recent years, researchers have been exploring ways to make shape memory possible. However, although the driving methods of shape memory polymers have been diversified, the corresponding research has not been extended to microwave, which is an efficient, rapid and potential stimulating method. Inorganic nanoparticles SiC and ionic liquid polymer were introduced into PVA matrix to construct interpenetrating polymer network structure based on polyvinyl alcohol system. SiC/polyvinyl alcohol/polyacrylic acid interpenetrating network inorganic/organic composite material with microwave-responsive shape memory function was prepared. Microwave-responsive shape memory SiC/PVA/PAA interpenetrating network inorganic/organic composites are crosslinked by polyacrylic acid (PAA), PVA interpenetrating in the crosslinked network structure, and inorganic particles SiC as microwave absorbing medium are combined to form microwave-driven composites. The basic principle of smart polymer composites with good shape memory properties is to use the dielectric properties of SiC dispersed in polyvinyl alcohol matrix to absorb the heat generated by microwave under alternating electric field. The heat can be used as the energy needed for deformation recovery of polymers to achieve shape memory effect. Most of the functional composites are functionalized by adding functional inorganic particles. To a certain extent, the compatibility between inorganic fillers and polymers is poor and the system is unstable. The shape memory effect of interpenetrating polymer networks can be realized by choosing an organic or even a polymer material as a microwave absorbing medium. Considering that ionic liquids are often used as a reaction medium in microwave-assisted synthesis and the strong absorption ability of ionic liquids in microwave field, we wonder whether ionic liquids can be separated. Subliquids are introduced into polymer structures to realize the microwave-responsive shape memory behavior of polymer composites. Therefore, the second stage of this paper is to study the microwave-responsive shape memory polyionic liquid/polyvinyl alcohol interpenetrating network organic/organic composites. Polystyrene-based imidazole/polyvinyl alcohol composites were prepared by in-situ polymerization of monomers in PVA solution with sub-liquid monomers. The introduction of ionic liquid polymers into polyvinyl alcohol as heat transfer media to achieve shape memory effect was an innovation of this subject. In addition, the current Semi-interpenetration (Semi-interpenetration) was also considered. Shape memory polyvinyl alcohol interpenetrating network composites, which can respond to microwave radiation, are studied in order to explore the relationship between the structure and properties of IPNs and to expand shape memory drive. This topic chooses microwave as the driving force, which is a kind of high-efficient, time-saving and even-heated clean energy, because although the scholars at home and abroad begin to use infrared, light, electromagnetic fields and other special energy as the indirect driving force of deformation recovery, there is still uneven heating during the recovery process. Microwave driving is a kind of non-contact heating method which is different from traditional direct heating method. In short, the shape memory composites of PVA system are a new type of polymer materials. In this paper, the microwave thermal effect and polymer shape are recorded. Combining memory effect with indirect microwave heating, the shape memory composites with different structure systems using SiC and polyionic liquids as microwave absorbing media were designed and constructed, which not only made full use of the excellent properties of the selected materials, but also widened the application fields of polyvinyl alcohol. Scope of research. It is of great scientific significance to develop this kind of smart material with high efficiency, time-saving, no secondary pollution, and remote manipulation for some biomedical devices which need external heat source stimulation to display shape memory properties.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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