【作者】 王玉强；

【导师】 陈春海；

【作者基本信息】 吉林大学 ， 化学工程（专业学位）， 2021， 硕士

【摘要】 形状记忆聚合物作为一种功能材料,自20世纪80年代起就备受关注,迅猛发展至今。其在航空航天、医疗器械、智能制造、微电子领域等多个领域有着重要的应用价值,是现在以及未来所亟需的智能材料。聚酰亚胺因其具有优异的热稳定性、耐腐蚀性、耐辐射性、优异的机械性能以及高的玻璃化转变温度受到了科研学者的广泛关注。然而,聚酰亚胺作为综合性能优异的高分子材料在形状记忆方面的研究还不是很多。而且,对于聚酰亚胺的形状记忆功能研究主要集中在双重形状记忆效应方面,对于多重形状记忆效应研究较少,且聚酰亚胺的多重形状记忆效应多为利用其较宽的玻璃化转变温度获得。本文旨在设计合成新型聚酰亚胺,在保持其优异性能的同时,通过对其分子链段结构进行调控,制备得到具有优异形状记忆性能的聚酰亚胺材料。首先,本文根据形状记忆聚合物分子链段刚柔相济的特点,设计合成了一种含有多个甲基结构的二胺单体(BCPP),将其与含有三氟甲基结构的二酐单体(6FDA)进行聚合,并采用具有空间立体结构的多元氨基交联剂(OAPS)进行交联,从而得到一系列低交联密度的聚酰亚胺。对于含有交联结构的聚酰亚胺的结构和性能进行了表征和研究,结果表明不同交联剂含量的聚酰亚胺均具有优异的力学性能和热性能。随着交联剂含量的增加,交联剂中硅氧烷结构团聚现象逐渐明显,聚合物的玻璃化转变温度呈现先升高后降低的趋势,聚合物的形状记忆固定率和回复率呈现先增加后降低的趋势,形状记忆回复率在添加一定含量交联剂后得到大幅提升。OAPS含量为2%的PI薄膜在弯折-回复中表现出良好的形状记忆回复率,表明交联结构的引入提高了材料的形状回复率。进而,为了解决纯PI在多重形状记忆过程中固定率低的问题。设计合成了一种含有酰亚胺结构的二酸单体,将其与长链二胺单体进行聚合,得到聚酰胺-酰亚胺。同时,利用该二酸单体前驱体二酐与同种长链二胺单体聚合,得到主链结构相似的聚酰亚胺。并通过溶液共混的方法对两种聚合物进行不同比例混合,得到一系列共混聚合物薄膜,并对其结构和性能进行了表征和研究。结果表明,两种聚合物均具有优异的机械性能和热性能,五种共混聚合物薄膜均表现出两个玻璃化转变温度。随着薄膜中聚酰亚胺含量的增加,材料的第一玻璃化转变温度强度逐渐下降,第二玻璃化转变温度强度逐渐上升;材料相态经历了海岛结构-双连续结构-海岛结构的转变。其中PAI质量分数为30%,PI质量分数为70%的复合薄膜性能最好,表现出良好的三重形状记忆循环稳定性,经过4次循环后,其固定率与回复率均超过90%。更多还原

【Abstract】 Shape memory polymer(SMP),as a functional material,has been widely studied since the 1980 s and has developed rapidly.Until now,it has important application value in aerospace,medical devices,intelligent manufacturing,microelectronics and other fields,and it is also a much-needed intelligent material for the present and the future.Polyimide has been widely concerned by researchers because of its excellent thermal stability,corrosion resistance,radiation resistance,excellent mechanical properties and high glass transition temperature.However,polyimides were not well studied in shape memory as a polymeric material with excellent overall performance.Moreover,the study of the shape memory function of polyimide mainly focuses on the dual-shaped memory effect.There were a few studies on multi-shape memory polyimide,and the multi-shaped memory effect of polyimide was mostly obtained by manufacturing a wider glass transition temperature.The purpose of this paper was to design and synthesize a new type of polyimide by regulating the structure of its molecular chain segment,meanwhile to prepare high performance polyimide with excellent shape memory behavior.First of all,according to the traditional shape memory polymer molecular chain segment combines hardness with softness,a diamine monomer containing multiple methyl structure was designed and synthesized.Then,it was polymerized with a dihydride monomer containing a trifluoromethyl structure,and crosslinked by a multiamino crosslinker with a cage structure,resulting in a series of low crosslink density polyimides.The structure and performance of polyimide containing crosslinking structure were studied,and the results showed that all polyimides with crosslinker had excellent mechanical and thermal properties.With the increase of crosslinker content,the glass transition temperature of polyimide showed the trend of increasing and then decreasing.The shape memory recovery rate was greatly increased after the addition of a certain amount of crosslinker.PI-2 showed great shape memory recovery rate in bending-recoverying test,indicating that the introduction of crosslinking structure improved the shape recovery rate of the material.Further,in order to solve the problem of low fixed rate of pure polyimide in multishape memory.This section designed and synthesized a di-acide monomer containing the imide structure.Then,it was polymerized with a long chain diamine monomer to obtained poly(amide-imide).At the same time,the polymerization of the precursor monomer dihydride with the same kind of long-chain diamine monomer was carried out to obtain polyimide with similar structure.By mixed the two polymers in different ratios,a series of mixed polymer films were obtained and their structure and properties were studied.Both polymers had excellent mechanical and thermal properties,and the five mixed polymer films exhibit two glass transition temperatures.With the increase of polyimide content in the matrix,the temperature strength of the first glass transition of the material decreased gradually,and the temperature strength of the second glass transition gradually increased.The material phase state had undergone the transformation of island structure-double continuous structure-island structure.The composite film with PAI mass fraction of 30% and PI mass fraction of 70% has the best performance,showing good triple shape memory cycle stability.After four cycles,the retention rate and recovery rate are more than 90%.更多还原