【作者】 刘习奎；

【导师】 顾宜；

【作者基本信息】 四川大学 ， 材料学， 2003， 博士

【摘要】 近年来，随着高新技术与产业的迅猛发展，耐高温、高稳定性、加工性能优良的聚酰亚胺材料成为先进材料发展的一个重要方向，其应用广泛涉及到微电子、光电信息和膜分离等领域。在聚酰亚胺主链上引入功能性侧链，既可以改善聚合物的成型加工性能，同时又可获得特定的功能性，因此近年来聚酰亚胺的侧链改性与功能化研究成为一个研究热点。本论文正是围绕这一课题进行更为深入的研究。具体的讲，就是通过对二元胺单体的分子设计，调整取代基和柔性连接的种类，从结构上对聚酰亚胺进行改性。并按照分子设计和材料设计的要求，进一步系统地研究侧链聚酰亚胺合成与材料制备中的重要化学和物理问题：如大分子链的组成与结构控制，酰亚胺化过程中有序结构的形成与控制，侧链聚酰亚胺的相结构与相转变等。从而在更深的层次上寻求聚酰亚胺各层次结构与性能之间的关系，为聚酰亚胺的进一步高性能化和功能化打下坚实的基础，有助于开发出能更好的满足高密度电子封装、液晶显示等需求的高性能聚酰亚胺材料。 在本课题组前期合成3，5-二氨基苯甲酸[4-(苯基)苯]酯的基础上，本论文进一步设计并合成了3，5-二氨基苯甲酸{2-[4，-(苯基)苯氧基]乙基}酯，3，5-二氨基苯甲酸{6-[4’-(苯基)苯氧基)]己基}酯，以及3，5-二氨基苯甲酸{6-[’-(4”-氰基苯基)苯氧基]己基}酯等三种含联苯基团侧链的芳香族二元胺单体。通过熔点(MP)、红外光谱(FTIR)与核磁中文坟委共振氢谱(’H一NMR)等分析方法对二元胺单体的结构进行了表征，与理论的预期结构相吻合。在合成二元胺单体的基础上，通过经典的两步法工艺和一步法高温溶液酞亚胺化工艺，合成了一系列含有联苯基团侧链的均聚酞亚胺与共聚酞亚胺。对所制备的聚酞亚胺的结构进行了表征，并探讨了单体结构、反应条件以及酞亚胺化工艺对聚酞亚胺分子量与成膜性的影可句。 在上述合成工作的基础上，我们进一步通过热台偏光显微镜(P oM)和X一射线衍射(wAXD)对酞亚胺化过程中有序结构形成以及侧链的引入对聚酞亚胺的结晶性与结晶形貌的影响进行了研究。结果表明，在5℃胭in这样一个特定的连续升温条件下，BTD刀m一PDA的聚酞胺酸前体在酸亚胺化过程中会出现一种新型的负性环带球晶结构，这也是首次在聚酞亚胺体系中报道环带球晶的形成。进一步的研究表明，升温速度对于聚酞亚胺环带球晶的形貌有明显的影响，过快或者过慢的升温速率都会产生较小的、退化的环带球晶形貌。我们进一步采用单官能团的邻苯二甲酸醉为封端剂，就分子量对球晶形貌的影响也进行了研究，结果表明，当封端剂的加入量达到30%(mol)时，环带球晶形貌逐渐退化为具有之字形Maltese十字消光的球晶形貌。在观察到正常环带球晶的同时，还发现伴随有一定数量的变形环带球晶的生成，初步研究表明环带球晶的变形与样品一载玻片之间的相互作用有关。基于BTDA从PDA聚酞亚胺的球晶形貌的一个特殊之处是:在各种工艺条件下形成的球晶形貌均不是典型的Maltese十字消光结构，而是比较特殊的之字形Maltese十字消光结构，刚性主链的BTDA/MPDA聚酞亚胺表现出来的这些独特的结晶形貌值得进一步深入研究。 由于聚合物的聚集态结构与其性能之间有着非常密切的联系，因此伴随酞亚胺化过程发生的聚集态结构的变化方面的研究就显得尤为必要。因此我们进一步通过FTIR与WAXD对酞亚胺化过程与有序结构形成过程的相互关系进行了研究。在升温过程的初期，结晶过程与酞亚胺化过程基本上同时发生，但是其后，在溶剂的促进之下，整个结晶过程在短短的8分钟左右基本完成，此时X一衍射表明结晶度高达89%，而FTIR分析表明酞亚胺化程度只有27%，仍处于酞亚胺化的初期。在其后的高温处理中文摘奥过程中聚酞胺酸逐渐完成其酞亚胺化，而在此过程中，WAXD研究表明，聚酞亚胺的结晶结构与形貌均基本上保持不变。当引入联苯基团侧链以后，聚酞亚胺的结构与形貌均发生明显的改变，对基于BTDA的聚酞亚胺体系，当侧链较短时，只观察到许多细小的粒状晶体，没有形成典型的球晶形貌，而侧链最长的含有氰基联苯氧基侧链的BTD刀ODA+CN6DA聚酞亚胺在偏光下没有可见的结晶微粒出现。为了进一步研究聚酞亚胺主链结构对于酞亚胺化过程有序结构形成的影响，我们进一步研究了基于ODPA与PMDA的聚酞亚胺体系的结晶形貌，没有侧链的ODPA/MPDA聚酞亚胺在5’C/Min的升温条件下能够形成典型的放射性球晶形貌，且为负性。而当引入侧链以后，基于较柔性ODPA的侧链聚酞亚胺在偏光下均没有可见的晶粒形成。对主链较为刚性的基于PMDA的聚酞亚胺而言，有无侧链的情况下均形成大量的微小晶粒，没有观察到完整的球晶形貌的形成。 在结晶形貌研究的基础之上，我们进一步就联苯基团侧链的引入对聚酞亚胺相结构与相转变的影响进行了研究。X一射线衍射表明，在连续快速升温条件下，无侧链的聚酸亚胺均表现出非常高的结晶性，主链较为刚性的基于BTDA与PMDA的聚酞亚胺的结晶度均在90%以上。侧链的引入对于聚酞亚胺的结晶性有更多还原

【Abstract】 Polyimides are a class of high performance polymers thatare widely used as high temperature insulators, coatings, adhesives and advanced composite matrices. Nevertheless, further research is necessary to develop new polyimide systems in order to enhance the desirable properties for various high technology applications. One area that has received considerable attention is the side chain modification and functionalization of high performance polyimides. Introducing functional groups into polyimide chains as substitutes is very interesting because they can be used to impart special functionality to polyimide as well as to improve processability. Thus the synthetic chemistry and structure-properties relationship of polyimides with functional side chains is of great interest.The studies in this dissertation have focused on the synthesis, characterization and structure-properties relationship of polyimides with various side chains. These objectives were accomplished by design various novel diamines containing biphenyl mesogenic unit, then several novel polyimides were prepared by polycondensation of diamine containing pendent group with various aromatic dianhydrides. Many fundamental questions related to the synthetic chemistry and and physics were studied, such as: the methodology of introducing side chains, the control of macromolecular structure and architecture, and the formation and control of ordered structure. The knowledge get out from the research of structure-properties relationship of polyimides can make good contribution to the development of high performance polyimides. And themethodology of side chain modification and functionalization of polyimides has made the polyimides prepared have a unique combination of processability and high strength, high modulus which is presently unavailable in common polyimides.In the second chapter, a series of novel diamines containing various side chains with biphenyl groups 2-(4-phenylphenoxy) ethyl 3,5-diaminobenzoate, 6-(4-phenylphenoxy)hexyl 3,5-diaminobenzoate, 6-(4-cyano-phenylphenoxy)hexyl 3,5-diaminobenzoate were synthesized using 3,5-dinitrobenzoic acid as starting material. All the monomers and the. intermediates were characterized by melt points, Fourier transform infrared and ’H nuclear magnetic resonance spectroscopy; the results were in good agreement with the proposed structures. Based on these newly synthesized diamine monomers, a series of polyimides with various side mesogenic units were prepared through classical two-step thermal imidization process or one-step high temperature solution imidization process. The influences of monomer adding mode, the imidization condition and imidization proceed on the resulted films were studied.It has been recognized that some physical properties of polymer are largely affected by not only the chemical structures but also the aggregate structure. The chemical change during imidization has been studied by many groups, while the aggregate change has seldom been researched. Thus we deepen our work to study the morphological feature and crystalline structure development during thermal imidization. The combination of FTIR, DSC, WAXD and POM studies is carried out to provide some new insight into the ordered phase formation during imidization process. Of particular interesting is the observation of new banded spherulites in the BTDA/MPDA polyimide samples. The imidization and crystallization occurred in a similar way at the initial stage of thermal treatment. Then the crystallization reached nearly complete after 8 minutes thermal treatment, meanwhile the PAA was only partial imidized. The banded spherulitic morphology was dramatically affected by the imidization condition and the molecular weight of polyimide. Too slow or tooquick heating rate leaded to the relative small polyimide spherulites and the banded became less identifiable, while samples of lower molecular weight formed degenerated banded spherulites. X-ray diffraction revealed the highly crystalline nature of BTDA-MPDA0.95 polyimides更多还原