| Polyimide(PI) film materials have been widely applied in many fields such as aviation, national defense, electronic device and optical- communication for their high tensile-strength^ high modulus and high dimensional stability . On the basis of the formers' researches, a novel approach which rely on -molecular-self-assemble and side-chain liquid crystalline (LC) in-situ self-reinforced enhancing the thermal and mechanic properties of polyimide films was firstly addressed in this paper. For this cause, two kinds of reaction route have been employed to introduce side-chain mesogenic units (MU) on the main-chain of PI, which are monomer-co-condensation route and macromolecular reaction route.In chapter two, two type of diamines with pendent hydroxyl group (2,4-diamino phenol and l,3-bis (4-amino phenoxy) -2-propanoI) and two kinds of mono-functional epoxide liquid crystal compound (MEC and MEAE) which structure and composition were determineded by elemental analysis, 'H-NMR,I3C-NMR and FTIR respectively were synthesized. By means of the conversion from pendent hydroxyl group to functional side-chain, novel liquid crystal side-chain in-situ self-reinforced polyimide films were achieved. In order to identify the ring-opening reaction between hydroxyl group and epoxide group, an analogous reaction was performed and the effect of reaction environment on conversion ratio was discussed in detail.Chapter 3 focuses on the topic of synthesis SLCPI via monomer reaction route. As one of co-condensation monomers containing mesogenic units, 3,5-diamino-benzenic-4'-diphenyl ester (DBDE) was synthesized firstly, then the SLCPI and combined LCPI were prepared from DBDE and other monomers. Considering the effect of the activity of diamines and the stereo-retard of mesogenic units on theformation of poly (amic acids), two-step feed was applied in the experiment so as to obtain high molecular weight poly (amic acids).The combination of the Computer Molecular Dynamics Simulation and the Molecular Engineering of side-chain liquid crystal polymer was expected to analogize and design the energy-minimized configuration of main-chain and mesogenic unit of polyimide, which polyimide exhibit anisotropic phase. Computer Molecular Dynamics Simulation results indicated that if the rigid mesogenic units attached on the semi-rigid main-chain without flexible spacer, relatively, the softer main-chains is favor of the anisotropic phase formation. Wide-Angle-X-ray Scattering (WAXS), DSC and Polarized Optical Microscopy were widely used to analyses the liquid crystal texture of SLCP. For SLCPI prepared via macromolecular reaction with flexible spacer and combined LCPI containing mesogenic units on both main-chain and side-chain, all exhibited smectic phase; otherwise, the SLCPI formed from the rigid biphenyl mesogenic units attached directly on the semi-rigid main-chain of PI, the main-chains have to adopt to flat configuration which main-chain vertical index vector quantity of mesogenic units so as to yield to rigid mesogenic units, exhibited nematic Nl phase. The Computer Molecular Dynamics Simulation and experimental results keep good consistence with each other.Another emphasis has laid on the investigation of crystallity of SLCPI in chapter four. Firstly, the rigidity of main-chain, the existence of flexible spacer and the type and level of mesogenic units have all influenced on the kind and formation of anisotropic phase of SLCPI; Secondly, the thermal-stability of anisotropic phase of SLCPI was mainly determined by the rigidity of main-chain and molecular weight of poly (amic acids); finally, the side-chain-orientation of SLCPI can be improved by stretching, polarizing and quenching (or annealing) at near isotropic temperature, as a result, the thermal-stability, dimensional-stability and mechanic property can be enhanced.The investigation of other properties such as mechanical property, thermal stability, solubility and dimensional stability shown that the rigidity of main-chain,the molecular weight and the lo...
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