【作者】 刘洁宇；

【导师】 王策；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2007， 博士

【摘要】 聚酰亚胺(PI)是一类以酰亚胺环为结构特征的高性能聚合物材料,在微电子工业中得到了广泛的应用。电纺丝方法是制备聚合物超细纤维的常用方法,用电纺丝方法制备聚酰亚胺的超细纤维,以往的报道较少。本文用电纺丝方法制备了多种聚酰亚胺的超细纤维,研究了均苯型(PMDA//ODA)、联苯型(s-BPDA//ODA)和共聚型聚酰亚胺的电纺丝成纤条件,并用扫描电镜、红外光谱、TGA、DSC等进行了表征。本文还测定了多种聚酰亚胺电纺丝薄膜的介电常数,为1.4~1.9之间,远低于一般PI的介电常数(3.4左右),为研究超低介电常数聚酰亚胺开辟了一条新路。更多还原

【Abstract】 Aromatic polyimide with its special chemical structure has many advantages in terms of dielectric, thermal stability, mechanical, chemical resistance, etc, which had been widely used in electronic, automobile, space, military, bio-medical, communications, and high performance parts. Followed on Moore’s law, the speed of computer chips has doubled every 18 months, which requested a low loss and low dielectric substrates in the industry. In order to realize this goal, three methods were introduced in industry in order to achieve the low dielectric constant: (1) Using Flour substrated monomers; (2) filled in xerogels to form nanoporous film: (3) introducing low dielectric side chain such as, silicone group.In this thesis, we would like to introduce a novel way to prepare the low dielectric constant polyimide membranes through electrospinning. The major advantages of this preparation are (1) produced ultra thin (nano grade) polyimide fabric materials, (2) the non-woven formed polyimide fiber membranes has many nanoporous structures with a lager surface area, which has many potential industrial applications such as, filtration, insulation, packaging, etc., (3) achieved low dielectric constant of 1.5, which is even lower than the polyimide nanoporous film (2.5) and floured polyimide (2.8), and polyimide film (3.4).We used two-steps synthesis method to make polyimide (PI), i.e., preparation of polyimide precursor and imidization. Several polyimide precursors, i.e., polyamic acids (PAA), were prepared through the combinations of diamine monomers of ODA, p-TPEQ, and dianhydride monomers of PMDA, s-BPDA, BPADA, and ODPA. Then, electrospinning was applied to those polyimide precursors. We selected several monomer combination as standards to conduct the process study such as, PMDA//ODA (Kapton-H), s-BPDA//ODA (Upilex-R), and 90%PMDA/10% BPDA// ODA.As for spinning process condition studies, we had optimized the spinning concentration of polyamic acid as well as different co-solvent combination. We also conducted used FTIR to optimize the curing temperature of polyimide. SEM was used to analyze the morphology changes from PAA to PI. As for PMDA//ODA type polymer, its morphology almost has no changes during the imidization. This is because the polymer has a high Tg of 385oC (by DSC) and its polymer chain is very rigid. However, a polymer networks were formed after the imidization on s-BPDA//ODA polymer. This is because the polymer has a low Tg of 285oC (by DSC) and its polymer chain is more flexible comparing to PMDA//ODA based polymer. As for the 90%PMDA/10% BPDA// ODA polymer, it formed a“branched-tree truck”structure after the imidization. This is because the 10% BPDA has changed the polymer chain regularity, therefore, formed more amorphous structure.We had obtained an ultra low dielectric constant (DK) of ~1.5, which is significantly lower than the standard polyimide film (DK~3.4). This is because the ultra thin (nano grade) polyimide fabrics formed non-woven membranes created many nanoporous structures. This material should be very interested in several industrial areas such as, low loss and low DK substrates for high frequency electronic packaging; low DK substrates for IC packaging; high temperature stable with nanoporous membranes for filtration; High temperature stable with larger surface areas membranes for insulation, etc.更多还原