| Among communication band's polymer waveguide materials, polyimide (PI) shows some of the prominent features. Because of its high glass transition temperature, low dielectric constant , and low coefficient of expansion, it has long been used in aerospace, electronics industry as high temperature insulating materials, lubrication material. As the aromatic polyimide has excellent thermal, mechanical, light and dielectric properties, it is widely used in electronics industry. Fluorinated polyimide (FPI) is expected not only has high thermal stability, low moisture absorption rate, good solubility characteristics, but also in the infrared band (in particular, 1310nm and 1550nm two communications windows) show very low absorption, shows an organic waveguide materials application potential. Compared to the linear polyimide, hyperbranched polyimide has good solubility, melt viscosity is low, capping the number of multi-group characteristics and can be modified, while hyperbranched structure can be isotropic largely reduce the material birefringence. This article is based on the above characteristics, a series of linear synthesis of hyperbranched polyimide and polyimide optical properties were studied.The first part on the base of the research of doctor Gao Hong, with a kind of fluorine-containing diamine monomer 1,4 - bis (2 - trifluoromethyl -4 - aminophenoxy) benzene (DFAPOB) and different anhydride synthesis a series of linear PI, and then to three amine fluoride monomer 1,3,5 - Tris (2 - trifluoromethyl -4 - aminophenoxy) benzene (TFAPOB) and different anhydride monomer synthesized a series of hyperbranched PI, then the optical properties of the two systems compared. Found that the linear polyimide of fluoride is higher than hyperbranched polyimide, so the refractive index of the linear polyimide is lower than the hyperbranched polyimide. Compared with the linear polyimide, hyperbranched polyimide with a loose-packed structure, resulting in the UV through of the hyperbranched polyimide is higher than the linear polyimide. In the same time, because the branching structure of hyperbranched polymer, the heat, the molecular chain movement is subject to restrictions on branching units, so that relative to the linear polyimide, hyperbranched polyimide has a higher rigidity to the structure of similar linear polyimide, the thermal diffusion coefficient is lower than the linear polyimide. The second part, from the perspective of molecular design, I designed and synthesized a new fluorine-containing 3-amine monomer 3 (3 - trifluoromethyl -4 - aminophenyl) amine (TFAPA), containing trifluoromethyl group and benzene ring structure, and a more rigid three-dimensional space of symmetric tight structure, and conducted a preliminary study of its performance. From the IR, NMR, DSC, MS and other means ,its clear that I got what I want is a new fluorinated monomers. In addition, we put it with the acid anhydride 6FDA reaction, have a kind of anhydride end-capped polymer, and conducted a preliminary study of this polymer. By NMR, we can see that compared with the deal full hyperbranched PI , polymerization of the hyperbranched PI can not 100 % , which is characteristic of hyperbranched polymers, it is difficult to achieve full hyperbranched product, to what can only say that how far we can get. From the infrared spectra, we can see the infrared characteristic absorption peaks of amino disappeared, and further proves that we get what we want anhydride capped hyperbranched polymersTo sum up, basis of the study Dr. Gao Hong, the linear polyimide as well as the hyperbranched polyimide ,optical properties of two series of polymers were compared at the same time.From the perspective of molecular design, change monomer structure, re-designed and synthesized a new 3-amine monomer, and the basic properties of the monomer has been studied at the same time .Trying to synthesize a anhydride end-capped hyperbranched polymer, and its basic performance is preliminary explorated and researched. |
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