Photocrosslinkable polyimide and poly(imide siloxane) homo- and copolymers: synthesis and characterization

• Main Author: Moyer, Eric Scott
• Other Authors: Chemistry
• Format: Others
• Language: en_US
• Published: Virginia Polytechnic Institute and State University 2015
• Subjects: LD5655.V856 1989.M695; Polyimides; Siloxanes
• Online Access: http://hdl.handle.net/10919/54251

Novel, high molecular weight, high glass transition temperature, photocrosslinkable polyimide and poly(imide siloxane) homo- and segmented copolymers were prepared and characterized. The polyimides were synthesized by the classical two step method of first preparing soluble poly(amic acid) prepolymers by the reaction of various aromatic dianhydrides with aromatic diamines. The siloxane modified copolymers were synthesized by reacting single or mixed components of the aromatic dianhydrides with a mixture of aromatic amine and bis(3-aminopropyl) end blocked polydimethyl siloxane oligomers in a cosolvent system of tetrahydrofuran and N-methyl-2-pyrrolidinone. These dysfunctional aminopropyl terminated siloxane oligomers were prepared through an anionic ring opening equilibration polymerization of octamethylcyclotetrasiloxane with bis(3—aminopropyl) tetramethyldisiloxane in the presence of siloxanolate catalyst. Soluble fully imidized polyimides were obtained by use of a solution imidization procedure which utilized a cosolvent system of N-methyl-2-pyrrolidinone and N-cyclohexyl-2-pyrrolidone at temperatures of approximately 170°C. The fully imidized polyimides were soluble in a variety of solvents. The homo- and copolymers have been characterized for compositional analysis by FT-IR and proton NMR spectroscopy. All polymers were characterized for their thermal properties by differential scanning calorimetry, dynamic mechanical thermal analysis and thermogravimetric analysis. All homoand copolymers possessed excellent thermal characteristics and good mechanical properties. The photosensitive properties of the polyimide and poly(imide siloxane) homo- and copolymers were investigated at the UV wavelengths of 313nm and 365nm. The photosensitivities were found to depend on both the amount of benzylic methyl substituted diamine incorporated into the polyimide backbone, and the amount of aromatic ketone concentration. High concentrations of fluorinated (6F) dianhydride were also desirable. Incorporation of the polydimethylsiloxane segments into the polyimide decreased the optical density without decreasing the photosensitivity and therefore desirably allowed thicker films to be crosslinked at lower exposure doses. The adhesion of the siloxane modified polyimides to the silicon wafers was increased with significantly increasing siloxane content and at 20 weight percent, eliminated the need for conventional coupling agents. === Ph. D.