Phase appearance during polymerization of fluorinated polyimide monomers and deposition into the microscopic‐scale trenches in supercritical carbon dioxide

Abstract

ABSTRACTThe phase appearance during the synthesis of fluorinated polyamic acid (PAA) from 2,2‐bis(3,4‐anhydrodicarboxyphenyl)‐hexafluoropropane (6FDA) and 2,2′‐bis(trifluoromethyl)−4,4′‐diaminobiphenyl (TFDB) in supercritical carbon dioxide (scCO2) was investigated to obtain fundamental data for the deposition of fluorinate polyimides (PI) using scCO2. All polymerizations were carried out at 30 MPa for 60 min. The experimental temperatures ranged from 50 to 70 °C, and each of the monomer concentrations ranged from 0.67 × 10−5 to 3.3 × 10−5 mol cm−3. The holding time of the transparent phases, which was the time from the beginning of the polymerization to the appearance of a turbid phase, was increased with either a decrease in the polymerization temperature or a decrease in the initial monomer concentration. The holding time of the fluorinated PAA was longer than that of the monomers of Kapton‐type PAA. The deposition of PI into the microscopic‐scale trenches that had formed on the silicon wafer was successful in scCO2. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43334.