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

Abstract

The phase appearance during the synthesis of fluorinated polyamic acid (PAA) from 2,2-bis(3,4-anhydrodicarboxyphenyl)-hexafluoropropane (6FDA) and 2,2 0 -bis(trifluoromethyl)24,4 0 -diaminobiphenyl (TFDB) in supercritical carbon dioxide (scCO 2 ) was investigated to obtain fundamental data for the deposition of fluorinate polyimides (PI) using scCO 2 . All polymerizations were carried out at 30 MPa for 60 min. The experimental temperatures ranged from 50 to 70 8C, and each of the monomer concentrations ranged from 0.67 3 10 25 to 3.3 3 10 25 mol cm 23. 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 scCO 2 .

New High-Performance Materials: Bio-Based, Eco-Friendly Polyimides

“…scCO2 is inert, nontoxic, nonflammable, relatively inexpensive, and, as an ambient gas, the solvent's removal after usage and depressurization is quite easy and hampers any ecological drawbacks. In some cases, the improved quality of the obtained products is an important factor in choosing supercritical liquids to the detriment of conventional organic solvents [70][71][72][73][74][75][76][77][78].…”

“…The majority of research dealing with the synthesis of PIs in scCO2 focuses on the polycondensation of common, commercial monomers. 6FDA or similar fluorinecontaining monomers are the preferred building blocks in this regard because most fluorinated polyimides seem to have a higher solubility in scCO2 [76][77][78].…”