A Wet-Spinning Fiber Process Providing Controlled Morphology of the Wet-Spun Fiber

The present invention employs a fluorinated PI (polyimide) in a wet spinning fiber process. The fluorinated PI was chosen because of its desirable properties for electronic applications, and the present invention is not limited to this type of fiber. The solvent used for spinning of the fiber (the solvent in the Spinning dope) requires a material which can form solutions with the polyimide. Examples include ethyl acetate, methylene chloride, and dimethylacetamide (DMAc). These solvents were chosen to reflect a large range of both solubility parameters and miscibility with water. For the coagulation bath utilized in the wet spinning process of the present invention, the coagulation baths range from 100% coagulant to 40% water which is equivalent to a mole fraction range between 1.0 and 0.2-0.3, with the lower limit dependent upon the non solvent used. The coagulant chosen was ethanol or methanol. The advantage of the present invention is that the internal morphology of the wet spun fibers can be controlled by varying the rate of polymer coagulation through adjustments in non-solvent/solvent miscibility and precipitation strength of the coagulation bath.