IN-SITU FORMED 3-LAYER FILM BY ISOMERIZATION OF FLUORINATED POLYISOIMIDE IN POLYETHERSULFONE AS A MATRIX POLYMER

The novel three layer film comprised of a polyimide (PI)-polyether sul fone (PES)-PI structure has been developed. The film was cast from the homogeneous blend solution of polyisoimide (PII) and poly(oxy-1,4-phe nylenesulfonyl-1,4-phenylene) (PES) in N,N-dimethylacetamide (DMAc) on to a glass plate. PII was prepared by the ring-opening polyaddition o f 4,4'-hexafluoroisopropylidenebis(phthalic anhydride) (6FDA) and xafl uoroisopropylidenebis(p-phenylenoexy)dianiline (BAPF) followed by trea tment with trifluoroacetic anhydride (TEAA)-triethylamine (TEA) in N-m ethyl-2-pyrrolidone (NMP). The morphology of blend film was investigat ed by transmission electron microscopy (TEM). The formation of three L ayer film having a PI-PES-PI structure was confirmed by energy-dispers ive X-ray analyzer (EDX).