| Abstract
| - Dynamic secondary ion mass spectrometry (SIMS), nuclearreaction analysis, and neutronreflectometry were used to profile polyimide−polyimide interfaces.For interfaces between two layers ofpoly(4,4‘-oxydiphenylene−pyromellitimide) (PMDA−ODA) polyimideit was determined that the interfacialfracture energy Gc and the interfacial widthdepended primarily upon the imide fraction, f, of thebaselayer. For f<0.9, there was a sharp interface betweenthe deuterium-labeled poly(amic acid ethyl ester)(dPAE) and the base layer with a long low volume fraction tail of dPAEpenetrating into the base layer.The volume fraction of the penetrant was limited by the imidefraction of the base layer and approachedzero for f> 0.9. The PMDA−ODA/PMDA−ODA interfaceformed with a fully imidized base layer was∼30 Å in width, whereas that formed when f = 0.9 was∼80 Å in width. The interface formed during thespin-casting process did not broaden significantly after annealing at400 °C. We also investigated theinterface between a more flexible thermoplastic polyimidepoly(4,4‘-oxydiphenylene−oxydiphthalimide)(ODPA−ODA) and a fully imidized PMDA−ODA layer. The shape ofthe ODPA−ODA/PMDA−ODAinterface was found to depend upon annealing temperature.Unannealed samples and samples annealedat 350 °C could be fit with an error function, and the interfacialwidth was ∼50 Å. Samples annealed at400 and 450 °C were best fit by a fairly sharp interfacial profilewith ODPA−ODA tails proceeding intothe PMDA−ODA layer. The volume fraction of the ODPA−ODA in thePMDA−ODA depended upon theannealing temperature Tann. TheGc of the ODPA−ODA/PMDA−ODA interfaceappears limited by thesolubility of ODPA−ODA in PMDA−ODA.
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