High-Resolution Profiling of the Polyimide−Polyimide Interface

Abstract

Dynamic secondary ion mass spectrometry (SIMS), nuclear reaction analysis, and neutron reflectometry were used to profile polyimide-polyimide interfaces. For interfaces between two layers of poly(4,4′-oxydiphenylene-pyromellitimide) (PMDA-ODA) polyimide it was determined that the interfacial fracture energy Gc and the interfacial width depended primarily upon the imide fraction, f, of the base layer. For f <0.9, there was a sharp interface between the deuterium-labeled poly(amic acid ethyl ester) (dPAE) and the base layer with a long low volume fraction tail of dPAE penetrating into the base layer. The volume fraction of the penetrant was limited by the imide fraction of the base layer and approached zero for f > 0.9. The PMDA-ODA/PMDA-ODA interface formed 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 the spin-casting process did not broaden significantly after annealing at 400°C. We also investigated the interface between a more flexible thermoplastic polyimide poly(4,4′-oxydiphenylene-oxydiphthalimide) (ODPA-ODA) and a fully imidized PMDA-ODA layer. The shape of the ODPA-ODA/PMDA-ODA interface was found to depend upon annealing temperature. Unannealed samples and samples annealed at 350°C could be fit with an error function, and the interfacial width was ∼50 Å. Samples annealed at 400 and 450°C were best fit by a fairly sharp interfacial profile with ODPA-ODA tails proceeding into the PMDA-ODA layer. The volume fraction of the ODPA-ODA in the PMDA-ODA depended upon the annealing temperature Tann. The Gc of the ODPA-ODA/PMDA-ODA interface appears limited by the solubility of ODPA-ODA in PMDA-ODA.

Multifunctional, Superelastic, and Lightweight MXene/Polyimide Aerogels

“…Preparation of Water‐Soluble PI Precursor : Water‐soluble PAA was synthesized using a reported method (Figure S16, Supporting Information) . Typically, the homogenous PAA solution was obtained by dispersing ODA in DMAc followed by adding a certain amount of ODPA under vigorous mechanical stirring for 1 h. The resultant solution was then transferred into deionized water and the precipitate was washed and dried at low temperature to avoid the degradation of PAA.…”

Adhesion mechanisms in the solid‐state bonding technique using submicrometer aromatic thermosetting copolyester adhesive

“…Both polyimides were partially cured at 240°C for 1 h (imidization degree is 60%). 4 As shown in Figures 19 and 20, in both cases, the interfaces involved with partially cured polyimides are much more diffuse than their fully cured versions, and considerable concentration of d-ATSP has diffused into the partially cured polyimides base layer. Table I lists the width of the four different interfaces, which indicates the use of a partially cured BPDA-PPD could improve BPDA-PPD's adhesion with ATSP.…”

“…1 Because polyimides are the most extensively used polymer in microelectronic industries, numerous studies have been conducted to solve polyimides' adhesion problems. Approaches to improve polyimides' adhesion include adding flexible structure into the polyimide backbone, 2 wet chemistry treating the surface of polyimide to reform polyamic acid, 3 partial curing 4 or solvent swelling the polyimide, 5 plasma activating the surface, 6 using Cr as adhesion promoter, 7 and applying adhesive, 8 etc. Most approaches were developed to solve specific interface problems involved with the sequential processing of polyimides.…”

Interfacial Reaction Induced Disruption and Dissolution of Dynamic Polymer Networks

“…For two linear polymers, the segmental interactions between the polymers and the molecular weight and rigidity of the two polymers dictate the extent of interfacial broadening as a function of time, which has been well‐studied and correlated with the change in adhesion. [ 33–36 ] The extent to which a linear polymer can penetrate into a chemically crosslinked network, on the other hand, essentially reduces to the swelling of a polymer network with a linear polymer chain. [ 37–39 ] Here, the network swelling will cause a stretching of the network chains, introducing an elastic retractive force that must be overcome by the osmotic force promoting mixing.…”