PMDA/ODA

Fig. 24. Numbering of the earbon and oxygen atoms in the repeat unit of PMDA/ODA polyimide. Reprodueed by permission of John Wiley and Sons from Ref. [33].

Adhesion of copper films to PMDA/ODA polyimide was determined by peel tests conducted on samples that were prepared by vapor-depositing a thin layer of copper onto the polyimide and then building the thickness of the metal layer to about 18 p,m by electrodeposition of copper. Results of the adhesion measurements correlated well with substrate pretreatment. When the substrate... 

Negative TOF-SIMS speetra of PMDA/ODA polyimide before and after plasma treatment are shown in Fig. 53. The speetra generally show inereas-ing fragmentation as a function of plasma treatment time. This tendency was especially evident for the peak at m/z = 215 (PMDA + H ). 

Fourier transform infrared (FTIR) spectroscopy is the most popular method for determining the imidization process in the solid state and identifying specific substituents on the macromolecular backbone (e.g., CN, SO3H, CO, SO2).131 A method for calculating the diermal imidization extent based on FTIR data has been reported by Pride.132 Raman spectroscopy was used on the model study of PMDA-ODA condensation, and the possible formation of an inline bond by reaction of an amino group with an imide carboxyle was evidenced.133... 

The first patent of Edwards and Robinson147 claims the condensations of pyromel-litic acid and aliphatic diamine salt to prepare polyimide. Recently, that approach has been revisited, and biphenyl tetracarboxylic and pyromellitic acids give a salt monomer by reaction with 1 mol of an aliphatic diamine (octamethylene diamine and dodecamethylene diamine). The salts were polymerized under 250 MPa at 250°C for 5 h in closed reaction vessels (Fig. 5.32) giving crystalline polymers.148 By reaction of pyromellitic tetraacid with oxydianiline, it has been possible to isolate a monomeric salt. It was polymerized under 30 MPa giving a PMDA-ODA polyimide with water elimination. 

The thermal imidization of a polyamic acid film (PMDA-ODA or BPDA-ODA) obtained by casting an NMP solution leads to an amorphous polyimide. Two different teams have shown that a polyamic acid solutions in NMP heated at 200°C for a short time (20 min) gives polyimide particles fully cyclized and highly crystalline, as shown by X-ray diffraction and solid 13C NMR spectroscopy.151152 The chemical imidization of the same solution gives only amorphous particles. The difference between the cyclization of a solution and a casted film in the same solvent is intriguing. In the case of the solution, the temperature and the heating time are lower than in the case of the casted film as a consequence, a less organized structure would be expected for the particle. 

An alternative to using van der Waals forces to organise molecules at surfaces is to covalently bond monomers. Haq and Richardson,34 for example, have attempted to develop PMDA-ODA oligomers using controlled imide coupling... 

PMDA, 20 266. See also Polymeric methylenedianiline (PMDA) PMDA-ODA, gel casting of, 20 271-272 PMDA-ODA structures, 10 214 PMDI polymeric isocyanate, 25 456, 457, 462. See also Polymeric methylene diisocyanate resins (PMDI) rigid polyurethanes from, 25 471-472 PMF/PMUF resins, 15 779 PMF resins, hardening of, 15 781 PMMA ionomer, 4DA and, 14 479 PM optimization (PMO), 15 466 PM process, 21 50 Pneumatic classification, 22 288 health and safety factors related to,... 

Figure 5.3. Structural repeat units for PMDA-ODA (a) and PMMA (b).

Fig.1 Dynamic mechanical spectra of PMDA/ODA polyimide and poly(phenylquinoxaline),...

Likewise, the mechanical properties of the copolymers were nearly identical or even somewhat enhanced towards the polyimide homopolymer in terms of the modulus and tensile strength values [44,47]. For most of the block copolymers, the elongations to break were substantially higher than that of PMDA/ODA polyimide (Table 4). The shape of the polyimide stress-strain curve is similar to that of a work-hardened metal with no distinguishable yield point... 

It is important to point out that the improvement in adhesion did not result from an increase in the solubihty of the imidized polymer containing the flexible coblock after the Tj cure cycle. In fact, the block copolymers demonstrated less than 2 % swelling (72 h) in the casting solvent, whereas PMDA/ODA polyimide homopolymer swells approximately 20-30 % (72 h). Clearly these data suggest that the improved auto-adhesion results from melt flow at 400 °C [44]. 

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