Pyromellitic dianhydride oxydianiline

Abstract—The adhesion of pyromellitic dianhydride-oxydianiline (PMDA-ODA) polyimide to fluorine-contaminated silicon dioxide (F-SiO,) with y-aminopropyllriethoxysilane (APS) adhesion promoter has been studied as a function of the peel ambient humidity. The peel strength was not affected by the change in peel ambient relative humidity (RH) from 11-17% to 35-60% when APS was used at the interface. Without APS, the adhesion degraded significantly with this change in RH. It was found that although the dip application of APS caused the removal of about 80% of the initial atomic percentage of fluorine on the surface, it could not be totally removed even after several days in water at elevated temperature. 

Abstract—The effects of both y-aminopropyltriethoxysilane (APS) and elevated temperature and humidity (T H) exposure on the adhesion of pyromellitic dianhydride-oxydianiline polyimide to SiO , AkOi, and MgO were studied using XPS, SEM, and peel test. Adhesion and T H stability of PMDA-ODA on Si02 is significantly improved when APS is used at the interface, while no significant improvement is observed for AkO, or MgO. XPS analysis of the surfaces showed no retention of APS on AkO, or MgO, while Si02 did retain APS, as is expected. The APS retention is affected by surface treatment of the oxide prior to APS application. 

Adhesion of polyimides to inorganic substrates is of great importance to the microelectronics industry [1, 2]. The polyimide films are deposited most often by spin coating the polyamic acid (PAA) usually from a TV-methylpyrrolidone (NMP) solution onto the substrate surface followed by thermal imidization at temperatures up to 400<>C. The most studied polyimide is the pyromellitic dianhydride-oxydianiline (PMDA-ODA), which exhibits excellent mechanical and dielectric properties, but not so good adhesion characteristics. The latter has been generally overcome by application of an adhesion promoter, such as y-aminopropyltriethoxysilane [3-7]. The reactions of APS (coated from water solution) with the silicon dioxide surface as well as with polyamic acid have been well characterized by Linde and Gleason [4] however, we do not have such detailed information available on APS interaction with other ceramic surfaces. 

Polyimide surface modification by a wet chemical process is described. Poly(pyromellitic dianhydride-oxydianiline) (PMDA-ODA) and poly(bisphenyl dianhydride-para-phenylenediamine) (BPDA-PDA) polyimide film surfaces are initially modified with KOH aqueous solution. These modified surfaces are further treated with aqueous HC1 solution to protonate the ionic molecules. Modified surfaces are identified with X-ray photoelectron spectroscopy (XPS), external reflectance infrared (ER IR) spectroscopy, gravimetric analysis, contact angle and thickness measurement. Initial reaction with KOH transforms the polyimide surface to a potassium polyamate surface. The reaction of the polyamate surface with HC1 yields a polyamic acid surface. Upon curing the modified surface, the starting polyimide surface is produced. The depth of modification, which is measured by a method using an absorbance-thickness relationship established with ellipsometry and ER IR, is controlled by the KOH reaction temperature and the reaction time. Surface topography and film thickness can be maintained while a strong polyimide-polyimide adhesion is achieved. Relationship between surface structure and adhesion is discussed. 

Figure 3.1 Photographs of a piece of the fluorinated polyimide film (89 urn thick) (a) and a piece of the Kapton (pyromellitic dianhydride-oxydianiline-based polyimide) film (90 m thick) (b). Reproduced with permission from Ref. [106].

Creep rate spectroscopy technique turned out to be very useful for comparative estimation high-temperature performance of such valuable polymers with increased chain rigidity such as PI. The bulk of commercial PI materials rely on solvent-based fabrication techniques. However, parts and shapes, formed from dry PI resin such as pyromellitic dianhydride-oxydianiline (PMDA-ODA), have been commercially available in the last few decades from Du Pont (Vespel ). Due to their excellent temperature (up to 300-350°C), mechanical, solvent and wear resistances, these parts have achieved wide acceptance in different demanding technical applications under extremely high temperatures. 

The interactions between metals and polymers are good examples of the applications of the HSAB principle to solids. When Cr is deposited on pyromellitic dianhydride oxydianiline polyimide (PMDA-ODA P/), there appears to be some chemical bonding between Cr and PI, In this case, Cr is a "soft" acid, and P/ is "hard base. How can the bonding take place According to Ho et al. indeed the reaction does not proceed in the... 

Hedrick et al. reported imide aryl ether ketone segmented block copolymers.228 The block copolymers were prepared via a two-step process. Both a bisphenol-A-based amorphous block and a semicrystalline block were prepared from a soluble and amorphous ketimine precursor. The blocks of poly(arylene ether ether ketone) oligomers with Mn range of 6000-12,000 g/mol were coreacted with 4,4,-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) diethyl ester diacyl chloride in NMP in the presence of A - me thy 1 morphi 1 i nc. Clear films with high moduli by solution casting and followed by curing were obtained. Multiphase morphologies were observed in both cases. 

The kinetics of PAA, synthesized from 4,4 -oxydianiline and pyromellitic dianhydride, solid-state imidization both in filler absence and with addition of 2 phr Na+-montmorillonite was studied [1], The nanofiller was treated by solution of P-phenylenediamine in HC1 and then washed by de-ionized water to ensure a complete removal of chloride ions. The conversion (imidization) degree Q was determined as a function of reaction duration t with the aid of Fourier transformation of IR-spectra bands 726 and 1014 cm 1. The samples for FTIR study were obtained by spin-coating of PAA/Na+-montmorillonite mixture solution in N,N-dimethylacetamide on KBr disks, which then were dried in vacuum for 48 h at 303 K. It was shown, that the used in paper [1] method gives exfoliated nanocomposites. The other details of nanocomposites polyimid/Na+-montmorillonite synthesis and study in paper [1] were adduced. The solid-state imidization process was made at four temperatures 7) 423, 473, 503 and 523 K. 

Further work in this area is underway employing polyamic acid systems which are known to produce higher viscosity solutions (e.g. polyimides derived from 4,4 -oxydianiline and either BTDA or pyromellitic dianhydride). This is being carried out in the belief that higher viscosity solutions will give rise to higher quality, less brittle films and will, thereby, enable a broader spectrum of metal systems to be studied regarding the adhesive and electrical conductance properties of metal ion filled polyimides. 

I. poly(amide-acid) [(pyromellitic dianhydride) -a/i-(4,4 -oxydianiline)] (Both carboxy groups result from the polymerization reaction.)... 

The polyimide is formed by the thermal polycyclocondensation of the poly(amide acid). For this purpose, 5 ml of poly(amide acid) solution are placed on a watch glass (diameter 10 cm) and kept in a vacuum oven at 50 °C for 24 h.The solvent evaporates and at the same time cyclization to the polyimide takes place the resulting film is insoluble in dimethylformamide.The formation of the polyimide can be followed by IR spectroscopy the NH-band at 3250 cm disappears while imide bands appear at 1775 and 720 cm" Once the initial drying process has raised the solid content to 65-75%, the polyimide formation can be accelerated by heating the poly(amide acid) film to 300 °C in a vacuum oven for about 45 min.The polyimide made from pyromellitic dianhydride and 4,4 -oxydianiline exhibits long-term stability in air above 200 °C. 

Aromatic polyimides have excellent thermal stability in addition to their good electrical properties, light weight, flexibility, and easy processability. The first aromatic polyimide film (Kapton, produced by DuPont) was commercialized in the 1960s and has been developed for various aerospace applications. The structure of a typical polyimide PMDA/ODA prepared from pyromellitic dianhydride (PMDA) and 4,4 -oxydianiline (ODA), which has the same structure as Kapton, is shown in (1). Aromatic polyimides have excellent thermal stability because they consist of aromatic and imide rings. 

An all aromatic polyetherimide is made by Du Pont from reaction of pyromellitic dianhydride and 4,4,-oxydianiline and is sold as Kapton. It possesses excellent thermal stability, mechanical characteristics, and electrical properties, as indicated in Table 3. The high heat-deflection temperature of the resin limits its processibility. Kapton is available as general-purpose film and used in applications such as washers and gaskets. Often the resin is not used directly rather, the more tractable polyamide acid intermediate is applied in solution to a surface and then is thermally imidized as the solvent evaporates. 

The two-step poly(amic acid) process is the most commonly practiced procedure. In this process, a dianhydride and a diamine react at ambient temperature in a dipolar aprotic solvent such as N,N- dimethyl acetamide [127-19-5] (DMAc) or N-methylpyrrolidinone [872-50 4] (NMP) to form apoly(amic acid), which is then cyclized into the polyimide product. The reaction of pyromellitic dianhydride [26265-89 4] (PMDA) and 4,4 -oxydianiline [101-80-4] (ODA) proceeds rapidly at room temperature to form a viscous solution of poly(amic acid) (5), which is an ortho-carboxylated aromatic polyamide. 

However, a second component shifted to higher binding energy was observed for thin films of the compound adsorbed onto aluminum that had been cleaned by ion bombardment and then exposed to oxygen. Finally, Linde [18] has suggested that polyamic acids of pyromellitic dianhydride and oxydianiline do not react with films formed by y-APS adsorbed onto metal substrates such as aluminum and chromium because the silane is adsorbed through the amino groups. 

Polyimides have excellent dielectric strength and a low dielectric constant, but in certain electrolyte solutions they can electrochemically transport electronic and ionic charge. Haushalter and Krause (5) first reported that Kapton polyimide films derived from 1,2,4,5-pyromellitic dianhydride (PMDA) and 4,4 -oxydianiline (ODA) undergo reversible reduction/oxidation (redox) reactions in electrolyte solutions. Mazur et al., (6) presented a detailed study of the electrochemical properties of chemically imidized aromatic PMDA- derived polyimides and model compounds in nonaqueous solutions. Thin films of thermally... 

One commonly used polyimide is poly(N,N -bis(phenoxyphenyl)-pyromellitimide). This may be prepared from the reaction of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) in a two step process (Figure 1). The first step involves a solution reaction forming the poly(amic acid) (PAA). After solvent removal this material can be thermally cyclized to the polyimide (PI). To improve properties, it is often annealed at temperatures up to 400° C. 

Systems that employed HREELS for interfacial-composition determinations included poly(ethylene oxide)-polystyrene diblock copolymer on Si wafers formaldehyde poly(oxymethylene) films on Cu(lOO) and Lang-muir-Blodgett films of 4,4 -oxydianiline-pyromellitic dianhydride polyimide on Au and on highly ordered pyrolytic graphite. ... 

Poly(imides) contain the group -C(0)-NH-C(0)- in their structure. Many poly(imides) with practical applications have a more complicated formula and contain oxygen atoms and aromatic rings in the backbone [1]. One example is poly(pyromellitic dianhydride-a/f-4,4 -oxydianiline) or PMDA-ODA, CAS 25038-81-7, which is obtained from pyromellitic anhydride and oxybis(benzenamine) by water elimination as follows ... 

Fluorescence spectra of polyimide as a function of thermal history for two of the most common commercially available polyimide precursors, Du Pont PI-2545 and PI-2555, were obtained. These precursors are polyamic acids formed from the polycondensation reaction of pyromellitic dianhydride (PMDA) and oxydianiline (ODA),... 

IR spectroscopy may be used to follow two reactions occurring in polyimides exposed to high temperatures and humidities hydrolysis of the imide linkages and hydrolysis of residual anhydride end groups. The hydrolytic susceptibilities of several polyimides were measured at 90°C/95% R.H. Polymers based on benzophenone tetracarboxylic acid dianhydride (with either oxydianiline or m-phenylene diamine) appeared to undergo rather rapid hydrolysis initially, but the reaction had essentially halted by the time the measured imide content had decreased by 5-6%. Polymers based on 3,3 ,4,4 -biphenyl tetracarboxylic acid dianhydride (with p-phenylene diamine) and pyromellitic dianhydride (with oxydianiline) showed no significant imide hydrolysis. In all the polymers, the anhydride was hydrolyzed quite readily. 

The polyamic acids were prepared in these laboratories using modifications of a standard preparation (7). Benzophenone tetracarboxylic acid dianhydride (BTDA), benzenetetracarboxylic acid dianhydride (pyromellitic dianhydride PMDA), oxydianiline (ODA), 1,4-phenylenediamine (PDA) and 1,3-phenylenediamine (MPDA) were all obtained from Aldrich Chemical Co. The S -biphenyl tetracarboxylic acid dianhydride (BPDA) was obtained from Ube Chemical Company. The polyamic acids were prepared in N-methylpyrrolidinone (BTDA-ODA, BTDA-MPDA and BTDA with a 1 1 molar ratio of MPDA and ODA) or dimethyl acetamide (BPDA-PDA and PMDA-ODA). 

Synthesis and Characterization of the f-Butyl Ester of the Oxydianiline—Pyromellitic Dianhydride Polyamic Acid... 

Novel f-butyl esters of oxydianiline/pyromellitic dianhydride polyamic acid were prepared in good yield. The polymers were prepared with either meta or para repeating units. The cure behavior of these f-butyl esters was studied by IR, MS and TG analysis and was compared to that of both the parent polyamic acid and its methyl ester. It was found that a rapid deprotection of the f-butyl group occurs at around 200°C with liberation of free polyamic acid. Consequently, the cure behavior at 200 C of the f-butyl ester approaches that of the parent polyamic acid. Furthermore, the isomerism of the repeating units does not appear to have any detectable effect on the cure behavior of the polymer, although, meta isomerism appears to enhance solubility of the polymer in organic solvents. 

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