Synthesis and properties of organosoluble polyimides derived from 2,2′‐dibromo‐ and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianilines

Two new aromatic diamines, 2,2′‐dibromo‐4,4′‐oxydianiline (DB‐ODA 4 ) and 2,2′,6,6′‐tetrabromo‐4,4′‐oxydianiline (TB‐ODA 5 ), have been synthesized by oxidation, bromination, and reduction of 4,4′‐oxydianiline (4,4′‐ODA). Novel polyimides 6a–f and 7a–f were prepared by reacting DB‐ODA ( 4 ) and TB‐ODA ( 5 ) with several dianhydrides by one‐step method, respectively. The inherent viscosities of these polyimides ranged from 0.31 to 0.99 dL/g (0.5 g/dL, in NMP at 30°C). These polyimides showed enhanced solubilities compared to those derived from 4,4′‐oxydianiline and corresponding dianhydrides. Especially, polyimides 7a , derived from rigid PMDA and TB‐ODA ( 5 ) can also be soluble in THF, DMF, DMAc, DMSO, and NMP. These polyimides also exhibited good thermal stability. Their glass transition temperatures measured by thermal mechanical analysis (TMA) ranged from 251 to 328°C. When the same dianhydrides were used, polyimides 7 containing four bromide substituents had higher glass transition temperatures than polyimides 6 containing two bromide substituents. The effects of incorporating more polarizable bromides on the refractive indices of polyimides were also investigated. The average refractive indices (n_av) measured at 633 nm were from 1.6088 to 1.7072, and the in‐plane/out‐of‐plane birefringences (Δn) were from 0.0098 to 0.0445. It was found that the refractive indices are slightly higher when polyimides contain more bromides. However, this effect is not very obvious. It might be due to loose chain packing resulted from bromide substituents at the 2,2′ and 2,2′,6,6′ positions of the oxydiphenylene moieties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of organo‐soluble polyimides based on 4,4′‐diamino‐3,3‐dimethyldiphenylmethane and conventional dianhydrides

4,4′‐Diamino‐3,3′‐dimethyldiphenylmethane was used to prepare polyimides in an attempt to achieve good organo‐solubility and light color. Polyimides based on this diamine and three conventional aromatic dianhydrides were prepared by solution polycondensation followed by chemical imidization. They possess good solubility in aprotonic polar organic solvents such as N‐methyl 2‐pyrrolidone, N,N‐dimethyl acetamide, and m‐cresol. Polyimide from 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane and diphenylether‐3,3′,4,4′‐tetracarboxylic acid dianhydride is even soluble in common solvents such as tetrahydrofuran and chloroform. Polyimides exhibit high transmittance at wavelengths above 400 nm. The glass transition temperature of polyimide from 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane and pyromellitic dianhydride is 370°C, while that from 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane and diphenylether‐3,3′,4,4′‐tetracarboxylic acid dianhydride is about 260°C. The initial thermal decomposition temperatures of these polyimides are 520–540°C. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1299–1304, 1999     

Preparation and properties of novel fluorinated polyimides based on 2,2′,6,6′-tetrafluorobenzidine

Fluorinated polyimides were prepared from 2,2′,6,6′-tetrafluorobenzidine and four conventional dianhydride monomers by a solution polycondensation reaction followed by a chemical imidization. Polyimide based on 2,2′,6,6′-tetrafluorobenzidine and hexafluoroisopropylidene bis(3,4-phthalic anhydride) (6FDA) is soluble in organic solvents such as NMP, DMA, DMF, THF, chloroform, and acetone while those based on 2,2′,6,6′-tetrafluorobenzidine and pyromellitic dianhydride (PMDA), benzophenone-3,3′,4,4′-tetracarboxylic acid dianhydride (BTDA), diphenylether-3,3′,4,4′-tetracarboxylic acid dianhydride (ETDA) are not. Polyimide from 2,2′,6,6′-tetrafluorobenzidine and 6FDA possesses high optical transparency at 350–700 nm and has a in-plane refractive index of 1.558 at 632.8 nm. All polyimides exhibit glass transition temperatures above 350°C. They also possess very high thermal stability. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1605–1609, 1998     

Synthesis and properties of new aromatic polyimides based on 2,2′‐dibromo‐4,4′,5,5′‐benzophenone tetracarboxylic dianhydride

New polyimides with enhanced thermal stability and high solubility were synthesized in common organic solvents from a new dianhydride, 2,2′‐dibromo‐4,4′,5,5′‐benzophenone tetracarboxylic dianhydride (DBBTDA). DBBTDA was used as monomer to synthesize polyimides by using various aromatic diamines. The polymers were characterized by IR and NMR spectroscopy and elemental analysis. These polyimides had good inherent viscosities in N‐methyl‐2‐pyrrolidinone (NMP) and also high solubility and excellent thermo‐oxidative stability, with 5 % weight loss in the range 433 to 597 °C. Copyright © 2004 Society of Chemical Industry     

Resistive switching characteristics of polyimides derived from 2,2′‐aryl substituents tetracarboxylic dianhydrides

2,2′‐Position aryl‐substituted tetracarboxylic dianhydrides including 2,2′‐bis(biphenyl)‐4,4′,5,5′‐biphenyl tetracarboxylic dianhydride and 2,2′‐bis[4‐(naphthalen‐1‐yl)phenyl)]‐4,4′,5,5′‐biphenyl tetracarboxylic dianhydride were synthesized. A new series of aromatic polyimides (PIs) were synthesized via a two‐step procedure from 3,3′,4,4′‐biphenyl tetracarboxylic dianhydride and the newly synthesized tetracarboxylic dianhydrides monomers reacting with 2,2′‐bis[4′‐(3″,4″,5″‐trifluorophenyl)phenyl]‐4,4′‐biphenyl diamine. The resulting polymers exhibited excellent organosolubility and thermal properties associated with T_g at 264 °C and high initial thermal decomposition temperatures (T_5%) exceeding 500 °C in argon. Moreover, the fabricated sandwich structured memory devices of Al/PI‐a/ITO was determined to present a flash‐type memory behaviour, while Al/PI‐b/ITO and Al/PI‐c/ITO exhibited write‐once read‐many‐times memory capability with different threshold voltages. In addition, Al/polymer/ITO devices showed high stability under a constant stress or continuous read pulse voltage of ? 1.0 V. Copyright © 2011 Society of Chemical Industry     

Effect of monomer composition on properties of copolyimides derived from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride/4,4′‐oxydianiline/1,3‐bis (4‐aminophenoxy)benzene

A series of uncontrolled molecular weight homopolyimides and copolyimides based on 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA)/4,4′‐oxydianiline (4,4′‐ODA)/1,3‐bis(4‐aminophenoxy)benzene (TPER) were synthesized. All the polyimides displayed excellent thermal stability and mechanical properties, as evidenced by dynamic thermogravimetric analysis and tensile properties testing. A singular glass transition temperature (T_g) was found for each composite from either differential scanning calorimetry (DSC) or dynamic mechanical analysis (DMA), but the values determined from tan δ of DMA were much different from those determined from DSC and storage modulus (E′) of DMA. The Fox equation was used to estimate the random T_g values. Some composites exhibited re‐crystallization after quenching from the melt; upon heating, multi‐melting behavior was observed after isothermal crystallization at different temperatures. The equilibrium melting temperature was estimated using the Hoffman‐Weeks method. Additionally, DMA was conducted to obtain E′ and tan δ. Optical properties were strongly dependent on the monomer composition as evidenced by UV‐visible spectra. X‐ray diffraction was used to interpret the crystal structure. All the results indicated that composites with TPER composition ≥ 70% were dominated by the TPER/s‐BPDA polyimide phase, and ≤40% by the 4,4′‐ODA/s‐BPDA polyimide phase. When the ratio between the two diamines was close to 1:1, the properties of the copolyimides were very irregular, which means a complicated internal structure. Copyright © 2011 Society of Chemical Industry     

Residual stress and mechanical properties of polyimide thin films

Four different structure polyimide thin films based on 1,4‐phenylene diamine (PDA) and 4,4′‐oxydianiline (ODA) were synthesized by using two different dianhydrides, pyromellitic dianhydride (PMDA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), and their residual stress behavior and mechanical properties were investigated by using a thin film stress analyzer and nanoindentation method. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. The morphological structure of polyimide thin films was characterized by X‐ray diffraction patterns and refractive indices. The residual stress was in the range of ?5 to 38 MPa and increased in the following order: PMDA‐PDA < BPDA‐PDA < PMDA‐ODA < BPDA‐ODA. The hardness of the polyimide films increased in the following order: PMDA‐ODA < BPDA‐ODA < PMDA‐PDA < BPDA‐PDA. The PDA‐based polyimide films showed relatively lower residual stress and higher hardness than the corresponding ODA‐based polyimide films. The in‐plane orientation and molecularly ordered phase were enhanced with the increasing order as follows: PMDA‐ODA < BPDA‐ODA < BPDA‐PDA ～ PMDA‐PDA. The PDA‐based polyimides, having a rigid structure, showed relatively better‐developed morphological structure than the corresponding ODA‐based polyimides. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of 4,4′‐diaminodiphenyl ether on the structures and properties of isocyanate‐based polyimide foams

A series of thermal insulation, acoustic absorption isocyanate‐based lightweight polyimide (PI) foams with 4,4′‐diaminodiphenyl ether (ODA) units were prepared from polyaryl polymethylene isocyanate (PAPI) and the esterification solution derived from pyromellitic dianhydride (PMDA) and ODA. The structures and properties of the PI foams prepared with different molar ratio of ODA/PMDA were investigated in detail. The results show that the ODA units have great influence on the foam properties. With the increase of the ODA units, the density decreases firstly and then increases. When the molar ratio of ODA/PMDA is 3/10, the foam reaches the minimum density (13.7 kg/m³). Moreover, with increasing the ODA units, the acoustic absorption properties increase firstly and then decrease owing to the variation of the average cell diameter of the PI foams. All PI foams show excellent thermal stability, and the 5% and 10% weight loss temperature are in the range of 250–270 °C and 295–310 °C, respectively. In addition, the PI foams present low thermal conductivity and thermal diffusivity. Furthermore, the mechanical property was also evaluated and the compressive strength of the PI foams is in the range of 33.0–45.7 kPa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46029.     

Synthesis of poly(propylene glycol)‐grafted polyimide precursors and preparation of nanoporous polyimides

A novel approach to prepare a polyimide nanofoam was explored by using a polyimide precursor grafted with a labile poly(propylene glycol) (PPG) oligomer. The PPG‐grafted polyimide precursor, poly((amic acid)‐co‐(amic ester)), was synthesized via partial esterification of poly(amic acid) derived from pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) with bromo‐terminated poly(propylene glycol) in the presence of K₂CO₃ in hexamethylphosphoramide and N‐methylpyrrolidone. The precursor polymer film was spin‐coated onto a glass substrate, then imidized at 200 °C under nitrogen, and subsequently the PPG graft was decomposed by heating the film at 300 °C for 9 h in air, resulting in the PMDA/ODA polyimide nanofoam. The precursor polymers, polyimides and foamed polyimides were characterized by a variety of techniques including ¹H‐NMR spectroscopy, Fourier‐transform infrared (FT‐IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The homogeneously distributed nano‐sized pores of 20–40 nm were observed by transmission electron microscopy (TEM) of the foamed polyimide. Copyright © 2004 Society of Chemical Industry     

The pyrolysis behaviors of polyimide foam derived from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride/4,4′‐oxydianiline

The thermal stability and pyrolysis behaviors of polyimide (PI) foam derived from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA)/4,4′‐oxydianiline (4,4′‐ODA) in air and in nitrogen were studied. The decomposition products of PI foam were analyzed by thermogravimetry‐Fourier transform infrared spectroscopy (TG‐FTIR). Several integral and differential methods reported in the literatures were used in decomposition kinetics analysis of PI foam. The results indicated that the PI foam was easier to decompose in air than in nitrogen, with ～ 55% residue remaining in nitrogen versus zero in air at 800^oC. The main pyrolysis products were CO₂, CO, and H₂O in air and CO₂, CO, H₂O, and small organic molecules in nitrogen. The different dynamic methods gave similar results that the apparent activation energies, pre‐exponential factors, and reaction orders were higher in nitrogen than those in air. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of montmorillonite on thermal and moisture absorption properties of polyimide of different chemical structures

The thermal properties and the moisture absorption of three types of polyimide/montmorillonite nanocomposite were investigated: 3,3′,4,4′‐biphenyltetracarboxylic dianhydride‐4,4′‐oxydianiline (BPDA‐ODA); pyromellitic dianhydride‐ODA (PMDA‐ODA); and 3,3′,4,′‐benzophenone tetracarboxylic dianhydride‐ODA (BTDA‐ODA). The inhibition effect on in‐plane coefficients of thermal expansion (CTE) and moisture absorption of these polyimide nanocomposites by layered silicates from montmorillonite was found to decrease with the crystallinity in the pristine polyimides. The largest reduction, 30% in in‐plane CTE occurred in the case of amorphous BTDA‐ODA containing 5 wt % montmorillonite as compared with that of pure BTDA‐ODA, while the reduction in in‐plane CTE was 20% for the case of semicrystalline BPDA‐ODA. The maximum reduction in moisture absorption, 43%, also took place for the case of 3/97 ODA‐Mont/BTDA‐ODA as compared with that of pure BTDA‐ODA, whereas the semicrystalline 1/99 PPD‐Mont/BPDA‐ODA showed a 30% reduction as compared with that of pure BPDA‐ODA. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1742–1747, 2001     

Preparation and characterization of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride-pyromellitic diahydride alternating polyimides

Four kinds of 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA)-pyromelliitic dianhydride (PMDA) alternating polyimide (BTDA-PMDA API) were obtained by reacting 1 mol BTDA with 2 mol diamines to form BTDA chain-extended diamines (BTDA CED), followed by the addition of 1 mol PMDA to yield the BTDA-PMDA alternating polyamic acids (BTDA-PMDA APA), and finally by imidizing them thermally. BTDA CED were characterized by elemental analysis, infrared (IR), and ¹H-NMR spectroscopy. The structures of BTDA-PMDA APA and BTDA-PMDA API were investigated by IR and ¹H-NMR spectroscopy, and their thermal properties and interfacial tension were also studied. Furthermore, the characteristic properties of BTDA-PMDA API were compared with their corresponding homopolyimides from BTDA (BTDA HPI) and from PMDA (PMDA HPI). It was found that the alternating condensation polymerization is an effective method to modify polyimides interfacial tension with a small influence on the thermal stability. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1585–1593, 1997     

Studies on the photodegradation of polarized UV‐exposed PMDA–ODA polyimide films

Polarized Fourier transform infrared (FTIR) and ultraviolet‐visible (UV‐VIS) spectroscopy were used to investigate the photodegradation direction of polarized UV (PUV)‐irradiated polyimide (PI) films based on pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA). PI films strongly absorb below 350 nm, resulting in a photochemical reaction of the PI. PUV irradiation of the PI film caused a decrease of all existing peaks and formation of new peaks at 3258, 1748, and 1710 cm^?1 in the IR, due to degradation of the PI molecules. The preferential degradation of PI molecules parallel to the PUV irradiation direction results in the predominant orientation of the remaining PI molecules perpendicular to the PUV irradiation direction. But rubbing of the PI films induced orientation of the PI molecules parallel to the rubbing direction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3072–3077, 2002     

Synthesis and properties of novel alicyclic‐functionalized polyimides prepared from natural—(D)‐camphor

In this article, a new alicyclic‐functionalized diamine, 1,3‐bis(4‐aminophenoxymethylene)‐1,2,2‐trimethylclopentane (BAMT) was successfully synthesized starting from natural —(D)‐camphor through four reaction steps of oxidation to offer a dicaboxylic acid, reduction to offer a diol, nucleophilic substitution to give a dinitro compound and then reduction to give the final diamine. Two alicyclic‐containing polyimides were prepared by polycondensing BAMT with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 4,4′‐oxydiphthalicanhydride (ODPA), respectively. For the studies of the structure–property relationships of the polyimides, one aromatic polyimide of 4, 4′‐oxydianiline (ODA) polycondensed with ODPA was prepared in comparison. The alicyclic‐containinig polyimides PI (BPDA‐BAMT) and PI (ODPA‐BAMT) maintain good thermal properties with glass transition temperatures (T_g) of 257°C and 240°C, and temperatures at 5% weight loss (T₅) of 443°C and 436°C in nitrogen, respectively. The alicyclic polyimides exhibit tensile strengths of 91.9–133 MPa, Young's moduli of 2.75—3.24 GPa, and elongations at break of 5.6–18%. Compared with the aromatic polyimide PI (ODPA‐ODA), PI (ODPA‐BAMT) shows improved transparency with the UV‐Vis transmittance at 500 nm over 80%. In addition, PI (ODPA‐BAMT) displays better solubility than PI (ODPA‐ODA), which has been confirmed by the bigger d‐spacing value of PI (ODPA‐BAMT) than that of PI (ODPA‐ODA) calculated from the Wide‐angle X‐ray Diffraction spectra. This study indicates that the renewable forestry compound, such as natural —(D)‐camphor, could be a good origin for the structural designing and preparation of alicyclic‐containing polyimides with outstanding combined features suitable for advanced microelectronic and optoelectronic applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of poly(amic acid) and polyimide derived from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride with different diamines by microwave irradiation

Polycondensation‐type poly(amic acid) (PAA) was synthesized with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride as a dianhydride monomer and 4,4′‐diaminodiphenylmethane and 4,4′‐oxydianiline as diamine monomers under microwave irradiation in dimethylformamide. Then, PAA was used to make polyimide (PI) by imidization at a low temperature. The structure and performance of the polymers were characterized with Fourier transform infrared (FTIR), proton nuclear magnetic resonance (¹H‐NMR), viscosity, X‐ray diffraction (XRD), and thermogravimetry (TG) curve analyses. The FTIR spectra of the polymers showed characteristic peaks of PI around 1779 and 1717 cm^?1. The ¹H‐NMR spectrum of PAA indicated a singlet at 6.55 ppm assigned to ? NHCO? and a singlet at 10.27 ppm assigned to carboxylic acid protons. The XRD spectrum demonstrated that the obtained PI had a low‐order aggregation structure with a d‐spacing of 0.5453 nm. The TG results revealed that the PI was thermally stable with 10% weight loss at 565°C in an N₂ atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

The effect of molecular structure on the gas transmission rates of aromatic polyimides

A series of high-molecular weight condensation polyimides was evaluated to determine the effect of polymer molecular structure on the transmission rate of oxygen, carbon dioxide, and water vapor. The polyimide films were prepared from either 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) or pyromellitic dianhydride (PMDA) with various diamines. The study shows that molecular structure had a strong influence on gas transmission rates with results for some films varying three orders of magnitude from that of other polyimide films. In general, the BTDA series of polyimides had overall lower gas transmission rates than the PMDA-derived series. Polymers prepared with meta-oriented diamines characteristically displayed lower gas transmission than those prepared with para-oriented diamines.     

Polyimide fibers prepared by a dry‐spinning process: Enhanced mechanical properties of fibers containing biphenyl units

Polyimide (PI) fibers with enhanced mechanical properties and high thermal and dimensional stability were prepared via a two‐step dry‐spinning process through the introduction of 3,3′,4,4′‐biphenyl tetracarboxylic dianhydride (BPDA) containing biphenyl units into rigid homopolyimide of pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline. The attenuated total reflectance–Fourier transform infrared spectra results imply that the incorporated BPDA moieties accelerate the imidization process and increase the imidization degree (ID) of the precursor fibers; this was attributed to the increased molecular mobility of the polymer chains. Two‐dimensional wide‐angle X‐ray diffraction spectra indicated that the prepared PI fibers possessed a well‐defined crystal structure and polymer chains in the crystalline region were highly oriented along the fiber axis. The PI fiber, with the molar ratio of PMDA/BPDA being 7/3, showed optimum tensile strength and modulus values of 8.55 and 73.21 cN/dtex, respectively; these were attributed to the high IDs and molecular weights. Meanwhile, the PI fibers showed better dimensional stability than the commercial P84 fiber, and this is beneficial for its security applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43727.     

Novel poly(thiourea‐ether‐imide)s derived from 4,4′‐oxydiphenyl‐bis(thiourea): probing the possibility for high‐temperature applications

Our interest in the fabrication of high‐performance polyimides has led to thiourea‐substituted poly(thiourea‐ether‐imide)s (PTEIs) with good retention of thermal properties along with flame retardancy. A new aromatic monomer, 4,4′‐oxydiphenyl‐bis(thiourea) (ODPBT), was efficiently synthesized and polymerized with various dianhydrides (pyromellitic dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 4,4′‐(hexafluoroisopropylidene)diphthalic dianhydride) via two‐stage chemical imidization to fabricate a series of PTEIs. The structural characterization of ODPBT and the polymers was carried out using Fourier transform infrared, ¹H NMR and ¹³C NMR spectral techniques along with crystallinity, organosolubility, inherent viscosity and gel permeation chromatographic measurements. PTEIs bearing C?S and ? O? moieties in the backbone demonstrated an amorphous nature and were readily soluble in various amide solvents. The novel polymers had inherent viscosities of 1.16–1.23 dL g^?1 and molecular weights of ca 90 783–96 927 g mol^?1. Their thermal stability was substantiated via 10% weight loss in the temperature range 516–530 °C under inert atmosphere. The polyimides had glass transition temperatures of 260–265 °C. Incorporation of thiourea functionalities into polymer backbones is demonstrated to be an effective way to enhance their thermal properties and flame retardancy. Thus, ODPBT can be considered as an excellent candidate for use in the synthesis of high‐performance polymeric materials. Copyright © 2010 Society of Chemical Industry     

Correlation of residual stress and adhesion on copper by the effect of chemical structure of polyimides for copper‐clad laminates

BACKROUND: Polyimide films coated on copper are a potential new substrate for fabricating printed circuit boards; however, adhesion between the copper and polyimide films is often poor. The relations between residual stress and adhesion strength according to the development of molecular orientation of polyimide films with different chemical backbone structure coated on copper were studied. RESULTS: The effect of chemical structures on properties including the residual stress and the adhesion strength were widely investigated for four different polyimides. Diamine 4,4′‐oxydianiline (ODA) and dianhydrides 1,2,4,5‐benzenetetracarboxylic dianhydride (PMDA), 4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA) and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) were used to synthesize polyimide. In an attempt to quantify the interaction of thermal mismatch with the polyimide films depending on various structures, residual stress experiments between polyimide film and Cu? Si wafer were carried out over a range of 25–400 °C using in situ thin film stress analysis. A universal test machine was used to conduct 180° peel test (ASTM D903‐98) of polyimide film from cooper foil. The residual stress on Cu? Si (100) wafer decreased in the order 6FDA‐ODA > BTDA‐ODA > ODPA‐ODA > PMDA‐ODA, and the interfacial adhesion strength decreased in the order BTDA‐ODA (5 N mm^?2) > ODPA‐ODA > PMDA‐ODA > 6FDA‐ODA. The results may suggest that the morphological structure, degree of crystallinity of chain orientation and packing significantly relate to the residual stress and adhesion strength in polyimide films. Wide‐angle X‐ray diffraction was used for characterizing the molecular order and orientation and X‐ray photoelectron spectroscopy was used for the analysis of components on copper after polyimide films were detached to confirm the existence of copper oxide chemical bonding and to measure the binding energy of elements on the copper surface. CONCLUSION: In this research, it is demonstrated that BTDA‐ODA polyimide has a low residual stress to copper, good adhesion property, good thermal property and low dielectric constant. Therefore, BTDA‐ODA would be expected to be a promising candidate for a two‐layer copper‐clad laminate. Copyright © 2007 Society of Chemical Industry     

2,6‐Diamino‐4‐phenylphenol (DAPP) copolymerized polyimides: synthesis and characterization

Novel soluble copolyimides containing phenyl and hydroxyl pendant groups were synthesized from pyromellitic dianhydride (PMDA) and two diamines, 2,6‐diamino‐4‐phenylphenol (DAPP) and 4,4′‐oxydianiline (ODA), in various ratios via thermal imidization. The structures and physical properties of the copolyimides were characterized by FTIR, elemental analysis, DSC, dynamic mechanical analysis (DMA), TGA, a universal testing machine for stress–strain behaviour, and a dielectric analyzer to study the effect of DAPP on the physical properties of the modified polymers. Copolyimides containing more than 40 mol% DAPP were soluble in hot N‐methyl‐2‐pyrrolidone (NMP), dimethylacetamide (DMAc) and dimethylformamide (DMF), and possessed a high glass transition temperature (358 °C) and a high modulus (3.9 GPa). Introduction of the diamine DAPP could also reduce the dielectric constant. A segment of imide linkages could convert to benzoxazole linkages by decarboxylation at temperatures higher than 420 °C under vacuum. Although the heat‐treated polybenzoxazoles (PBOs) exhibited many good properties, they were found to be too rigid and brittle to be processable for microelectronic applications. Copyright © 2005 Society of Chemical Industry