Biphenyltetracarboxylic Acid Dianhydride Research Articles

Synthesis and properties of modified thermoplastic polyimide films with good dielectric properties at high frequency and enhanced thermal stability via incorporation of rigid ester and biphenyl structural units

AbstractA series of ester‐ and fluoro‐containing thermoplastic polyimide (PI) films, PEsI‐1 ~ PEsI‐4 have been prepared by the two‐step thermal imidization procedure via the soluble poly(amic acid) (PEsAA) precursors from the copolymerization of four monomers, including the dianhydrides of bisphenol A dibenzoate‐3,3′,4,4′‐tetracarboxylic acid dianhydride (TMBPA) and 3,3′, 4,4′‐biphenyl tetracarboxylic acid dianhydride (BPDA) and the diamine monomers of 4‐aminophenyl‐4′‐ aminobenzoate (APAB) and 2,2′‐bis(trifluoromethyl)‐4,4′‐diamino biphenyl (TFMB) in the polar aprotic solvent of N‐methyl‐2‐pyrrolidinone (NMP). The PI films obtained from the high‐temperature dehydration of the PEsAA solutions exhibited the good thermal stabilities with the glass transition temperatures (Tg) over 269°C, the 5% weight loss temperatures (T5%) higher than 480°C, and the linear coefficients of thermal expansion (CTE) values in the range of 17.7 × 10−6/K–33.6 × 10−6/K in the temperature range of 50–250°C. Meanwhile, the PI films showed good thermoplasticity in the dynamic mechanical analysis (DMA) tests, in which the storage modulus of the PI films dropped sharply in the temperature range of glass transition of the polymers. At last, the PI films exhibited the good dielectric properties with the breakdown voltages (Vb) over 5200 V, the dielectric strength (Ds) higher than 210 V/μm, the dielectric constants (Dk) in the range of 3.26 ~ 3.32 at the frequency of 10 GHz, and the dielectric dissipation factors (Df) of 0.0038 ~ 0.0047. Compared with the commonly used PEsI‐ref film for high‐frequency flexible copper clad laminates (FCCL), the currently developed PI films exhibited the obviously increased Tg values, decreased CTE values, and comparable dielectric properties.

Porous Adsorbents Cross-Linked with Waste Polystyrene Foam and 3,3′,4,4′-Biphenyltetracarboxylic Acid Dianhydride for the Effective Removal and Enrichment of Cationic Dyes

Porous Adsorbents Cross-Linked with Waste Polystyrene Foam and 3,3′,4,4′-Biphenyltetracarboxylic Acid Dianhydride for the Effective Removal and Enrichment of Cationic Dyes

Polyimide aerogels with novel bimodal micro and nano porous structure assembly for airborne nano filtering applications.

Aerogels have presented a very high potential to be utilized as airborne nanoparticles' filtration media due to their nanoscale pore size and extremely high porosity. The filtering performance of aerogels, such as air permeability and filtration efficiency, is highly related to the configuration of aerogels' nanostructure assembly. However, as aerogel morphology is formed with respect to the intermolecular forces during the gelation stage, tailoring the aerogel nanostructure assembly is still a challenge. In this work, a novel strategy for tailoring polyimide aerogel nanostructure assembly is proposed by controlled disturbing of the intermolecular forces. From the results, the nanostructure assembly of the 4,4′-oxydianiline (ODA)–biphenyl-tetracarboxylic acid dianhydride (BPDA) polyimide aerogel is tailored to a uniform bimodal micro and nano porous structure. This was achieved by introducing the proper fraction of thermoplastic polyurethane (TPU) chains to the polyimide chains in the solution state and through a controlled process. The fabricated polyimide/TPU aerogels with bimodal morphology presented enhanced filtration performance, with 30% improved air permeability and reduced cell size of 3.51 nm over the conventional ODA–BPDA polyimide aerogels. Moreover, the fabricated bimodal aerogels present the reduced shrinkage, density, and effective thermal conductivity of 6.3% and 0.063 g cm−3, 28.7 mW m−1 K−1, respectively. Furthermore, the bimodal polyimide/TPU aerogels show the higher porosity of 96.5 vol% along with increased mechanical flexibility over the conventional polyimide aerogel with comparable backbone chemistry.

Colorless PI structure design and evaluation for achieving low CTE target

To obtain the colorless polyimide (PI) film with low coefficient of thermal expansion (CTE) and high thermal stability, the rigid biphenyltetracarboxylic acid dianhydride (BPDA) and 4,4'-(Hexafluoroisopropylidene) diphthalic anhydride (FDA) were selected and copolymerized with 2,2'-bis (trifluoromethyl)-[1,1'-biphenyl]-4,4'-diamine (TFDB). The physical properties of PIs were effectively regulated and optimized by adjusting the ratio of BPDA to FDA. When the ratio of BPDA to FDA is 6:4, the thermal imidized film (PI-6) performance is the best. It has a glass transition temperature (Tg) of 363 ℃, a 5% weight loss temperature (Td5) of 533 ℃, a CTE of 18.8 ppm/K, and a tensile strength of 140 MPa. The transmittance of PI-6 at 760 nm and 430 nm are up to 89.6% and 83.2% respectively. Further, the PI-6's precursor, PAA-6 were treated by chemical imidization. The obtained film has a transmittance of 92.6% at 760 nm, a decreased CTE of 15.5 ppm/K, and a tensile strength of 227 MPa, which is expected to be used as flexible display substrates. Finally, the effects of molecular and aggregation structure on the properties of PIs were studied.

Structure to properties relations of BPDA and PMDA backbone hybrid diamine polyimide aerogels

Due to the sensitive relations between aerogel physical, thermal, and mechanical properties, improving the polyimide aerogels performance requires understanding of their structure to properties relations, along with introducing a robust method to tailor aerogels properties to achieve the optimum performance. Given this background, this work extensively studies the structure to properties relations of pyromellitic dianhydride (PMDA) and biphenyl-tetracarboxylic acid dianhydride (BPDA) backbone polyimide aerogels at varying hybrid diamine fractions. Based on the results, combination of rigid and flexible diamine monomers at varying fractions successfully tailored the properties of the hybrid diamine polyimide aerogels. Also, physical, thermal, and mechanical properties of the two aerogel backbones presented a tendency to the hybrid diamine monomers fraction. However, the opposite trends of the two backbones suggested that, rather than the diamine or dianhydride monomers individually, their network structure and bonding nature would define the aerogel behavior. Furthermore, this work shows that the shrinkage and morphology are the two main parameters, those describe the aerogels properties. Therefore, tailoring these two parameters can provide aerogels with optimum performance. The fabricated aerogels presented wide range of properties with the maximum observed open cell content of 96.6% and compression modulus of 16.9 MPa along with the effective thermal conductivity and density as low as 32.5 mW/mK and 0.056 g/cm3, respectively.

Fine-tuning the molecular structure of binaphthalene polyimides for gas separations

A set of new stiff and contorted polyimides were prepared to systematically link polymer structure with gas separation properties. Seven novel bridged binaphthalene polyimides were synthesized for this purpose using commercial dianhydrides pyromellitic dianhydride (PMDA), biphenyl-tetracarboxylic acid dianhydride (BPDA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA). From these polyimides, freestanding membranes were prepared and tested on mixed gas CO2/CH4 and CO2/N2 separation performance. They were further characterized using WAXS and PALS and through the simulation of their free volume elements (FVEs) and gas separation properties. The binaphthalene polyimides had CO2/CH4 and CO2/N2 mixed gas selectivities of respectively 40 and 29 and mixed gas permeabilities of about 20 barrer for both gas mixtures.

Synthesis and characterization of high-temperature-resistant and optically transparent polyimide coatings for potential applications in quartz optical fibers protection

A series of optically transparent and colorless polyimide (CPI) coatings for quartz optical fibers (QOFs) protection were prepared by the copolymerization of two aromatic dianhydrides, 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) and 2,2′-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), and 2,2′-bis(trifluoromethyl)benzidine (TFMB) by a two-step polymerization procedure via the soluble poly(amic acid) (PAA) precursors followed by thermal imidization at elevated temperatures. Various QOFs with the flexible and tough CPI coatings were successfully fabricated. Scanning electron microscopy measurements revealed that the CPI coatings tightly adhered to the quartz optical fibers without adding any adhesion promoters. The CPI coatings exhibited good optical transparency with the transmittance higher than 83% at 450 nm at a thickness of 10 μm, high lightness (L* > 93), low yellow indices (b* as low as 2.66), and low turbidity (haze as low as 0.57%). In addition, the CPI coatings exhibited good thermal and dimensional stability with glass transition temperatures (Tg) higher than 349°C and coefficients of linear thermal expansion (CTE) as low as 6.8 × 10−6/K in the range of 50–300°C.

Obtainment of Aromatic Polyimide Nanofibers and Materials on Their Basis for Cell Technologies

Nanofibers with a diameter of 100–300 nm are obtained by electroformation of solutions of polyamide acid based on 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride and o-toluidine in an N,N-dimethylacetamide/ benzene solvent mixture. Thermal treatment of nanofibrous polyamide acid material leads to the formation of nanofibers of aromatic polyimide with a diameter of 100–200 nm. The temperature of the beginning of thermal decomposition of polyimide nanofibers in an argon atmosphere is 537°C. SEM images show that the material based on aromatic polyimide nanofibers preserves its elastic properties even at the temperature of liquid nitrogen. The obtained material is characterized by the absence of cytotoxicity: human fibroblasts cultivated on it are characterized by high proliferative activity.

Trisilanolphenyl-POSS nano-hybrid poly(biphenyl dianhydride-p-phenylenediamine) polyimide composite films: miscibility and structure-property relationship

A partially condensed polyhedral oligomeric silsesquioxane (POSS) compound, trisilanolphenyl-POSS (TSP-POSS) was prepared via a modified two-step procedure with phenyltrichlorosilane as the starting material. The solubility of the TSP-POSS in polyimide (PI) solvents, including N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) was first evaluated. TSP-POSS could be dissolved in the test solvents with a solid concentration higher than 50 wt% and the obtained solution was stable both at room temperatures and in refrigerator at -18 °C for more than 1 month. TSP-POSS was then physically blended with a poly(amic acid) (PAA) obtained from 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) and para-phenylenediamine (PDA) with various adding proportions of 0, 5, 10, 15, 20, and 25 wt% (TSP-POSS in total solids). The obtained clear and homogeneous PAA/TSP-POSS solution was then thermally imidized at elevated temperatures to afford six PI/TSP-POSS composite films (PI-BP-0~PI-BP-25). For comparison, analogous composite films were prepared by blending TSP-POSS with another PI matrix, poly(pyromellitic anhydride-oxydianiline) (PIPMDA-ODA) at the same hybrid proportion (PI-0~PI-25). TSP-POSS exhibited quite different miscibility with these two PI matrixes. All of the composite films based on PIPMDA-ODA and TSP-POSS showed homogeneous nature and the films were optically transparent even at the high POSS loading of 25 wt%; however, the PIBPDA-PDA analogues showed poor compatibility with the POSS additive when the adding proportion was over 10 wt%. PI-BP-20 and PI-BP-25 films were thoroughly opaque with the haze values of 100%. In addition, the residual weight ratio of the composite films at 760 °C in nitrogen increased from 62.0 wt% (PI-BP-0) to 74.1 wt% (PI-BP-25).

Effect of isomerism on mechanical and tribological properties of thermoplastic polyimide films

Abstract A series of asymmetric polyimide (PI) films were prepared via polycondensation of 2,3,3′,4′-biphenyl-tetracarboxylic acid dianhydride (a-BPDA) with a pair of isomer 4,4′-oxydianiline (4,4′-ODA) and 3,4′-oxydianiline (3,4′-ODA). The effects of isomerism on the thermal stability, mechanical and tribological properties were systematically investigated. When molar fraction of 4,4′-ODA was increased in PI macromolecular chain, it had little significant effect on the nano-indentation hardness number and thermal stability. Furthermore, more of 4,4′-ODA monomer in PI increased the elongation at break but reduced the tensile strength, as well as it resulted in a lower coefficient of frictions(COFs). This evolution was related to macromolecular chain conformation caused by different monomer configurations. PI with a linear monomer (4,4′-ODA) resulted in a lower COFs and better wear-resistance.

The Preparations and Water Vapor Barrier Properties of Polyimide Films Containing Amide Moieties.

Flexible displays are a systematic revolution in the field of display, in which high-performance and high-barrier polymer substrates are considered to be one of the most important key materials. In this work, high water vapor barrier polyimides containing amide moieties were synthesized via the ternary polymerization of 4,4′-diaminobenzailide (DABA), 4,4′-diaminodipheny ether (ODA), and 3,3′,4,4′-biphenyl-tetracarboxylic acid dianhydride (BPDA) followed by thermal imidization. The relationship between the content of amide moieties and the water vapor barrier property of the prepared polyimides was studied by means of density test, water absorbing test, water contact angle test, water vapor permeation test, fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), thermogravimetry coupled with fourier transform infrared spectrometry (TG-FTIR), wide-angle X-ray diffraction analysis (WXRD), mechanical performance test, etc. The results show that the introduction of amide groups into polyimide (PI) main chains can improve the water vapor barrier properties of the polyimides effectively. The water vapor transmission rate (WVTR) of the polyimide films can be improved from 8.2365 g·(m2·24 h)−1 to 0.8670 g·(m2·24 h)−1 with the increasing content of amide moieties.

Polyimide Cellulose Nanocrystal Composite Aerogels

Cellulose nanocrystals derived from tunicates (t-CNC) were used as a reinforcing nanofiller for polyimide aerogels. Two sets of polyimide aerogels, containing either 2,2′-dimethylbenzidine (DMBZ) or 4,4′-oxydianiline (ODA) and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride (BPDA) cross-linked with 1,3,5-tris(4-aminophenoxy)benzene (TAB), were studied. Total solids composition of the aerogels were kept constant at 7.5 wt %, with 0–13.33 wt % of the total solids being the carboxylic acid-functionalized t-CNC (t-CNC–COOH) filler. The incorporation of the t-CNC–COOH, with carboxylic acid content of either 560 or 920 mmol/kg, in the polyimide aerogel networks improved both physical and mechanical properties of the final materials. Isothermal aging of t-CNC–COOH aerogel composites was also conducted at 150 and 200 °C for 24 h. Higher content t-CNC–COOH/polyimide aerogels showed less change in their density and reduced shrinkage during aging, which further emphasized the effect of the t-CNC–COOH reinforcemen...

Preparation and Properties of Copolyimides Containing Fluorine and Alicyclic Group

The copolyimides containing fluorine and alicyclic groups were synthesized from 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and two dianhydrides, 1,2,3,4-cyclobutanetrtracarboxylic dianhydride (CBDA) and 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA) in various mole ratios via thermal imidization. The introduction of fluorinated group and alicyclic structure into polyimide improved the transparency of copolyimides. The structure and properties of copolyimides were characterized by FT-IR, UV-vis and solubility testing, and the effect of monomers on the properties of polyimides was also investigated. These experimental results showed that the copolyimides containing a higher mole ratio of CBDA have higher optical transparency and better solubility in organic solvents.

Synthesis of 1,4-Bis(3-amino-5-trifluoromethylphenoxy)Benzene and Properties of the Polyimide Film Therefrom

Firstly, 1,4-bis(3-nitro-5-trifluoromethylphenoxy)benzene(I) was synthesized through the nucleophilic substitution reaction of 3,5-dinitrobenzotrifluoride and 1,4-dihydroxybenzene in the presence of potassium carbonate. Then, the diamine monomer 1,4-bis(3-amino-5-trifluoromethylphenoxy)benzene (II) was obtained through the catalytic reduction with hydrazine and Pd/C. These fluorinated polyimides (PI) were synthesized from the fluorinated diamine II with four kinds of dianhydrides, including pyromellitic dianhydride (PMDA), 3,3’,4,4’-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3’,4,4’-oxydiphthalic anhydride (ODPA) and 3,3’,4,4’-benzophenonetetracarboxylicdianhydride (BTDA) respectively, via thermal imidization of poly(amic acid) (PAA). The structure and properties of these obtained fluorinated PIs were characterized. These experimental results showed that these fluorinated PI films exhibited excellent optical transmittance in the visible region and thermal resistance. The PI derived from ODPA showed the best optical transparency with the transmittance higher than 85.38 % at 450 nm. These PIs also exhibited good thermal properties with 5 wt% thermal decomposition temperature above 533 °C.

Synthesis and Characterization of Chiral Poly(Amide-Imide) Containing L-Alanine

A novel chiral poly(amide imide) containing L-alanine was synthesized by direct polycondensation reaction of newly synthesized N,N’-(4,4’-diphthaloyl)-bis-L-alanine diacid with 4,4’-diaminodiphenyl ether in a medium consisting of N-methyl-2-pyrrolidone (NMP), triphenylphosphite (TPP), calcium chloride (CaCl2), and pyridine. The new chiral diimide-diacid monomer was synthesized by direct reaction of 3,3’-4,4’-Biphenyl tetracarboxylic acid dianhydride with L-alanine in acetic acid under refluxing conditions. The resulting compounds were obtained in quantitative yields and high purity. The synthetic diacid monomer was characterized by elemental analysis, 1H-NMR spectroscopy, FT-IR techniques and specific rotation, the obtained polymer was characterized by FTIR techniques, specific rotation and solubility testing.

Fluorinated phenylethynyl-terminated imide oligomers with reduced melt viscosity and enhanced melt stability

Two novel fluorinated phenyethynyl-contained endcapping agents, 4-(3-trifluoromethyl-1-phenylethynyl)phthalic anhydride (3F-PEPA) and 4-(3,5-bistrifluoromethyl-1-phenylethynyl)phthalic anhydride (6F-PEPA) were synthesized, which were employed to synthesize two fluorinated model compounds, N-phenyl-4(3-trifluoromethyl)-phenylethynylphthalimide (3F-M) and N-phenyl-4(3,5-bitrifluoromethyl)-phenylethynyl phthalimide (6F-M). The thermal cure kinetics of 3F-M and 6F-M were analyzed using DSC and compared to the unfluorinated derivative, N-phenyl-4-phenylethynylphthalimide (PEPA-M). The thermal cure temperatures of 3F-M and 6F-M were 399 and 412 °C, which were 22 and 35 °C higher than that of PEPA-M, respectively. The thermal cure kinetics of 3F-M and 6F-M best fit a first-order rate law, although 3F-M and 6F-M reacted slower than PEPA-M. However, the exothermic enthalpy of 3F-M and 6F-M were only half of PEPA-M. Based on the model compounds study, a series of fluorinated phenylethynyl-terminated imide oligomers (F-PETIs) with different calculated molecular weights (Calc'd Mn) were synthesized by thermal polycondensation of 2,3,3′,4′-biphenyltetracarboxylic acid dianhydride (a-BPDA) and 3,4′-oxydianiline (3,4′-ODA) using 3F-PEPA or 6F-PEPA as the endcapping agent. The substituent effects of the trifluoromethyl (−CF3) groups on the thermal cure behavior and melt processability of F-PETIs were systematically investigated. Experimental results reveal that the melt processability of F-PETI was apparently improved by the reduced resin melt viscosities and the enhanced melt stability due to the incorporation of the −CF3 groups in the imide backbone. All of those F-PETIs exhibit outstanding thermal and mechanical properties.

Sul-containing fluorinated polyimides for optical waveguide device

Novel sul-containing fluorinated polyimides have been synthesized by the reaction of 2,2′-bis-(trifluoromethyl)-4,4′-diaminodiphenyl sulfide (TFDAS) with 1,4-bis-(3,4-dicarboxyphenoxy)benzene dianhydride (HQDPA), 2,2′-bis-(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4,4′-oxydiphthalicanhydride (ODPA) or 3,4,3′,4′-biphenyl-tetracarboxylic acid dianhydride ( s-BPDA). The fluorinated polyimides, prepared by a one-step polycondensation procedure, have good solubility in many solvents, such as N-methyl-2-pyrrolidinone (NMP), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), cyclohexanone, tetrahydrofuran (THF) and m-cresol. The molecular weights ( M n's) and polydispersities ( M n/ M w's) of polyimides were in the range of 1.24 × 10 5 to 3.21 × 10 5 and 1.59–2.20, respectively. The polymers exhibit excellent thermal stabilities, with glass-transition temperatures ( T g) at 221–275 °C and the 5% weight-loss temperature are above 531 °C. After crosslinking, these polymers show higher thermal stability. The films of polymers have high optical transparency. The novel sul-containing fluorinated polyimides also have low absorption at both 1310 and 1550 nm wavelength windows. Rib-type optical waveguide device was fabricated using the fluorinated polyimides and the near-field mode pattern of the waveguide was demonstrated.

Formation of silver nanoclusters in transparent polyimides by Ag-K ion-exchange process

Silver nanoclusters embedded in two transparent fluorinated polyimides, 4,4'-hexafluoroisopropylidene diphthalic anhydride – 2,3,5,6-tetramethyl paraphenylene diamine (6FDA-DAD) and 3,3',4,4' – biphenyltetracarboxylic acid dianhydride – 1,1-bis(4-aminophenyl)-1-phenyl-2,2,2-trifluoroethane (BPDA-3F), have been produced by surface modification with KOH aqueous solution followed by K-assisted Ag doping and thermal reduction in hydrogen atmosphere. The reaction rate of the nucleophilic hydrolysis in KOH, studied by Fourier transform infrared spectroscopy (FT-IR) and Rutherford backscattering spectrometry (RBS), depends on the polyimide chemical structure. After ion-exchange in AgNO3 solution and subsequent annealing, the polyimide structure recovery was monitored by FT-IR whereas the characteristic surface plasmon absorption band of silver nanoparticles was evidenced by optical absorption measurements. The structure of silver nanoclusters as related to size and size distribution in the different polyimide matrices was thoroughly investigated by Transmission electron microscopy (TEM) and X-ray diffraction (XRD). The collected data evidenced a uniform distribution of Ag clusters of nanometric size after thermal treatment at 300 ○C in both polyimides. For the same ion-exchange treatment parameters and annealing temperature, XRD analyses evidenced the presence of crystallites with similar sizes.

Effects of Structural Isomerism and Precursor Structures on Thermo-optic Coefficients of BPDA/PDA Polyimide Films

The effects of the structural isomerism and the alkyl side-chain lengths in the precursors of BPDA/PDA polyimide (PI) on the temperature dependence of the refractive indices (i.e. thermo-optical coefficients) have been investigated. The PIs were formed on Si substrates by thermal curing of a) poly(amic acid)s (PAA) derived from three isomers (s-, a-, and i-) of biphenyltetracarboxylic acid dianhydride (BPDA) and p-diminobenzene (PDA) and b) poly(amide alkylester)s (PAEs) having methyl-, n-propyl-, n-pentyl-, and n-octyl side chains. The TO coefficients of PIs increase as the average refractive indices and thermal expansion coefficients increase, which can be well explained with the derivative form of the Lorentz-Lorenz formula. The absolute values of TO coefficients for s-BPDA/PDA are smaller than those expected from their refractive indices, which is due to the dense molecular packing and the small coefficient of thermal expansion. Significantly larger TO coefficients were observed for the PI films prepared from PAEs than that from PAA, indicating that the larger volatile components (alcohols) eliminated during thermal imidization cause loose molecular packing in the former PIs. The use of structural isomers and chemical modification of precursors are effective to control the TO coefficients and their anisotropies in BPDA/PDA films.

Improvement of bond strength of BPDA‐PDA‐type polyimide film by corona discharge treatment

AbstractAromatic polyimide film composed of biphenyl tetracarboxylic acid dianhydride (BPDA) and p‐phenylene diamine (PDA) is a very stable polymer at high temperatures and very useful for the electronics industry. Bonding properties were improved by corona discharge treatment of this film. The chemical modification method was applied for generated functional groups, that is, carboxylic, hydroxyl, and amino groups in the gas phase, and the quantity of these functional groups was determined by X‐ray photoelectron spectroscopy. The functional groups increased with corona energy, leveling off at a specific corona energy. The bond strength of the copper foil/adhesive/polyimide film was determined. The relationship between bond strength and functional group content was analyzed by multivariate analysis. Bond strength could be sufficiently correlated with functional group quantity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3403–3408, 2006