Preparation of soluble poly(amide imide) derivatives with metal salts and phosphorous compounds

Soluble poly(amide imide) derivatives were prepared through the direct polycondensation of 1,2,4‐benzenetricarboxylic acid and three diamines—bis[4‐(3‐aminophenoxy)phenyl]sulfone, bis(4‐aminophenyl)‐1,4‐diisopropylbenzene, and 4,4′‐oxydianilne—in the presence of metal salts and phosphorous compounds. Phosphonium salt, which was used as the initiating species and was prepared by the reaction of the metal salts and phosphorous compounds, reacted with 1,2,4‐benzenetricarboxylic acid to form acyloxy phosphonium salt, and then the salt was reacted with a diamine for the preparation of the prepolymers. The prepolymers were converted into the corresponding poly(amide imide)s in a homogeneous solution state at 180°C. The poly(amide imide)s showed good thermal and mechanical properties. Glass‐transition temperatures were observed from 240 to 270°C in differential scanning calorimetry traces. A melting endotherm was not observed for the polymers with differential scanning calorimetry. The initial decomposition occurred around 400°C according to thermogravimetric analysis, and major weight loss was observed from 610 to 680°C. The poly(amide imide)s had comparatively good solubility in aprotic polar solvents at concentrations high enough (～30%) for the fabrication of various forms. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1399–1407, 2002     

Synthesis and characterization of polyimides from divalent metal salts of p-aminobenzoic acid

Some 50 metal-containing polyimides with the metallic elements (Mg, Ca, Sr, Ba, Pb, Co, Ni) in the main chain were prepared first by reacting pyromellitic dianhydride (PMDA) with the mixture of divalent metal salts of p-aminobenzoic acid [ABA(M)] and 4, 4'-diaminodiphenylmethane (MDA) to form polyamic acid salts, and then the desired polyimides were obtained in high yield by separating the polyamic acid salts from the solvent and heating them under the imidization conditions. The structures of the samples were characterized by ¹H-NMR and IR, and the thermal properties of polyimides were measured by TG-DTA. It was found that the thermooxidative stability of polyimides decreased as a small amount of a metal element was introduced, and the stability of polymer varied slightly or tends to constancy as the metal content increased to a certain degree. In addition, the inherent viscosity of the polyamic acid salt solutions also decreased markedly with the increase of the metal content. © 1996 John Wiley & Sons, Inc.     

Positive photosensitive polyimides using polyamic acid esters with phenol moieties

Polyimide resists developable with basic aqueous solutions were realized by polyamic acid esters with phenol moieties (PPh's) and naphthoquinone diazides. The polyimide precursors (PPh's) were synthesized from diamines and dicarboxylic acids that have phenol moieties through ester linkage. A selective reaction of alcohol groups with acid dianhydride groups made the synthesis of the PPh's possible, even if the phenol groups were in the reaction mixtures. The PPh's were soluble in basic aqueous developer, but their dissolution rates were too low for use as resists. To increase the resist dissolution rate, polyamic acids were added to the PPh's. By adjusting the dissolution rates in basic aqueous developers, fine patterns could be realized. The polyimide resists had high thermal stability and reliable adhesive property to silicon substrate. © 1994 John Wiley & Sons, Inc.     

Surface-Enhanced Raman Scattering As an In-Situ Probe of Polyimide/Silver Interphases

The molecular structure of interphases formed by chemically curing the polyamic acid of pyromellitic dianhydride (PMDA) and oxydianiline (ODA) against meta-aminothiophenol (m-ATP)-primed silver substrates was determined using surface-enhanced Raman scattering (SERS) and reflection-absorption infrared spectroscopy (RAIR). It was found that m-ATP was adsorbed dissociatively onto silver substrates through the sulfur atoms. When polyamic acid was deposited onto silver substrates pretreated with m-ATP, acid groups of the polyamic acid combined with amino groups of m-ATP to form ammonium carboxylate salts near the interphase. SERS and RAIR results indicated that the structure of the interphase was significantly different from that of the bulk polymer. Chemical curing of the polyamic acids located in the interphase was suppressed because of the formation of ammonium carboxylate salts. However, the bulk of the polyamic acid films was highly cured to form polyimide. It was also found that more isoimide groups were formed when thin polyamic acid films were chemically cured in acetic anhydride/pyridine solutions than in acetic anhydride/triethylamine solutions.     

Adhesion and interface studies between copper and polyimide

The adhesion and interface structure between copper and polyimide have been studied. Polyimide films were prepared by spinning a polyamic acid solution (Du Pont PMDA-ODA) in an NMP solvent onto a Cu foil, followed by thermal curing up to 400°C. The adhesion strength was measured by a 90° peel test. The peel strength of 25 μm thick Cu foil to 25 μm thick polyimide substrate was about 73 g/mm with the peel strength decreasing with increasing polyimide thickness. Cross-sectional TEM observation revealed very fine Cu-rich particles distributed in the polyimide. Particles were not found closer than 80-200 nm from Cu boundary. These Cu-rich particles were formed as a result of reaction of polyamic acid with Cu during thermal curing. We attribute the high peel strength to interfacial chemical bonding between Cu and polyimide. This behavior is in contrast to vacuum-deposited Cu onto fully cured polyimide.     

Comparison of one-pot and two-step polymerization of polyimide from BPDA/ODA

The one-pot method polymerization of polyimide was carried out from 3,3′,4,4′-biphenyl tetracarboxylic dianhydride (BPDA) and 4,4′-oxydianiline (ODA) by the use of p-chloro-phenol as the solvent. The behavior of the polymerization was compared with that of the two-step method. The imidization reaction in the one-pot method proceeds completely in this system at even a low temperature such as 100°C. In the course of the film preparation from the solution, the embrittlement occurs when the film is prepared from polyamic acid solution, while it does not occur in the case of that from the solution of the one-pot method. A molecular weight of polyimide film is almost the same as that of precursor polyimide in the solution. In the same way, that of polyimide film is almost the same as that of precursor polyamic acid. The mechanical properties of the polyimide film prepared by the one-pot method are similar to those by the two-step method. © 1996 John Wiley & Sons, Inc.     

聚酰胺酸合成工艺与聚酰亚胺膜制备及表征

聚酰亚胺是一类新型高性能的聚合物材料,是由聚酰胺酸脱水环化而成,因此高分子量的聚酰胺酸是获得高性能PI的前提。探讨了聚酰胺酸合成过程中的影响因素,得出了合成高分子量的聚酰胺酸的最佳工艺条件为:均苯四羧酸二酐与4,4' 二氨基二苯醚摩尔比为1.015～1.020∶1,反应温度20℃,反应时间为3h,聚酰胺酸在N 甲基 2 吡咯烷酮中的特性粘度为0.62dL/g左右。采用热转化法将聚酰胺酸脱水环化制备成均苯型聚酰亚胺膜,通过差示扫描量热法、红外光谱等进行了表征,其玻璃化转变温度为365～385℃,拉伸强度达192.4MPa,表明得到的聚酰亚胺膜具有优良的机械性能。     

新型聚酰亚胺薄膜的制备及其性能研究

采用2,4,6-三甲基间苯二胺（TMmPDA）、4,4＇-二氨基二苯醚（DADPE）和3,3＇,4,4＇-四羧基联苯二酐（BP-DA）为主原料,摩尔比为1∶4∶5,合成得到了三甲基间苯二胺型聚酰胺酸（TMPAA）溶液,涂膜,热亚胺化,制得了三甲基间苯二胺型聚酰亚胺（TMPI）薄膜,并对其粘度、力学性能等进行了研究。     

Physicochemical characterization of alloy of polyimide with varying degree of crosslinking through diisocyanates

Polyimide alloys are prepared by blending the crosslinked and uncrosslinked polyamic acid components and followed by thermal imidization. The blend components can be synthesized by the reaction of polyamic acid with the varying concentration of crosslinker [here methylene bis (4-phenyl isocyanate or MDI)] from 1.54 × 10^?2 mol/L (i.e. hypothetically calculated critical crosslinker concentration or CCC) to 1.54 × 10^?6 mol/L. This communication discusses the synthesis and characterization of polyimide (PI) blends and alloys prepared by varying degrees of crosslinking introduced via isocyanate-amic acid reaction. The polyimides were prepared by thermally imidizing the polyamic acid blends at different curing temperatures from 50°C to 350°C. The degree of imidization and residual solvent content for blends having varying mole fractions of crosslinked (or branched) and uncrosslinked components and two extreme conditions and at specified temperature-time profiles have been studied. The resultant PI-MDI blends have exhibited synergism on mechanical properties. The improvement in mechanical properties, however, was significantly higher at the lower imidization temperature (i.e. 50°C to 150°C). The feasibility of preparing polyimide alloys with synergistic combinations of crosslinked and uncrosslinked polyimide components was inferred.     

Luminous polyimide bearing the coumarin 6 chromophore in the side group: Synthesis and fluorescence image patterning

Coumarin was reacted with polyamic acid to form a luminous polyimide that is highly soluble in organic solvents and displays good thermal stability. Luminous side-chain coumarin 6 polyimide was obtained from incorporation of sulfonated coumarin 6 into polyamic acid. This polymer appeared in reddish brown solids and unusually exhibited a fairly strong visible light-emission of a yellowish green color. Fluorescence image patterning of side-chain coumarin 6 polyimide was successfully conducted by microtransfer molding of the polyamic acid and the subsequent thermal treatment for imidization. The polyimides exhibit high fluorescence, opening the possibility of new applications for these polymers.     

Preparation and properties of soluble and colorless fluorine-containing photoreactive polyimide precursors

Photoreactive polyimide precursors, which are readily soluble in common organic solvents and optically transparent at light of 365 nm wavelength (i-line), similar to aliphatic polyimide precursors, were obtained by polycondensation of biphenyltetracarboxylic dianhydride (BPDA) and fluorine-containing diamine compounds. In particular, the polyimide precursor prepared from 2,2 bis(3-amino-4-methylphenyl) hexatluoropropane showed high solubility in common organic solvents and complete transparence at i-line wavelength. A 3 μm thick film of the polyimide precursor on a silicon wafer was exposed and developed, and offered high resolution (0.5μm line) patterns with an aspect ratio of 6.0. This polymide precursor swells very little in the developing solvent, resulting in the high resolution. Conversion of polyamic acid to polyimide at several curing temperatures was observed by infrared spectrophotometer and thermogravimetry.     

Synthesis of polyhydrazones by diazo coupling reaction of bisacetoacetamides with diazonium salts

Summary Hydrazone polymers were prepared by the diazo coupling reaction of bisacetoacetamides with diazonium salts under mild basic conditions. Bisacetoacetamides 1 and 2 having two 1,3-diketo groups were prepared by the reaction of aromatic diamines with diketene. Diazonium salts 3–5 were prepared by the reaction of aromatic diamines with nitrous acid in an aqueous HCl. A diazonium salt was isolated in a stable form after exchanging chloride with fluoroborate. The resulting polymer structure was determined by spectroscopic methods to be mainly polyhydrazone. The hydrazone unit was found stabilized by the intramolecular hydrogen bonding. The polymer obtained from 2 and 5 was soluble in organic solvents and showed the UV maximum peak at 376 nm in dimethyl sulfoxide. Received: 2 February 2001/Accepted: 13 March 2001     

Cresylic soluble polyimides

Polyimides are prepared by reaction of dianhydrides with aromatic diamines under dehydrating conditions to insure conversion of the polyamic acids to polyimides. Cresylic acid solubility is observed only for cyclopentane dianhydride and benzophenone dianhydride. Most of the batches are made from BPDA, since it is the preferred dianhydride for thermal stability. Of 19 aromatic diamines only 2,4- and 2,6-diaminotoluene, 2,4-diaminoanisole, 4,5-dimethyl-1,2-phenylene diamine and 1,5-diamino-4,8-dihydroxyanthraquinone contribute a great deal toward making soluble polyimides of BPDA. 2,4-Diamino-acetanilide when used as the only diamine also gives a soluble polyimide with BPDA. The solubility of polyimides can be correlated with their solubility parameters, their symmetry, and their tendency to hydrogen bond.     

Simulation of dry‐spinning process of polyimide fibers

As one type of high‐performance fibers, the polyimide fibers can be prepared from the precursor polyamic acid via dry‐spinning technology. Unlike the dry‐spinning process of cellulose acetate fiber or polyurethane fiber, thermal cyclization reaction of the precursor in spinline with high temperature results in the relative complex in the dry‐spinning process. However, the spinning process is considered as a steady state due to a slight degree of the imidization reaction from polyamic acid to polyimide, and therefore a one‐dimensional model based on White‐Metzer viscoelastic constitutive equation is adopted to simulate the formation of the fibers. The changes of solvent mass fraction, temperature, axial velocity, tensile stress, imidization degree, and glass transition temperature of the filament along the spinline were predicted. The effects of spinning parameters on glass transition temperature and imidization degree were thus discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Formation of graphite fiber–polyimide prepregs by electrodeposition

Nonaqueous electrodeposition of polyamic acid of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether was carried out from an emulsion containing a solvent, precipitant, emulsifier, and the polyamic acid. The amount of polyamic acid deposited onto the graphite fibers was dependent on electrodeposition parameters such as the applied current, the amount of polyamic acid (solid content), precipitant/solvent (P/S) ratio, and the acid/base (COOH/TEA) mole ratio. The weight gain of fibers increased with increased current density, P/S ratio, solid content, and deposition time. A maximum weight gain of fibers of about 95% was obtained from an emulsion composed of 3 wt % solid content, P/S ratio of 3 : 1, and TEA/COOH ratio of 1 : 1. The electrodeposition of polyamic acid onto graphite fibers proceeded in accordance with the Faraday's law of electrolysis and a Coulombic efficiency of about 62.2 mg/C was attained. Thermal analysis shows that the cured polyimide coatings were thermally stable up to 500°C. © 1996 John Wiley & Sons, Inc.     

Morphology and size control of inorganic particles in polyimide hybrids by using SiO2-TiO2 mixed oxide

Polyimide/inorganic hybrids were prepared by sol-gel reaction starting from tetraethoxysilane (TEOS), and tetrabutyl titanate (TBT) in the solution of polyamic acid in N,N-dimethylformamide. The hybrid films were obtained by the hydrolysis-polycondensation of TEOS and TBT in polyamic acid solution, followed by the elimination of solvents and imidization process. Binary polyimide/SiO₂ and polyimide/TiO₂ hybrids, as well as ternary polyimide/SiO₂-TiO₂ hybrids (with varied ratio of SiO₂ to TiO₂) were prepared to study the effects of the recipes and inorganic components on the morphologies of the polyimide hybrids. Transparent films with much higher inorganic content can be obtained in ternary polyimide hybrids, while lower inorganic content in binary hybrids. The results also indicate that the inorganic particles are much smaller in the ternary systems than in the binary systems, the shape of the inorganic particles and the compatibility for polyimide and inorganic moieties are varied with the ratio of the inorganic moieties in the hybrids. The completely imidization temperature of the polyamic acid was delayed, and furthermore, the thermal stability of polyimide was enhanced through the incorporation of the inorganic moieties in the hybrid materials.     

聚砜酰胺酸和聚砜酰亚胺的微波辐射合成

采用4，4'-二氨基二苯砜(DDS)与均苯四酸二酐(PMDA)为单体进行微波辐射溶液聚合反应，所得的聚酰胺酸进行固相微波辐射亚酰化。考察了微波辐射时间、反应温度、单体浓度、单体配比等因素对聚合物的特性粘数、转化率的影响，并与热聚合进行比较，用红外及核磁共振的测试方法对聚合物的结构进行了表征，通过红外光谱表征了聚酰亚胺的亚酰化度。实验结果表明：微波辐射不仅能缩短缩聚反应时间，还能提高缩聚物的特性粘数和转化率。固相微波辐射使聚酰胺酸的亚酰化时间缩短，亚酰化度增大。合成的聚酰胺酸和聚酰亚胺都具有一定的荧光性能，聚酰亚胺具有一定的磁性。     

Synthesis and characterization of self-metallizing gold-doped polyimide films

State-of-the-art methods for producing reflective polymer films for space applications involve multiple steps, and the integrity of the metal–polymer interface is less than optimal. A more efficient process was developed that consists of doping polyamic acid resins with gold additives and curing them to form self-metallizing polyimide films. Several moderately reflective, flexible metallic gold films were produced that have good thermal stability and mechanical properties, a strong metal–polymer interface, and in some cases, electrical conductivity. It was found that the polymer system, gold additive, gold concentration, and heat treatment all affect the reflectivity, flexibility, and conductivity of the resulting polyimide films by affecting the degree of metallization of the film surface. © 1995 John Wiley & Sons, Inc.     

聚酰胺酸纺丝溶液的流变性能研究

由均苯四酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)在N,N-二甲基乙酰胺(DMAc)中共聚合制得聚酰亚胺前驱体——聚酰胺酸的纺丝溶液,采用哈克流变仪研究了溶液的流变性能。结果表明:聚酰胺酸溶液属于切力变稀的非牛顿流体;溶液的表观黏度随溶液温度的升高而降低,随溶液浓度的升高或聚合物特性黏度的增大而增大。溶液温度的升高、浓度的降低或聚合物特性黏度的减小均使得聚酰胺酸溶液呈现切力变稀行为的临界剪切速率变大,使得溶液的非牛顿指数增大,同时使得溶液的结构黏度指数减小。溶液的黏流活化能随剪切速率的增加或随溶液浓度的增高而下降。     

聚酰胺酸的合成及其酰亚胺化研究

采用均苯四酸二酐(PMDA)和4,4'-二氨基二苯醚(ODA)为单体,N,N-二甲基乙酰胺(DMAc)为溶剂,合成聚酰亚胺的前驱体聚酰胺酸(PAA)。研究了溶剂体系、反应温度、时间、投料比和总固含量等因素对所得聚酰胺酸特性黏度的影响。试制了聚酰胺酸和聚酰亚胺(PI)薄膜,对其进行了红外光谱分析及力学性能测试。