Solubility, polyimide films

Compared to Kapton, more sensitive soluble polyimide films were investigated [235-236]. A photosensitivity of up to 30 m2 J 1 was achieved in electrophotographic regimes. The photogeneration of the charge carriers occured via exiplex formation and the holes are the predominant carriers. The spectral... 

W.-C. Lee, C.-S. Hsu, and S.-T. Wu, Liquid crystal alignment with a photo-crosslinkable and solvent soluble polyimide film. Japanese Journal of Applied Physics... 

K. Murakami, K. Yamada, K. Deguchi, T. Shimizu and S. Ando, Preparation of soluble polyimide/MgO nanohybrid films by in situ hybridization method and evaluation of their thermal conductivity. J. Photopolym. Sci. Technol, 2010, 23,501-506. 

Starting materials and solvents were purchased from Aldrich Chemical Co. acetonitrile (ACN), N,N-dimethylformamide (DMF), and N-methyl-2-pyrrolidone (NMP) were obtained anhydrous in Sure/Seal bottles and used as received. The polyamic acid of PMDA-ODA (2545 Pyralin) was supplied by DuPont. The soluble polyimide XU-218, derived from 3,3, 4,4 -benzophenone tetracarboxylic dianhydride (BTDA) and diamino-1,1,3-trimethyl-3-phenylindan isomers (DAPI) was purchased from Ciba-Geigy Corp. The acetylene terminated imide oligomer powder (Thermid MC-600) derived from BTDA, aminophenylacetylene, and 1,3-bis (2-aminophenoxy) benzene (APB) was obtained from National Starch and Chemical Company. Kapton Type II (PMDA-ODA) films were obtained from DuPont Co., Apical polyimide films were obtained from Allied Corp., and Upilex Type-S and Type-R polyimide films derived from 3,3, 4,4 -biphenyl tetracarboxylic dianhydride (BPDA) plus p-phenylenediamine (PDA) and ODA, respectively were obtained from ICI Americas Inc. 

Polyimides for microelectronics use are of two basic types. The most commonly used commercial materials (for example, from Dupont and Hitachi) are condensation polyimides, formed from imidization of a spin-cast film of soluble polyamic acid precursor to create an intractable solid film. Fully imidized thermoplastic polyimides are also available for use as adhesives (for example, the LARC-TPI material), and when thermally or photo-crosslink able, also as passivants and interlevel insulators, and as matrix resins for fiber-reinforced-composites, such as in circuit boards. Flexible circuits are made from Kapton polyimide film laminated with copper. The diversity of materials is very large readers seeking additional information are referred to the cited review articles [1-3,6] and to the proceedings of the two International Conferences on Polyimides [4,5]. 

Table II. Solubilities of Polyimide Films Prepared with 6F...

Another method for solubilizing polyimide film by curing the polyamic acid for longer times at lower temperatures was attempted. The 6F + 4,4 -ODA film cured 1 hour at 300°C was found to be insoluble in DMAc at ambient temperature. Hie same material cured for 5 hours at 200 C was totally soluble in DMAc upon stirring for several hours. Hie enhanced solubility of this polymer could be due to a possible lowering in molecular weight or incomplete imidization of the polyamic acid. Hiis method for obtaining solubility is not a preferred method but is mentioned... 

The high refractive indices of polyimides, compared to many other polymers, combined with excellent optical clarity, have been exploited in the development of coatings in optoelectronic applications117. Soluble thin-film polyetherimides (OptiNDEX ), such as 188, with controlled refractive indices for use as optical coatings, have been prepared (Scheme 35). The refractive index is controlled through variation in the dianhydride and diamine composition. The polyimides exhibit good thermal stability at 400 °C, and Tg... 

The solubility of the polyimide films was qualitatively studied and the results are listed in Table 3. All the polyimide films were insoluble in common organic solvents except sulfuric acid. The BBH-based polyimides swelled in some solvents. BBH is bulky and consists of four isomers, and it would make the polymer chains somewhat loosely packed. 

We have investigated many macroscopic properties of the organo-soluble aromatic polyimide films and all of them exhibit anisotropic behaviors which are closely associated with the anisotropic structure in the films. One question still remains is whether we can find a common physics background to describe these properties. If we consider the fi-ee energy (or internal energy or energy) term, the first derivative of... 

In summary, we have briefly reviewed our understanding in the development of organo-soluble aromatic polyimides via molecular design and architecture control and the establishment of relationships between the anisotropic structure and properties in the films. These anisotropic structures and properties are also found to be film thickness and molecular weight dependent. In particular, the LOA behavior has led to a invention where these aromatic polyimide films can be used as UNB retardation compensators in LCDs to increase viewing angles. This technology initiated from our researches has been commercialized to produce compensators for wide applications in LCDs,... 

The organic solvent solubility of the starting polyimide can be modified by sulfonation to give water-soluble polyimide possessing film-forming properties. 

Aqueous amylose solution (1%) was prepared by dissolving amylose powder in hot water (80°C). A 1% salt free aqueous water-soluble chitosan (WSC) was obtained by the dialysis of a WSC solution that included NaCl produced by the neutralization of a dilute hydrochloric acid solution of WSC with NaOH. Each film having a thickness of 40-50 om was prepared by casting the amylose, WSC, or their mixed solutions at 60°C. A film of fully deacetylated chitosan was obtained by casting a 0.1 M aqueous AcOH solution of fully deacetylated chitosan (1%) on a Kapton (polyimide) film. The resulting acidic chitosan film was neutralized with 1M aqueous NaOH followed by washing with water and then dried. 

Jang et al. [85] prepared a highly kinked diamine (3-31 in Table 3.3), a fluorinated diamine (3-32 in Table 3.3), and a biphenyl based-fluorinated diamine (3-33 in Table 3.3) and studied the color intensity and optical properties of the synthesized polyimides. Introduction of kink structures disrupted effective CTC formation, leading to colorless polyimide films with high transmittance. Wang et al. [86] developed meta-diamine, namely 4,4 -/ /s (3-amino-5-trifluoro-methylphenoxy) biphenyl (3-34 in Table 3.3), with the aim of improving the melt processability and solubility of the polyimides. Shao et al. [87] designed a -CF3-substituted unsymmetrical diamine (3-35... 

A fluorinated aromatic dianhydride, 4,4 -(2,2,2-tri-fluoro-l-[3,5-ditrifluoromethylphenyl]ethylidene) diphthalic anhydride (9FDA) (3-55 in Scheme 3.8) was synthesized by Li et al. [107] and the solubility, thermal, and mechanical properties as well as electrical and optical properties were systematically investigated. Transmittance of the polyimide films at450nm... 

Solvent-Soluble Polyimides. Materials in this class are also termed preimidized polyimides because the film-forming polymer is a polyimide rather than a polyimide precursor such as a polyamic acid. Thus, the curing process for these materials involves only removal of solvent. In some instances, a high... 

Thus, the results of the research indicate that it is possible to use oligoamic acid based on 4,4 -diaminodipheniloxide and dianhydiide 4,4 -diphenyl-l,5-diazobicyclo/3,3,0/ octane-2,3,6,7-tetracarboxilic acid which have a volumetric three-dimensional stmc-mre and block the implementation of interactions between aromatic PAA macromolecules as copolymer. We can get polyimide film-forming materials with high dielectric properties, which are soluble in aprotic amide solvents by chemical imidization. 

Chemical imidization is less attractive for commercial and experimental polyimides that are tested and used in the form of films, but chemical imidation has been the preferred method concerning experimental polyimides that are soluble in organic solvents in the state of full imidation. At this respect it is worthy to remark that 100% conversion in the ring closure step is virtually impossible to achieve, particularly for thermal imidation at high temperature (about 300 °C) in the solid state, due to the complexity of the process and to the inherent molecular regidity of insoluble polyimides. However, for soluble polyimides, solution imidization is possible at mild reaction temperatures, for instance 150-200 °C, with 100% conversion, and avoiding undesirable side reactions which lead to insolubility and infusibility [61]. 

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