Synthesis of novel polypyromellitimides with <i>n</i>‐alkyloxy side chains and their liquid‐crystal aligning property

Lee, Seong Jun; Jung, Jin Chul; Lee, Seung Woo; Ree, Moonhor

doi:10.1002/pola.20165

Cited by 41 publications

(40 citation statements)

References 27 publications

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“…[3][4][5][6][7][8][61][62][63][64][65][66][67][68][69][70][71] A few soluble aliphatic and aromatic PIs have been reported so far. 63,74 Most aromatic polyimides cannot be processed because they are insoluble and have a high glass transition temperature.…”

Section: Processabilitymentioning

confidence: 99%

“…63,74 Most aromatic polyimides cannot be processed because they are insoluble and have a high glass transition temperature. [3][4][5][6][7][8][61][62][63][64][65][66][67][68][69][70][71] Thus, they are first synthesized in a soluble precursor form and then processed in various ways, before finally being converted to PIs. [3][4][5][6][7][8][61][62][63][64][65][66][67][68][69][70][71] Poly(amic acid) (PAA) and poly(amic dialkyl ester) (PAE) are representative soluble precursors, which are soluble in N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide, and N,N-dimethylacetamine.…”

Section: Processabilitymentioning

confidence: 99%

“…[155][156][157][158][159] PIs are widely used as LC alignment layers because of their advantageous properties, such as excellent optical transparency, adhesion, heat resistance, dimensional stability and insulation. [65][66][67][68][69][70][71][72][73]95,124,125,155,156,[160][161][162][163][164][165][166][167] Such PI film surfaces need to be treated if they are to produce a uniform alignment of LC molecules with a defined range of pretilt angle values. [37][38][39][40][41][42]55,83,84,[108][109][110][111][112][113][114][115][116][117][118][119]…”

Section: Pis For Liquid Crystal Alignmentmentioning

confidence: 99%

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High performance polyimides for applications in microelectronics and flat panel displays

2006

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Polyimides (PIs) exhibit excellent thermal stability, mechanical, dielectric, and chemical resistance properties due to their heterocyclic imide rings and aromatic rings on the backbone. Due to these advantageous properties, PIs have found diverse applications in industry. Most PIs are insoluble because of the nature of the high chemical resistance. Thus, they are generally used as a soluble precursor polymer, which forms complexes with solvent molecules, and then finally converts to the corresponding polyimides via imidization reaction. This complexation with solvent has caused severe difficulty in the characterization of the precursor polymers. However, significant progress has recently been made on the detailed characterization of PI precursors and their imidization reaction. On the other hand, much research effort has been exerted to reduce the dielectric constant of PIs, as demanded in the microelectronics industry, through chemical modifications, as well as to develop high performance, light-emitting PIs and liquid crystal (LC) alignment layer PIs with both rubbing and rubbing-free processibility, which are desired in the flat-panel display industry. This article reviews this recent research progresses in characterizing PIs and their precursors and in developing low dielectric constant, light-emitting, and LC alignment layer PIs.

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Section: Processabilitymentioning

confidence: 99%

Section: Processabilitymentioning

confidence: 99%

Section: Pis For Liquid Crystal Alignmentmentioning

confidence: 99%

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High performance polyimides for applications in microelectronics and flat panel displays

2006

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“…The attaching of alkyl side chains to polyimides has recently been used to increase pretilt angles generated by the polyimides in alignment layer applications of liquid crystal displays (LCDs) and, thus, these studies are of great practical importance. [33][34][35][36][37][38][39] …”

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confidence: 99%

Soluble Polyimides Based on Diaminobenzoic Acid Alkylester

Tsuda

Kojima

2006

Polym J

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ABSTRACT:The synthesis and characterization of a novel series of soluble polyimides, that are based on diaminobenzoic acid alkylester (DBAE) having long-chain alkyl groups with 8-14 carbon atoms, are described. Polyimides obtained from 3,3 0 ,4,4 0 -benzophenonetetracarboxylic dianhydride (BTDA) and DBAE-8-14, and copolyimides based on BTDA, DBAE-8-14, and 4,4 0 -diaminodiphenylether (DDE) were insoluble in polar solvents such as N-methyl-2-pyrrolidone (NMP) and the effect of long-chain linear alkyl groups for the enhancement of solubility was not recognized. However, it was found that two methods improve the solubility. One is the use of branched alkyl groups such as nonan-5-yl and 2,6-dimethylheptane-4-yl, and the other is the use of relatively flexible diamine co-monomer, 4,4 0 -diaminodiphenylmethane (DDM). These polyimides and copolyimides based on DBAE were soluble in various polar solvents and exhibited good thermal stability in air and under nitrogen. The effect of DBAE for the enhancement of solubility was lower than the effects of alkyloxydiaminobenzene (AODB) and alkyldiaminobenzophenone (ADBP), probably due to the rigid ester linkage group in DBAE. [doi:10.1295/polymj.PJ2005257] KEY WORDS Polyimide / Soluble Polyimide / Diaminobenzamide Alkylester / Branched Alkyl Group / Copolymerization / Thermal Stability / Solubility / Polyimides exhibit excellent thermal and mechanical properties, and have extensive engineering and microelectronics applications.1 Aromatic polyimides such as pyromellitic polyimides are prepared from aromatic diamines and aromatic tetracarboxylic dianhydrides via poly(amic acids). Since conventional aromatic polyimides are insoluble, these polymers are usually processed as the corresponding soluble poly-(amic acid) precursors, and then either thermally or chemically imidized. However, owing to the instability of poly(amic acids) and the liberation of water in the imidization process, problems can arise. Extensive research has been recently carried out to improve the solubility of polyimides. We have reported the synthesis and characterization of soluble polyimides and copolyimides based on alicyclic dianhydride such as 2,3,5-tricarboxycyclopentyl acetic dianhydride (TCA-AH), 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (cyclohexene-DA), and 4-(2,5-dioxotetrahydrofuran-3-yl)-tetralin-1,2-dicarboxylic anhydride (tetralin-DA). [25][26][27] Conventional tetracarboxylic dianhydrides such as 3,3 0 ,4,4 0 -benzophenone tetracarboxylic dianhydride (BTDA) and alkyldiaminobenzophenone (ADBP) having long-chain linear alkyl groups with 9-14 carbon atoms (ADBP-9-14), 28 and BTDA and alkyloxydiaminobenzene (AODB) having long-chain linear alkyl groups with 10-14 carbon atoms (AODB-10-14) have also been used (Scheme 1). 29 It was concluded that ADBP with an even number of carbon atoms was effective in enhancing the solubility, while polymers based on ADBP with an odd number of carbon atoms remained insoluble. AODB bearing alkyl groups via an ether linkage are mo...

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“…[1][2][3][4][5][6] The mechanical rubbing of polyimide (PI) surfaces is the most commonly used technique for producing LC alignment layers, 7-21 which can induce stable homogeneous planar LC alignment 19,20 or homeotropic LC alignment. 14,18 The LC alignment properties such as the pretilt angle and electro-optical (E-O) performance on polyimide surfaces are known to be affected by the molecular structure of the polyimide such as the flexibility of the polymer backbone, isomeric structure of the mesogen end groups, spacer length, and spacer conformation in the side chains.…”

Section: Introductionmentioning

confidence: 99%

The effect of phenoxymethyl side groups on the liquid crystal alignment behavior of polystyrene derivatives

2009

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Abstract:We synthesized a series of polystyrene derivatives containing various side chain terminal moieties, such as phenoxymethyl, 4-methoxyphenoxymethyl, 4-fluorophenoxymethyl, 4-methylphenoxymethyl, and 4-trifluoromethoxyphenoxymethyl groups, using polymer analogous reactions, in order to investigate the effect of the side group on their liquid crystal (LC) alignment behaviors. The polymers containing 4-fluorophenoxymethyl, 4-methylphenoxymethyl, or 4-trifluoromethoxyphenoxymethyl side groups had lower surface energy values and the LC cells fabricated using the unrubbed films of these polymers showed homeotropic LC alignment behavior. The LC cells fabricated using the rubbed films of the polymers containing phenoxymethyl or 4-fluorophenoxymethyl groups showed homogeneous planar LC alignment behavior in which the LCs were aligned perpendicular to the rubbing direction. This homogeneous planar and perpendicular alignment behavior was ascribed to the favorable anisotropic interactions between the LC molecules and the side groups preferentially oriented perpendicular to the rubbing direction.

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Synthesis of novel polypyromellitimides with n‐alkyloxy side chains and their liquid‐crystal aligning property

Cited by 41 publications

References 27 publications

High performance polyimides for applications in microelectronics and flat panel displays

High performance polyimides for applications in microelectronics and flat panel displays

Soluble Polyimides Based on Diaminobenzoic Acid Alkylester

The effect of phenoxymethyl side groups on the liquid crystal alignment behavior of polystyrene derivatives

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