Synthesis and Properties of Lyotropicpara-Linked Aromatic Poly(amic ethyl ester)s

Neuber, Christian; Giesa, Reiner; Schmidt, Hans‐Werner

doi:10.1002/1521-3935(20020201)203:3<598::aid-macp598>3.0.co;2-6

Cited by 10 publications

(14 citation statements)

References 15 publications

(25 reference statements)

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“…1a), as shown by temperature-dependent wide-angle X-ray scattering. [1] By raising the temperature to 100 C, these structures melt into a homogeneous lyotropic solution (Fig. 1b).…”

Section: Resultsmentioning

confidence: 99%

“…[1] These liquid-crystalline solutions now permit the preparation of highly oriented films from a nematic lyotropic state, which is the topic of this paper. Thus, the present contribution deals with the deposition and bulk orientation of precursor polymers and polyimide films obtained from lyotropic solutions.…”

Section: Introductionmentioning

confidence: 99%

“…The synthesis and characterization of liquid-crystalline precursor polymer solutions [1] for polyimides permit for the first time the preparation of bulk-and surface-oriented polyimide thin films from the nematic lyotropic state by shear. A special shearing technique was developed and optimized to orient viscous solutions into thin films with thicknesses below 100 nm.…”

Section: Introductionmentioning

confidence: 99%

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Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s

Neuber

Giesa

Schmidt³

2003

Adv Funct Materials

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The synthesis and characterization of liquid‐crystalline precursor polymer solutions[1] for polyimides permit for the first time the preparation of bulk‐ and surface‐oriented polyimide thin films from the nematic lyotropic state by shear. A special shearing technique was developed and optimized to orient viscous solutions into thin films with thicknesses below 100 nm. The films produced were thermally imidized and characterized by polarized light microscopy, as well as polarized FTIR and UV‐vis spectroscopy before and after imidization. The dichroic ratios (DRs) before imidization were determined as 5 by FTIR, and 4.5 by UV‐vis spectroscopies. After imidization the DRs increased to 14 and 7, respectively. The shear‐oriented layers possess a surface profile in the form of striations, which was characterized by mechanical surface scanning and atomic force microscopy (AFM). The profile height was determined in the nanometer range in contrast to the profile distance in the micrometer range, thus the latter is a magnitude larger than the film thickness. To quantify and compare the orientation potential of the obtained orientation layers, cells with a liquid‐crystalline host and a dichroic azo dye as guest were prepared. Interesting for this class of rod‐like polyimides is that layers, which were cast from low concentration isotropic solutions and rubbed, exhibited an almost doubled DR of 15 compared to analogously prepared alignment layers based on commercial flexible polyimide systems (DR = 8).

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“…1a), as shown by temperature-dependent wide-angle X-ray scattering. [1] By raising the temperature to 100 C, these structures melt into a homogeneous lyotropic solution (Fig. 1b).…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s

Neuber

Giesa

Schmidt³

2003

Adv Funct Materials

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“…[13] Anhydrous NMP was purchased from Aldrich. All of the other solvents and chemicals were used as received.…”

Section: Methodsmentioning

confidence: 99%

“…In the course of our studies of order in lyotropic PAEs, [11][12][13] where the orientation in a two-dimensional thin film was investigated, we now want to examine the development of orientation in an elongated, fibrillar geometry. This was realized by dry-jet, wet-fiber-spinning of lyotropic solutions at a high solid content of 40 wt.-% in N-methylpyrrolidone (NMP) without the addition of any salts.…”

Section: Introductionmentioning

confidence: 99%

Polyimide Fibers Obtained by Spinning Lyotropic Solutions of Rigid‐Rod Aromatic Poly(amic ethyl ester)s

Neuber

Schmidt

Giesa

2006

Macro Materials & Eng

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Summary: Fibers were spun from a lyotropic solution of a high‐molecular‐weight (η = 5.89 g · dL−1), rigid‐rod, fully aromatic polyimide precursor polymer in a dry‐jet, wet‐spinning process in NMP. Acetone was identified as the coagulant of choice since fibers could be drawn extensively in this solvent, resulting in improved mechanical properties (tensile modulus: E = 17 GPa, strength at break: σbreak = 400 MPa, elongation at break: εbreak = 5.3%) and orientation, which was shown by WAXS patterns. SEM images showed a layered, skin‐core morphology without any visible fibrillation. Additional processing of these fibers by step‐wise hot‐drawing up to 400 °C under tension rendered oriented polyimide fibers with excellent mechanical properties. (E = 68 GPa, σbreak = 700 MPa, εbreak = 1%). An analysis of the WAXS diffraction patterns showed an improved orientation of the fibers in the axial and lateral directions; however, probably due to the CF3 side groups, the lateral distance was still too large for crystallization. SEM images of these imidized fibers showed, for the first time, a fibrillar morphology in addition to the typical, skin‐core, sheet‐like morphology.SEM image of the hot‐drawn fiber PI 4 (12). The image shows a skin‐core morphology which was delaminating into ribbons during preparation.magnified imageSEM image of the hot‐drawn fiber PI 4 (12). The image shows a skin‐core morphology which was delaminating into ribbons during preparation.

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Lyotropic Liquid Crystalline Polyamides Containing Aromatic, Heterocyclic Structures: Preparation and Properties

Liu

Wang

Liu

et al. 2006

Macro Chemistry & Physics

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Summary: A series of novel lyotropic liquid crystalline polyamides derived from 1,2‐dihydro‐2‐(4‐aminophenyl)‐4‐[4‐(4‐(aminophenoxyl)phenyl)]‐phthalazinone (DHPZ‐DA), p‐phenylene diamine (PPD) and terephthaloyl dichloride (TPC) have been successfully synthesized by the low temperature solution polycondensation method. The copolymers obtained with inherent viscosity of ≈1.21 to 3.29 dl · g−1, determined in NMP (1 wt.‐% LiCl) or concentrated H2SO4 at 25 °C, were confirmed to be amorphous by WAXD and differential scanning calorimetry (DSC). Their solubility was improved by the introduction of non‐coplanar, twisted phthalazinone moieties and ether linkages into the main chain with the result that they can be soluble in some polar solvents containing a small amount of LiCl. Their Tgs were all above 310 °C and 10% weight loss temperatures in nitrogen above 500 °C. Most of these polyamides can form an anisotropic phase in concentrated H2SO4, NMP (1 wt.‐% LiCl) and DMAc (1 wt.‐% LiCl) solutions, observed on a polarizing light microscope.Optical micrograph (×40) of polyamide P‐4060 at 10 wt.‐% in NMP/LiCl (1% w/v) solution at room temperature.imageOptical micrograph (×40) of polyamide P‐4060 at 10 wt.‐% in NMP/LiCl (1% w/v) solution at room temperature.

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Synthesis and Properties of Lyotropicpara-Linked Aromatic Poly(amic ethyl ester)s

Cited by 10 publications

References 15 publications

Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s

Polyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s

Polyimide Fibers Obtained by Spinning Lyotropic Solutions of Rigid‐Rod Aromatic Poly(amic ethyl ester)s

Lyotropic Liquid Crystalline Polyamides Containing Aromatic, Heterocyclic Structures: Preparation and Properties

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