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Title: Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide)

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Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
National Institutes of Health (NIH)
OSTI Identifier:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Macromolecules; Journal Volume: 50; Journal Issue: 6
Country of Publication:
United States

Citation Formats

Bedoui, F., Murthy, N. S., and Kohn, J. Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide). United States: N. p., 2017. Web. doi:10.1021/acs.macromol.6b02473.
Bedoui, F., Murthy, N. S., & Kohn, J. Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide). United States. doi:10.1021/acs.macromol.6b02473.
Bedoui, F., Murthy, N. S., and Kohn, J. Mon . "Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide)". United States. doi:10.1021/acs.macromol.6b02473.
title = {Structure and Thermal Transitions in a Biomedically Relevant Liquid Crystalline Poly(ester amide)},
author = {Bedoui, F. and Murthy, N. S. and Kohn, J.},
abstractNote = {},
doi = {10.1021/acs.macromol.6b02473},
journal = {Macromolecules},
number = 6,
volume = 50,
place = {United States},
year = {Mon Feb 20 00:00:00 EST 2017},
month = {Mon Feb 20 00:00:00 EST 2017}
  • A series of poly(ester imide)s (PEIMs) has been synthesized from N-[4-(chloroformyl) phenyl]-4-(chloroformyl)phthalimide and different diols with methylene units of 4 to 12 (n). PEIMs with both even and odd methylene units exhibit a monotropic mesophase behavior during cooling due to the supercooling necessary for crystallization. Identification of this mesophase as a monotropic liquid crystal with smectic A order has been carried out via differential scanning calorimetry, wide angle X-ray diffraction (WAXD), small angle X-ray scattering, polarized light microscopy, and transmission electron microscopy. It is found that the methylene units in these chain molecules are also largely responsible for the formationmore » of this liquid crystal phase. After investigating different types of main chain mesogen-nonmesogen liquid crystal polymers, a general concept considering the contributions to enthalpy and entropy changes during the liquid crystal transitions may be associated with the relative rigidity, linearity, and regularity of the mesogenic groups compared to the methylene units. Detailed WAXDR study of fiber and powder patterns indicates that the degree of orientation and the order correlation lengths along and perpendicular to the direction of chain molecules (chain lateral packing and layer structure) not only increase with the number of methylene units but also show an even-odd alternation. A possible chain packing model is suggested. The morphology and defects of this smectic A liquid crystal phase are also discussed.« less
  • Highlights: Black-Right-Pointing-Pointer A novel biodegradable and nanostructured PAEI based on two amino acids, was synthesized. Black-Right-Pointing-Pointer ZnO nanoparticles were modified via two different silane coupling agents. Black-Right-Pointing-Pointer PAEI/modified ZnO BNCs were synthesized through ultrasound irradiation. Black-Right-Pointing-Pointer ZnO particles were dispersed homogeneously in PAEI matrix on nanoscale. Black-Right-Pointing-Pointer The effect of ZnO nanoparticles on the properties of synthesized polymer was examined. -- Abstract: A novel biodegradable and nanostructured poly(amide-ester-imide) (PAEI) based on two different amino acids, was synthesized via direct polycondensation of biodegradable N,N Prime -bis[2-(methyl-3-(4-hydroxyphenyl)propanoate)]isophthaldiamide and N,N Prime -(pyromellitoyl)-bis-L-phenylalanine diacid. The resulting polymer was characterized by FT-IR, {sup 1}H NMR,more » specific rotation, elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) analysis. The synthesized polymer showed good thermal stability with nano and sphere structure. Then PAEI/ZnO bionanocomposites (BNCs) were fabricated via interaction of pure PAEI and ZnO nanoparticles. The surface of ZnO was modified with two different silane coupling agents. PAEI/ZnO BNCs were studied and characterized by FT-IR, XRD, UV/vis, FE-SEM and TEM. The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAEI matrix on nanoscale. Furthermore the effect of ZnO nanoparticle on the thermal stability of the polymer was investigated with TGA and DSC technique.« less
  • Poly(p-phenylene terephthalamide) (PPTA or Kevlar[sup TM]) adopts an extended-chain crystal habit in the solid state which derives from the chain parallelism in its liquid crystalline (LC) phase. The objective of this dissertation is to investigate how the deviation from core linearity which is achieved by replacing terephthalic acid, a linear monomer, with 2,5-thiophenedicarboxylic acid, a monomer with a [approximately]148[degrees] bend, affects liquid crystalline properties of aromatic polyamides. The mesogenic properties of the 2,5-thiophene are initially verified for newly synthesized low molar mass diamide model compounds where the characteristic texture of the smectic A phase is observed by polarized optical microscopy.more » Differential scanning calorimetry (DSC) studies shows that the observed mesophase for the thiophene-based diamide is much narrower and exists at lower temperatures than that observed for the corresponding p-phenylene diamide. Extensions to macromolecules show that if each terephthalamide unit in PPTA is replaced with a 2,5-thiophenylamide unit, high molecular weight polymer can be synthesized and, moreover, such 2,5-thiophene-based aromatic polyamide (PPThA) is stable and exhibits liquid crystalline phases in concentrated sulfuric acid solutions. Preliminary mechanical properties of coarse fibers spun from the liquid crystalline solutions and isotropic solutions in sulfuric acid are compared. PPThA lyotropic solutions are studied using deuterium NMR spectroscopy. LC solutions may be aligned in a magnetic field to yield a [open quotes]single liquid crystal[close quotes]-a macroscopically oriented phase. In such uniaxial solutions, the transition to isotropic state at elevated temperatures may be indirectly monitored by deuterium NMR; quadrupolar interactions of the probe molecule (deuterated sulfuric acid) reflects changes in the macromolecular ordering. Direct monitoring of polymer order is accomplished using deuterium labeled PPThA.« less
  • Graphical abstract: - Highlights: • Chiral polymer with different functional groups was prepared in green route. • The surface of Al{sub 2}O{sub 3}-NPs was treated by KH550 as a silane coupling agent. • NCs of poly(amide-imide) and Al{sub 2}O{sub 3} were synthesized by ultrasonic irradiation. • TEM results show good dispersion of Al{sub 2}O{sub 3}-NPs in the poly(amide-imide) matrix. • The thermal and mechanical properties of the hybrid materials were improved. - Abstract: Novel chiral poly(amide-imide) (PAI)/Al{sub 2}O{sub 3} nanocomposites were prepared via incorporating surface modified Al{sub 2}O{sub 3} nanoparticles into polymer matrices for the first time. In the processmore » of preparing the nanocomposites, severe aggregation of Al{sub 2}O{sub 3} nanoparticles could be reduced by surface modification and γ-aminopropyltriethoxysilane. The optically active PAI chains were formed from the polycondensation reaction of N,N′-(pyromellitoyl)-bis-phenylalanine diacid with 2-(3,5-diaminophenyl)-benzimidazole in green condition. The obtained polymer and inorganic metal oxide nanoparticles were used to prepare chiral PAI/Al{sub 2}O{sub 3} nanocomposites through ultrasonic irradiation. The resulting nanoparticle filled composites were also characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy and thermogravimetric analysis (TGA) techniques. TGA thermographs confirmed that the heat stability of the prepared nanoparticle-reinforced composites was improved. Mechanical properties showed that the film containing 10 wt% of modified Al{sub 2}O{sub 3} had a tensile strength of the order of 83.6 MPa, relative to the 64.3 MPa of the pure PAI.« less
  • The lamellar gel/liquid-crystalline and the lamellar liquid-crystalline/reversed hexagonal phase transitions of aqueous dispersions of a number of synthetic phosphatidylethanolamines containing linear saturated, branched chain, and alicyclic fatty acyl chains of varying length were studied by differential scanning calorimetry, {sup 31}P nuclear magnetic resonance spectroscopy, and X-ray diffraction. For any given homologous series of phosphatidylethanolamines containing a single chemical class of fatty acids, the lamellar gel/liquid-crystalline phase transition temperature increases and the lamellar liquid-crystalline/reversed hexagonal phase transition temperature decreases with increases in hydrocarbon chain length. For a series of phosphatidylethanolamines of the same hydrocarbon chain length but with different chemical structures,more » both the lamellar gel/liquid-crystalline and the lamellar liquid-crystalline/reversed hexagonal phase transition temperatures vary markedly and in the same direction. These results suggest that for any given hydrocarbon chain length, there may be a critical thickness at which the liquid-crystalline phosphatidylethanolamine bilayer becomes unstable with respect to inverted nonbilayer phases such as the H{sub II} phase and that the temperature at which this critical thickness is reached is dependent upon that bilayers proximity to the hydrocarbon chain-melting phase transition temperature.« less