Liquid Crystalline Ionomers Research Articles

A novel PEO-based blends solid polymer electrolytes doping liquid crystalline ionomers

A novel PEO-based blends solid polymer electrolytes doping liquid crystalline ionomers (LCI), PEO/PMMA/LiClO4/LCI, and PEO/LiClO4/LCI were prepared by solution casting technology. Scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS) analysis proved that LCI uniformly dispersed into the solid electrolytes and restrained phase separation of PEO and PMMA. Differential scanning calorimetry (DSC) results showed that LCI decreases the crystallinity of blends solid polymer electrolytes. Thermogravimetric analysis (TGA) proved LCI not only improved thermal stability of PEO/PMMA/LiClO4 blends but also prevent PEO/PMMA from phase separation. Infrared spectra results illustrated that there exists interaction among Li+ and O, and LCI that promotes the synergistic effects between PEO and PMMA. The EIS result revealed that the conductivity of the electrolytes increases with LiClO4 concentration in PEO/PMMA blends, but it increases at first and reaches maximum value of 2.53 × 10−4 S/cm at 1.0 % of LCI. The addition of 1.0 % LCI increases the conductivity of the electrolytes due to that LCl promoting compatibility and interaction of PEO and PMMA. Under the combined action of rigidity induced crystal unit, soft segment and the terminal ionic groups in LCI, PEO/PMMA interfacial interaction are improved, the reduction of crystallinity degree of PEO leads Li+ migration more freely.

Novel fluorescent main-chain liquid crystalline ionomers containing Eu(III) ions

ABSTRACTNovel nematic fluorescent main-chain liquid crystalline ionomers containing Eu(III) ions (Eu-LCI) were synthesised by the use of bis(4-(chlorocarbonyl)phenyl) decanedioate (BD), 4,4-dihydroxybiphenyl (D), 2,5-dihydroxybenzoic acid (B) and anhydrous europium chloride. The chemical structures, liquid crystalline behaviours and fluorescence properties of Eu-LCI were characterised by various experimental techniques. The introduction of small amounts of europium ions endowed the LCI with excellent luminescence properties. POM results showed that europium ions did not change the liquid crystalline texture of the LCI. Fourier transform infrared imaging showed that europium ions were evenly distributed in the matrices of ionomers. A schematic diagram of nematic fluorescent LCI was established to demonstrate the interaction and distribution of the components. Eu-LCI showed reversible mesomorphic phase transitions, wide mesophase temperature ranges and high thermal stability. The thermogravimetric analysis (TGA) results showed that decomposition temperatures (5% weight loss) were greater than 308°C in all Eu-LCI. Eu-LCI can emit red light when excited. The luminescence intensity of Eu-LCI gradually increased with increase in Eu(III) ions from 0.3 to 1.5 mol%. The temperature dependence of luminescent intensity was studied in the liquid crystalline phase, where the fluorescence intensity of Eu-LCI decreased monotonically with increase in temperature.

Synthesis and characterization of liquid-crystalline ionomers with pendant cholesteryl pyridinium salt mesogens

Novel pyridinium-based liquid-crystalline ionomers were synthesized, which showed various mesophases due to the ion aggregations of ionic mesogens.

Morphology and Mechanical Properties of Ternary Polymer Blends Containing Liquid Crystalline Ionomers with Different Ionic Group

Three side-chain liquid crystalline ionomers (SLCIs) with sulfonic group (SLCI-S), quaternary ammonium salt group (SLCI-N), and carboxylic group (SLCI-C) were synthesized by graft copolymerization upon polymethylhydrosiloxane, respectively. The SLCIs were used to blend with poly (butylene terephthalate) (PBT) and polypropylene (PP). The morphological structure and mechanical properties of the blends were investigated by scanning electron microscopy (SEM). SEM results indicated that the addition of SLCIs lead to finer and better dispersion of PP polymer in the blends relative to the blends with no SLCIs added. The compatibilization of SLCIs in the blends were in the increasing order of SLCI-S> SLCI-N> SLCI-C, which was due to the specify interaction between SLCIs and PBT increased with the increasing order of SLCI-S>SLCI-N>SLCI-C. The mechanical properties were improved when the proper amount of SLCI was added, which enabled improve adhesion at the interface. The mechanical property of PBT/PP/SLCI-S was higher than that of PBT/PP/SLCI-N, which was higher than that of PBT/PP/SLCI-C.

Main-chain liquid crystalline ionomers with a nonplanar ionic segment

At the presence of the physical crosslinking of ionic groups, tensile properties of the liquid crystalline ionomer were improved greatly.

Preparation and thermal properties of liquid crystalline ionomers having mesogenic ester side chains containing three phenyl groups

A series of liquid crystalline (LC) copolymers having both the repeat units of mesogenic ester side chains containing three phenyl groups and the repeat units possessing an acid group were prepared. The acid groups of the LC copolymers were neutralized with sodium acetate to give a varying degree of neutralization. It was found that the LC properties of the ionomers depended strongly on both the relative amount of the units having the mesogenic side chains and the amount of ionic units. It was also observed that the formation of the nematic phase of the LC ionomers was suppressed by the increase in ion contents. After the analysis of the thermal data of the phase transitions, it was suggested that the transition temperatures of the LC phases of the copolymers and their ionomer forms, and the temperature ranges for the LC phases were affected by the relative amounts of both mesogenic and acidic units and by the degree of neutralization, simultaneously.

Synthesis, structure, and mesomorphic properties of main-chain liquid-crystalline ionomers containing sulfonate groups

The mesogenic monomer M and a series of main-chain liquid crystalline ionomers (LCIs) containing sulfonate groups were synthesized. The LCIs were prepared by an interfacial condensation reaction of mesogenic monomer 1,4-phenylene-dicarbonic acid bis (4-carboxyl phenyl) ester, brittle yellow (BY), 1,10-sebacoyl dihydroxy, and 1,12-dodecanedioyl dihydroxy. The sulfonate groups introduced to the main-chain backbone were confirmed by ultraviolet spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry (DSC), thermo gravimetric (TG), and polarizing optical microscopy (POM). Experimental results demonstrated that the glass-transition temperatures increased slightly, melting temperature decreased, and the mesophase temperature ranges increased first and then decreased with increasing content of sulfonate group. All of the polymers were thermally stable up to 320 °C. The LCIns exhibited typical nematic schlieren textures.

Miscibility enhancement of PP/PBT blends with a side‐chain liquid crystalline ionomer

AbstractSide‐chain liquid crystalline ionomer (SLCI) containing sulfonic acid groups with a polymethylhydrosiloxane main‐chain was used in the blends of polypropylene (PP) and polybutylene terephthalate (PBT) as a compatibilizer. The crystalline behavior, morphological, and mechanical properties of the blends were investigated in detail by differential scanning calorimetry (DSC), polarizing optical microscope (POM), Fourier transforms infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Revealed by the shift of Tm in DSC thermogram and the shift of the absorbed peak in FTIR spectra, specific interaction led to stronger interfacial adhesion between these phases, which resulted in much finer dispersion of the minor PBT phase in PP matrix. The SLCI containing sulfonate acid groups acted as physical crosslinking agent along the interface, which compatibilized PP/PBT blends. The mechanical property of the blends including 4 wt % SLCI contents was better than that of other SLCI contents in the blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Local modes of molecular mobility in comb-shaped liquid crystalline ionomers containing alkaline metal ions

Molecular mobility of the comb-shaped copolymer poly(4-[6-(acryloyloxy)hexyloxy]benzoic acid- co-butyl acrylate) and Li- and Rb-containing LC ionomers based on this polymer was studied at low temperatures by the methods of dielectric spectroscopy and thermally stimulated depolarization current. The above copolymers are shown to experience the γ 2, γ 1, and β-processes, which are related by the reorientation of the end СООН groups, by the mobility of a spacer, and by the reorientation of mesogenic fragments (dimers of oxybenzoic acids) with respect to a long axis, respectively. The formation of multiplet structures in ionomers leads to a suppression of the intensity of the β-process that relates with a partial breakdown of hydrogen-bonded dimmers and with a decrease of their molecular mobility.

Synthesis and mesomorphic properties of side‐chain liquid crystalline ionomers containing sulfonic acid groups

AbstractSide‐chain liquid crystalline ionomers containing M1 (4‐allyoxybenzoyloxy‐4′‐amylbenzoyloxy biphenyl) as mesogenic units and M2 (4‐undecylenicoxy‐4′‐phenylazobenzene sulfonic acid) as ionic units were synthesized by graft copolymerization. Their liquid crystalline properties were characterized by differential scanning calorimetry, polarizing optical microscopy, and X‐ray diffraction measurements. The results showed that introduction of nonmesogenic ionic units into polymeric structure could cause additional reduction of the clearing point of the ionomers, compared with the corresponding nonion polymers. When the content of ionic units increased to 8.5%, the ionic clusters and mesogens in the ionomers may be dispersed each other to form multiple blocks, but the introduction of ionic groups in LCIs did not change their mesogenic type. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 304–309, 2007

Thermal, morphological, and mechanical characteristics of polypropylene/polybutylene terephthalate blends with a liquid crystalline polymer or ionomer

AbstractThermotropic side‐chain liquid crystalline polymer (SLCP) and corresponding side‐chain liquid crystalline ionomer (SLCI) containing sulfonate acid were used in the blends of polypropylene (PP) and polybutylene terephthalate (PBT) by melt‐mixing respectively, and thermal behavior, morphological, and mechanical properties of two series of blends were investigated by differential scanning calorimetry, Fourier transforms infrared spectroscopy (FTIR), scanning electron microscopy, and tensile measurement. Compared with the immiscible phase behavior of PP/PBT/SLCP blends, SLCI containing sulfonate acid groups act as a physical compatibilizer along the interface and compatibilize PP/PBT blends. FTIR analyses identify specific intermolecular interaction between sulfonate acid groups and PBT, and then result in stronger interfacial adhesion between these phases and much finer dispersion of minor PBT phase in PP matrix. The mechanical property of the blend containing 4.0 wt % SLCI was better than that of the other blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4712–4719, 2006

Liquid‐Crystalline Ionomers as a New Class of Mesomorphous Polymeric Systems

AbstractFor Abstract see ChemInform Abstract in Full Text.

Main‐chain chiral smectic liquid‐crystalline ionomers containing sulfonic acid groups

AbstractThree series of main‐chain liquid‐crystalline polymers (P1, P2, and P3) were synthesized by an interfacial condensation reaction of sebacoyl dichloride with various amount of brilliant yellow, isosorbide, and 4,4′‐biphenydiol. P1 series are polyesters prepared from sebacoyl chloride and various amount of 4,4′‐biphenyldiol and isosorbide. P2 series are polyesters prepared from sebacoyl chloride and various amount of 4,4′‐biphenyldiol, brilliant yellow, and isosorbide. P3 series are polyesters prepared from sebacoyl chloride and various amount of 4,4′‐biphenyldiol and brilliant yellow. P2 and P3 are main‐chain liquid‐crystalline ionomers. P12 and P3 series were prepared as model polymers for comparison with the liquid crystalline behavior of ionomers, P2 series. The structures of the polymers were characterized by IR and UV spectroscopy. Differential scanning calorimetry was used to measure the thermal properties of the polymers. The mesogenic properties were investigated by polarized optical microscope, differential scanning calorimetry, and X‐ray diffraction measurements. The results show that P2 series are chiral smectic C (SmC*) and chiral smectic B (SmB*) liquid crystalline ionomers exhibiting broken focal‐conic texture and schlieren, as is the polymer P12, which has the same amount of 4,4′‐biphenydiol and isosorbide. The introduction of ionic units in P2 series leads to an increase of clearing point, but has not affected the mesogenic type and texture, as compared with the corresponding polymer P12. The introduction of chiral units in P2 series leads to a change of mesophase, as compared with P3 series, which exhibit smectic C mesogetic phase. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1254–1263, 2006

Synthesis and characterization of main chain liquid crystalline ionomers containing sulphonate groups

A series of main chain liquid crystalline ionomers containing sulphonate groups pendent to the polymer backbone were synthesized by an interfacial condensation reaction of 4,4′‐bis(1,10‐sebacyloxo)benzoic acid, brilliant yellow (BY), and 4,4′‐biphenyldiol. 4,4′‐Bis(1,10‐sebacyloxo)benzoic acid exhibited nematic schlieren texture during heating and cooling. The ionomers are thermotropic liquid crystalline polymers and thermally stable to about 270°C. They exhibit broad mesophase regions over a range of 220°C and the same nematic mesomogen with a colourful thread texture as B0‐LCP, which implies that the introduction of an ionic group did not change the texture of the B0‐LCP. However, the thermotropic liquid crystalline properties were somewhat weakened when the concentration of BY was more than 5%. The inherent viscosity in N,N‐dimethylformamide solution suggested that intermolecular associations of sulphonate groups occurred at low concentration, and intermolecular associations predominated at higher concentration.

Dielectric Relaxation of Side-Chain Liquid Crystalline Ionomers Containing Alkaline Metal Ions

Summary: Two sets of side-chain, liquid-crystalline ionomers based on copolymers of butyl acrylate and 4-{[6-(acryloyloxy)hexyl]oxy}benzoic acid containing 2.5–20 mol-% of lithium or rubidium ions were studied. As the content of ions of alkali metals increases, segmental mobility markedly decreases. As compared with rubidium-containing ionomers, ionomers containing lithium ions are characterized by a far more efficient decrease in their dielectric relaxation times because ionic radius of lithium ions is lower than that of rubidium ions.

Liquid Crystalline Ionomers Containing Azobenzene Mesogens: Phase Stability, Photoinduced Birefringence, and Holographic Grating

Liquid crystalline (LC) ionomers containing azobenzene mesogens and three transition metal ions (Cu2+, Zn2+, and Mn2+) were prepared and characterized. Metal ions were found to exert significant effects on the photoinduced orientation of azobenzene mesogens and on the diffraction efficiency of holographic gratings. Using methacrylic acid for neutralization with metal ions, as compared with the copolymer with no metal, ionomers of Zn and Mn showed increased photoinduced birefringence and higher diffraction efficiency of birefringence gratings obtained by excitation with spatially modulated light polarization. By contrast, ionomers with Cu showed the opposite effects. As a whole, the behavior of photoinduced birefringence and holographic grating appears to be correlated with the thermal stability of the LC phase formed by azobenzene mesogens in the ionomer. Some new thoughts are discussed regarding the effect of metal and their ionic aggregates on the clearing temperature of LC ionomers. The interest for fu...

Synthesis and properties of side chain liquid crystalline ionomers containing quaternary ammonium salt groups

New thermotropic side chain liquid crystalline ionomers (LCIs), containing 4-(4-allyloxybenzyloxy)-4′-alkoxybiphenyl (IM) as mesogenic unit and allyltriethylammonium bromide (ATAB) as non-mesogenic unit, were synthesized by graft copolymerization upon polymethylhydrosiloxane. The chemical structures of the polymers were confirmed by IR spectroscopy. Differential scanning calorimetry (DSC) was used to measure the thermal properties of these polymers; the mesogenic properties were characterized by polarizing optical micrography, DSC and X-ray diffraction. The influence of the alkoxy chain length on the clearing temperatures of the ionomers is clearly shown in an odd–even effect, similar to other side chain liquid crystal polymers. The mesomorphic behaviour of the ionomers is compared with that of isomeric ionomers synthesized in previous work. The results demonstrate that the phase behaviour of the two series of isomeric ionomers is similar, but with the difference that the melting temperature of ionomers with biphenyl located at the end of the mesogen is higher than for ionomers with biphenyl located at the middle of the mesogen. The latter are more useful for smectic orientational order than the former.

Molecular mobility of CU(II)-containing liquid crystalline ionomers: dielectric relaxation and thermally stimulated depolarization currents

Molecular mobility of CU(II)-containing liquid crystalline ionomers: dielectric relaxation and thermally stimulated depolarization currents

Molecular mobility of CU(II)-containing liquid crystalline ionomers: dielectric relaxation and thermally stimulated depolarization currents

Molecular mobility of functionalized liquid crystalline (LC) copolymer (P1) containing mesogenic cyanobiphenyl groups and acrylic acid fragments (28%) as well as LC ionomers P2 (Cu 2.5() and P3 (Cu 7() with copper ions were studied by dielectric spectroscopy (DS) and by thermally stimulated depolarization current (TSDC) methods. For P1–P3, the frequency dependences of dielectric losses and temperature dependences of depolarization current were obtained and four relaxation processes γ1, β, α, and δ were found. For each of them a molecular mechanism was proposed. Moreover, for P1, P2, and P3, at high temperatures the TSDC global curves indicate the peak of depolarization current, which has no analogue in the dielectric spectrum. For P1 this peak is a ρ-process of low intensity. For P2 and P3 ionomers the intensity and temperature position of the high temperature peak increase as compared to those of P1. The mechanisms of the high temperatures peak for the P2 and P3 systems containing copper ions were attributed to the free space charge polarization and to the dipole polarization process of polymer chains included in ionic associates (multiplets). There is good correlation between the peak temperature positions obtained from the global TSDC spectrum at equivalent frequency and those obtained from DS.

Synthesis and characterization of side‐chain liquid‐crystalline ionomers containing quaternary ammonium salt groups

AbstractA series of thermotropic side‐chain liquid‐crystalline ionomers (LCIs) containing 4‐(4‐alkoxybenzyloxy)‐4′‐allyloxybiphenyl (M) as mesogenic units and allyl triethylammonium bromide (ATAB) as nonmesogenic units were synthesized by graft copolymerization upon polymethylhydrosiloxane. The chemical structures of the polymers were confirmed by IR spectroscopy. DSC was used to measure the thermal properties of these polymers. The mesogenic properties were characterized by polarizing optical microscopy, DSC, and X‐ray diffraction. Homopolymers without ionic groups exhibit smectic and nematic mesophases. The nematic mesophases of the ionomers disappear and the mesomorphic temperature ranges decrease with increasing concentration of ionic units. The influence of the alkoxy chain length on clearing temperature (Tc) values of ionomers clearly shows an odd‐even effect, similar to that of other side‐chain liquid‐crystalline polymers. The mesomorphic temperature ranges increase with increasing alkoxy chain length when the number of alkoxy carbon is over 3. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2879–2886, 2003