Ewa Schab-balcerzak - Academia.edu (original) (raw)

Papers by Ewa Schab-balcerzak

Research paper thumbnail of Polyazomethine with vinylene and phenantridine moieties in the main chain: Synthesis, characterization, opto(electrical) properties and theoretical calculations

High Performance Polymers

The opto(electrical) properties and theoretical calculations of polyazomethine with vinylene and ... more The opto(electrical) properties and theoretical calculations of polyazomethine with vinylene and phenantridine moieties in the main chain were investigated in the present study. 2,5-Bis(hexyloxy)-1,4-bis[(2,5-bis(hexyloxy)-4-formyl-phenylenevinylen e]benzene was polymerized in solution with 3,8-diamino-6-phenylphenanthridine (PAZ-PV-Ph). The temperatures of 5% weight loss (T-5%) of the polyazomethine was observed at 356 degrees C in nitrogen. Electrochemical properties of thin film of the polymer were studied by differential pulse voltammetry. The HOMO level of the PAZ-PV-Ph was at -4.97 eV. The energy band gap (E-g) was detected of approximately similar to 1.9 eV. Energy band gap (E-gopt) was additionally calculated from absorption spectrum and absorption coefficient alpha. The absorption UV-vis spectra of polyazomethine recorded in solution showed a blue shift in comparison with the solid state. HOMO-LUMO levels and E-g were additionally calculated theoretically by density functio...

Research paper thumbnail of Investigation of optical and electrical properties of new aromatic polyazomethine with thiophene and cardo moieties toward application in organic solar cells

Synthetic Metals

New polyazomethine (25Th-cardo) based on thiophene and cardo moieties was synthesized, characteri... more New polyazomethine (25Th-cardo) based on thiophene and cardo moieties was synthesized, characterized and tested as active layer in solar cells. The structure of polymer was characterized by means of FTIR and 1H NMR spectroscopy. The temperatures of 5% weight loss of the polyazomethine range from 435 to 455 °C in nitrogen, depending on the heating rate applied. 25Th-cardo has electrochemical energy band gap of approximately ∼1.85 eV, and HOMO energy level at −5.21 eV. Optical absorption properties of pure 25Th-cardo and of its mixtures with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were investigated on different substrates: glass or glass/PEDOT:PSS. Electrical properties of the two kinds of devices: ITO/25Th-cardo:PCBM/Al and ITO/PEDOT:PSS/25Th-cardo:PCBM/Al were tested by impedance spectroscopy. The investigated polymer solar cells contained different amounts of PCBM. Bulk heterojunction solar cells with the architecture ITO/PEDOT:PSS/25Th-cardo:PCBM/Al gave a power conversi...

Research paper thumbnail of Characterization, liquid crystalline behavior, electrochemical and optoelectrical properties of new poly(azomethine)s and a poly(imide) with siloxane linkages

Research paper thumbnail of Novel soluble aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties: characterization and optical properties

Research paper thumbnail of New aliphatic–aromatic tetraphenylphthalic-based diimides: Thermal, optical and electrical study

Research paper thumbnail of New conjugated polyimides with special architecture: Photoluminescence of violet, blue and green polyimides in solution and in blend with poly(methylmethacrylate)

Tuning the chemical structure, band gap of conjugated polymers and designing LEDs emitting select... more Tuning the chemical structure, band gap of conjugated polymers and designing LEDs emitting selected colors remains a challenging issue. In our work three strategies were reported for tuning the emission color of aromatic polyimides: (i) changing the main chain molecular structure, (ii) blending a light emitting polymer with another nonemissive polymer such as poly(methylmethacrylate) (PMMA) and (iii) doping. Additionally, in this paper we present the effect of excitation wavelength, concentration, film thickness and kind of solvent on the photoluminescence (PL) properties of the polyimides. New conjugated polyimides, i.e. polymers containing cyclic imide and aromatic groups in the main chain, were synthesized from four different diamines and five different dianhydrides via polycondensation with the goal to obtain new materials with tunable luminescent properties. The following commercial diamines 2,7-diaminofluorene (DAF), 2,4-diamino-6-phenyl-1,3,5-triazine (DAPT), 4,4'-methyle...

Research paper thumbnail of Optical, electrical and mechanical properties of indium tin oxide on polyethylene terephthalate substrates: Application in bulk-heterojunction polymer solar cells

Materials Science in Semiconductor Processing

We investigated optical, electrical and mechanical properties of indium tin oxide (ITO) on flexib... more We investigated optical, electrical and mechanical properties of indium tin oxide (ITO) on flexible polyethylene terephthalate (PET) substrate, considering bulk-heterojunction (BHJ) polymer solar cells applications. Encapsulation of flexible solar cells with the architecture PET/ITO/PEDOT:PSS/P3HT:PCBM (or P3HT:PCBM:AZ-NDI-4)/Al was done by direct brush-painting with nail enamel. Active cell layer blends of [6,6]-phenyl C61 butyric acid methyl ester (PCBM) with regioregular or regiorandom poly(3-hexylthiophene-2,5-diyl) (P3HT) were applied. Additionally for this role the mixture of regioregular P3HT:PCBM with naphthalene diimide–imine with four thiophene rings AZ-NDI-4 was tested. Obtained photovoltaic (PV) and optical (UV–vis) results of the flexible polymer solar cells were compared with the same architecture of devices on the glass/ITO substrate.

Research paper thumbnail of Spectral, electrochemical and thermal characteristics of glass forming hydrazine derivatives

Research paper thumbnail of Characterization, liquid crystalline behavior, optical and electrochemical study of new aliphatic–aromatic polyimide with naphthalene and perylene subunits

Research paper thumbnail of New semiladder polymers: III. Synthesis and properties of new poly(etherimidazopyrrolone)s

Research paper thumbnail of Epoxy resin cured with diamine bearing azobenzene group

Research paper thumbnail of New azomethine-phthalic diimides: Synthesis and thermal, optical and electrochemical characterization

Synthetic Metals, 2013

ABSTRACT A new diamine with phthalic diimide moiety, i.e. N,N′-bis(4-amino-2,3,5,6-tetramethylphe... more ABSTRACT A new diamine with phthalic diimide moiety, i.e. N,N′-bis(4-amino-2,3,5,6-tetramethylphenyl)phthalene-1,4-dicarboxyimide was synthesized and applied for condensation with 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde and 4-octadecyloxybenzaldehyde, which resulted in two new azomethine-phthalic diimides (AZ-PDIs). Thermal, optical and electrochemical properties of AZ-PDIs were discussed in relation to their analogous containing instead of five-membered six-membered imide rings (AZ-NDIs) described in our previous work. The phase behavior of AZ-PDIs examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) confirms their liquid crystalline properties in wide range of temperatures. AZ-PDIs do not show decomposition below 400 °C as was found based on thermogravimetric analyses (TGA). Optical properties of the prepared compounds were investigated by UV–vis and photoluminescence (PL) measurements. Azomethine-phthalic diimides emitted blue light with emission maximum (λem) at ca. 446–492 nm contrary to azomethine-naphthalene diimides which emitted green light and λem was at 536 and 540 nm. The obtained compounds are electrochemically active and undergo reversible reduction and oxidation as evidenced by differential pulse voltammetry (DPV). The azomethine-phthalic diimides exhibited low electrochemical band gap ca. 1.68 eV being promising for optoelectronic applications.

Research paper thumbnail of New semiladder polymers. Part II: Synthesis and properties of new poly(amideimidazopyrrolones)

Polymer, 1999

A series of polymers from new diamidedianhydrides of arylene-di(benzene-5-amido-1,2-dicarboxylic)... more A series of polymers from new diamidedianhydrides of arylene-di(benzene-5-amido-1,2-dicarboxylic) anhydride type and aromatic tetraamines (3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenylether) were synthesized using one step high temperature polycondensation in m-cresol and p-chlorophenol at 180°C and low temperature polycondensation. The polymers had a semiladder structure. The influence of the monomer structure and polycondensation method on the polymer properties has been investigated.

Research paper thumbnail of New Polyimides as Precursors for Functionalized Polymers

High Performance Polymers, 2001

A series of copolymers from 3,3′,4,4′-benzophenonetetracarboxylic di-anhydride and 3,3′,4,4′-biph... more A series of copolymers from 3,3′,4,4′-benzophenonetetracarboxylic di-anhydride and 3,3′,4,4′-biphenyltetracarboxylic dianhydride and two diamines, 4,4′-diaminodiphenylether and 3,5-diaminobenzoic acid, were synthesized. The influence of various ratios of diamines on the properties of polymers were investigated. A preliminary study on the potential of using the carboxylic acid group for substitution was carried out.

Research paper thumbnail of Structure–Properties Relationship of Some Polyimidazopyrrolones Foils

High Performance Polymers, 2001

A series of semiladder polyimidazopyrrolones having amide, ester and ether linkages in the main c... more A series of semiladder polyimidazopyrrolones having amide, ester and ether linkages in the main chain have been synthesized using low-temperature polycondensation in dimethylacetamide (DMA). Solutions of prepolymers in the form of proper polyamideamino acid in DMA were cast onto a glass plate, heated in vacuo at 200 °C for 8 h and then at 280 °C for 2 h to

Research paper thumbnail of <title>Optically induced gratings in azo-functionalized polymers studied by a moving grating technique</title>

Organic Photonic Materials and Devices VII, 2005

Light-induced optical anisotropy have been studied by laser grating inscription method within the... more Light-induced optical anisotropy have been studied by laser grating inscription method within the group of novel azobenzene functionalized polymers. Undergoing light-induced trans-cis-trans photoisomerisations azo-benzene groups were covalently bonded to the ...

Research paper thumbnail of Electronic and thermal properties of compounds bearing diimide, azomethine and triphenylamine units

Optical Materials, 2014

ABSTRACT New triphenylamine containing azomethine diimides and two kinds of poly(azomethine imide... more ABSTRACT New triphenylamine containing azomethine diimides and two kinds of poly(azomethine imide)s, i.e., linear and branched were synthesized. These compounds were prepared from two diamines, that is, N,N′-bis(4-amino-2,3,5,6-tetramethylphenyl)phtalene-1,2,4,5-dicarboximide (DAPhDI), N,N′-bis(5-aminonaphtalen)naphthalene-1,4,5,8-dicarboxyimide (DANDI-2) and 4-formyltriphenylamine, 4,4′-diformyltriphenylamine and 4,4′,4″-triformyltriphenylamine. The structures of the compounds were characterized by means of FTIR, 1H NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. Thermal properties of prepared azomethine diimides and polymers were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Obtained compounds exhibited high thermal stability with 5% weight-loss temperatures above 390 °C. Azomethine diimides exhibited glass-forming properties with high glass-transition temperatures 216 and 308 °C. Optical properties of the prepared compounds were investigated by UV–vis and photoluminescence (PL) measurements. All compounds emitted blue light in NMP solution and in solid state as blend with PMMA. The electrochemical properties, that is, orbital energies and resulting energy gap were estimated based on cyclic voltammetry (CV). All synthesized material showed reversible reduction process, furthermore AzPhDI and AzNDI showed partially reversible oxidation process. Electrochemical band gap was found in the range 1.23–1.70 eV. Low molecular weight model compounds were tested as bipolar host materials in blue phosphorescent organic light emitting diodes (OLEDs). The devices exhibited turn-on voltages of about 5.5 V and maximum brightness of 40–220 cd/m2.

Research paper thumbnail of Poly(etherimide)s and poly(esterimide)s containing azobenzene units: Characterization and study of photoinduced optical anisotropy

Optical Materials, 2012

In this paper novel processable, photoresponsible aromatic polymers with imide rings and covalent... more In this paper novel processable, photoresponsible aromatic polymers with imide rings and covalently boned azobenzene units are presented. Prepolymerization strategy based on polycondensation of two diamines with azobenzene group, that is, 2,4-diamino-4′-cyanoazobenzne and 2,4-diamino-4′-nitroazobenzene and two dianhydrides, was utilized for preparation of the new photochromic polyimides. The obtained polymers differ in the chemical structure of polymer backbone and the kind

Research paper thumbnail of Photophysical, electrochemical and thermal properties of new (co)polyimides incorporating oxadiazole moieties

Synthetic Metals, 2014

ABSTRACT New polyimides and copolyimides were obtained by polycondensation of 2,5-bis(p-aminophen... more ABSTRACT New polyimides and copolyimides were obtained by polycondensation of 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole with one of the three aromatic dianhydrides: 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) and 4,4′-tetraphthaloyl-bis(1,8-naphthalene dicarboxylic)dianhydride. The photophysical properties such as UV absorption, photoluminescence (PL), electrochemical and spectroelectrochemical properties of the copolymers were evaluated. Additionally, their thermal behavior was investigated. The polymers dissolved in NMP and in the solid state as blend with nonemissive poly(methyl methacrylate) emitted blue light with the highest intensity under excitation wavelength (λex) 340 nm, whereas, under λex = 405 nm green fluorescence was observed with double-exponential lifetime. Longer decay constants were estimated for polymers in blend as compared with the ones obtained for solutions. The electronic properties, such as, HOMO–LUMO levels and band gaps were calculated via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) and for models of polyimides were calculated theoretically by density functional theory (DFT). All of the polymers exhibited reversible reduction and non-reversible oxidation process. The electrochemical band gaps based on DPV measurements were in the range of 1.79–2.50 eV. Spectral changes in UV–vis region under applied potential were observed. Decreasing of applied potential to negative values resulted in appearance of new band around 600 nm in the case of film prepared from polyimide with naphthalene imide rings and with copolyimide containing naphthalene diimide and phthalic imide structures. The obtained polymers exhibited glass transition temperatures (Tg) in the range of 227–336 °C and decomposition temperature (Td) in the range of 382–505 °C.

Research paper thumbnail of New polyamides with azo-chromophore groups

Thin Solid Films, 2004

A series of four novel polyamides with semiflexible main chains were prepared from two azo-chromo... more A series of four novel polyamides with semiflexible main chains were prepared from two azo-chromophore diamines: 2,4-diamino-4′-nitroazobenzene and 2,4-diamino-4-azo-(4′-nitroazobenzene)benzene. Polymers were obtained from diacid chlorides by the polycondensation reaction in DMA solution. The polymers were identified by infrared, 1H NMR spectroscopy and elemental analysis. The thermal properties of these polymers were investigated using differential scanning calorimetry (DSC) method and thermogravimetric

Research paper thumbnail of Polyazomethine with vinylene and phenantridine moieties in the main chain: Synthesis, characterization, opto(electrical) properties and theoretical calculations

High Performance Polymers

The opto(electrical) properties and theoretical calculations of polyazomethine with vinylene and ... more The opto(electrical) properties and theoretical calculations of polyazomethine with vinylene and phenantridine moieties in the main chain were investigated in the present study. 2,5-Bis(hexyloxy)-1,4-bis[(2,5-bis(hexyloxy)-4-formyl-phenylenevinylen e]benzene was polymerized in solution with 3,8-diamino-6-phenylphenanthridine (PAZ-PV-Ph). The temperatures of 5% weight loss (T-5%) of the polyazomethine was observed at 356 degrees C in nitrogen. Electrochemical properties of thin film of the polymer were studied by differential pulse voltammetry. The HOMO level of the PAZ-PV-Ph was at -4.97 eV. The energy band gap (E-g) was detected of approximately similar to 1.9 eV. Energy band gap (E-gopt) was additionally calculated from absorption spectrum and absorption coefficient alpha. The absorption UV-vis spectra of polyazomethine recorded in solution showed a blue shift in comparison with the solid state. HOMO-LUMO levels and E-g were additionally calculated theoretically by density functio...

Research paper thumbnail of Investigation of optical and electrical properties of new aromatic polyazomethine with thiophene and cardo moieties toward application in organic solar cells

Synthetic Metals

New polyazomethine (25Th-cardo) based on thiophene and cardo moieties was synthesized, characteri... more New polyazomethine (25Th-cardo) based on thiophene and cardo moieties was synthesized, characterized and tested as active layer in solar cells. The structure of polymer was characterized by means of FTIR and 1H NMR spectroscopy. The temperatures of 5% weight loss of the polyazomethine range from 435 to 455 °C in nitrogen, depending on the heating rate applied. 25Th-cardo has electrochemical energy band gap of approximately ∼1.85 eV, and HOMO energy level at −5.21 eV. Optical absorption properties of pure 25Th-cardo and of its mixtures with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were investigated on different substrates: glass or glass/PEDOT:PSS. Electrical properties of the two kinds of devices: ITO/25Th-cardo:PCBM/Al and ITO/PEDOT:PSS/25Th-cardo:PCBM/Al were tested by impedance spectroscopy. The investigated polymer solar cells contained different amounts of PCBM. Bulk heterojunction solar cells with the architecture ITO/PEDOT:PSS/25Th-cardo:PCBM/Al gave a power conversi...

Research paper thumbnail of Characterization, liquid crystalline behavior, electrochemical and optoelectrical properties of new poly(azomethine)s and a poly(imide) with siloxane linkages

Research paper thumbnail of Novel soluble aromatic poly(amideimide)s containing 9,9-diphenylfluorene moieties: characterization and optical properties

Research paper thumbnail of New aliphatic–aromatic tetraphenylphthalic-based diimides: Thermal, optical and electrical study

Research paper thumbnail of New conjugated polyimides with special architecture: Photoluminescence of violet, blue and green polyimides in solution and in blend with poly(methylmethacrylate)

Tuning the chemical structure, band gap of conjugated polymers and designing LEDs emitting select... more Tuning the chemical structure, band gap of conjugated polymers and designing LEDs emitting selected colors remains a challenging issue. In our work three strategies were reported for tuning the emission color of aromatic polyimides: (i) changing the main chain molecular structure, (ii) blending a light emitting polymer with another nonemissive polymer such as poly(methylmethacrylate) (PMMA) and (iii) doping. Additionally, in this paper we present the effect of excitation wavelength, concentration, film thickness and kind of solvent on the photoluminescence (PL) properties of the polyimides. New conjugated polyimides, i.e. polymers containing cyclic imide and aromatic groups in the main chain, were synthesized from four different diamines and five different dianhydrides via polycondensation with the goal to obtain new materials with tunable luminescent properties. The following commercial diamines 2,7-diaminofluorene (DAF), 2,4-diamino-6-phenyl-1,3,5-triazine (DAPT), 4,4'-methyle...

Research paper thumbnail of Optical, electrical and mechanical properties of indium tin oxide on polyethylene terephthalate substrates: Application in bulk-heterojunction polymer solar cells

Materials Science in Semiconductor Processing

We investigated optical, electrical and mechanical properties of indium tin oxide (ITO) on flexib... more We investigated optical, electrical and mechanical properties of indium tin oxide (ITO) on flexible polyethylene terephthalate (PET) substrate, considering bulk-heterojunction (BHJ) polymer solar cells applications. Encapsulation of flexible solar cells with the architecture PET/ITO/PEDOT:PSS/P3HT:PCBM (or P3HT:PCBM:AZ-NDI-4)/Al was done by direct brush-painting with nail enamel. Active cell layer blends of [6,6]-phenyl C61 butyric acid methyl ester (PCBM) with regioregular or regiorandom poly(3-hexylthiophene-2,5-diyl) (P3HT) were applied. Additionally for this role the mixture of regioregular P3HT:PCBM with naphthalene diimide–imine with four thiophene rings AZ-NDI-4 was tested. Obtained photovoltaic (PV) and optical (UV–vis) results of the flexible polymer solar cells were compared with the same architecture of devices on the glass/ITO substrate.

Research paper thumbnail of Spectral, electrochemical and thermal characteristics of glass forming hydrazine derivatives

Research paper thumbnail of Characterization, liquid crystalline behavior, optical and electrochemical study of new aliphatic–aromatic polyimide with naphthalene and perylene subunits

Research paper thumbnail of New semiladder polymers: III. Synthesis and properties of new poly(etherimidazopyrrolone)s

Research paper thumbnail of Epoxy resin cured with diamine bearing azobenzene group

Research paper thumbnail of New azomethine-phthalic diimides: Synthesis and thermal, optical and electrochemical characterization

Synthetic Metals, 2013

ABSTRACT A new diamine with phthalic diimide moiety, i.e. N,N′-bis(4-amino-2,3,5,6-tetramethylphe... more ABSTRACT A new diamine with phthalic diimide moiety, i.e. N,N′-bis(4-amino-2,3,5,6-tetramethylphenyl)phthalene-1,4-dicarboxyimide was synthesized and applied for condensation with 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde and 4-octadecyloxybenzaldehyde, which resulted in two new azomethine-phthalic diimides (AZ-PDIs). Thermal, optical and electrochemical properties of AZ-PDIs were discussed in relation to their analogous containing instead of five-membered six-membered imide rings (AZ-NDIs) described in our previous work. The phase behavior of AZ-PDIs examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM) confirms their liquid crystalline properties in wide range of temperatures. AZ-PDIs do not show decomposition below 400 °C as was found based on thermogravimetric analyses (TGA). Optical properties of the prepared compounds were investigated by UV–vis and photoluminescence (PL) measurements. Azomethine-phthalic diimides emitted blue light with emission maximum (λem) at ca. 446–492 nm contrary to azomethine-naphthalene diimides which emitted green light and λem was at 536 and 540 nm. The obtained compounds are electrochemically active and undergo reversible reduction and oxidation as evidenced by differential pulse voltammetry (DPV). The azomethine-phthalic diimides exhibited low electrochemical band gap ca. 1.68 eV being promising for optoelectronic applications.

Research paper thumbnail of New semiladder polymers. Part II: Synthesis and properties of new poly(amideimidazopyrrolones)

Polymer, 1999

A series of polymers from new diamidedianhydrides of arylene-di(benzene-5-amido-1,2-dicarboxylic)... more A series of polymers from new diamidedianhydrides of arylene-di(benzene-5-amido-1,2-dicarboxylic) anhydride type and aromatic tetraamines (3,3′-diaminobenzidine and 3,3′,4,4′-tetraaminodiphenylether) were synthesized using one step high temperature polycondensation in m-cresol and p-chlorophenol at 180°C and low temperature polycondensation. The polymers had a semiladder structure. The influence of the monomer structure and polycondensation method on the polymer properties has been investigated.

Research paper thumbnail of New Polyimides as Precursors for Functionalized Polymers

High Performance Polymers, 2001

A series of copolymers from 3,3′,4,4′-benzophenonetetracarboxylic di-anhydride and 3,3′,4,4′-biph... more A series of copolymers from 3,3′,4,4′-benzophenonetetracarboxylic di-anhydride and 3,3′,4,4′-biphenyltetracarboxylic dianhydride and two diamines, 4,4′-diaminodiphenylether and 3,5-diaminobenzoic acid, were synthesized. The influence of various ratios of diamines on the properties of polymers were investigated. A preliminary study on the potential of using the carboxylic acid group for substitution was carried out.

Research paper thumbnail of Structure–Properties Relationship of Some Polyimidazopyrrolones Foils

High Performance Polymers, 2001

A series of semiladder polyimidazopyrrolones having amide, ester and ether linkages in the main c... more A series of semiladder polyimidazopyrrolones having amide, ester and ether linkages in the main chain have been synthesized using low-temperature polycondensation in dimethylacetamide (DMA). Solutions of prepolymers in the form of proper polyamideamino acid in DMA were cast onto a glass plate, heated in vacuo at 200 °C for 8 h and then at 280 °C for 2 h to

Research paper thumbnail of <title>Optically induced gratings in azo-functionalized polymers studied by a moving grating technique</title>

Organic Photonic Materials and Devices VII, 2005

Light-induced optical anisotropy have been studied by laser grating inscription method within the... more Light-induced optical anisotropy have been studied by laser grating inscription method within the group of novel azobenzene functionalized polymers. Undergoing light-induced trans-cis-trans photoisomerisations azo-benzene groups were covalently bonded to the ...

Research paper thumbnail of Electronic and thermal properties of compounds bearing diimide, azomethine and triphenylamine units

Optical Materials, 2014

ABSTRACT New triphenylamine containing azomethine diimides and two kinds of poly(azomethine imide... more ABSTRACT New triphenylamine containing azomethine diimides and two kinds of poly(azomethine imide)s, i.e., linear and branched were synthesized. These compounds were prepared from two diamines, that is, N,N′-bis(4-amino-2,3,5,6-tetramethylphenyl)phtalene-1,2,4,5-dicarboximide (DAPhDI), N,N′-bis(5-aminonaphtalen)naphthalene-1,4,5,8-dicarboxyimide (DANDI-2) and 4-formyltriphenylamine, 4,4′-diformyltriphenylamine and 4,4′,4″-triformyltriphenylamine. The structures of the compounds were characterized by means of FTIR, 1H NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. Thermal properties of prepared azomethine diimides and polymers were evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Obtained compounds exhibited high thermal stability with 5% weight-loss temperatures above 390 °C. Azomethine diimides exhibited glass-forming properties with high glass-transition temperatures 216 and 308 °C. Optical properties of the prepared compounds were investigated by UV–vis and photoluminescence (PL) measurements. All compounds emitted blue light in NMP solution and in solid state as blend with PMMA. The electrochemical properties, that is, orbital energies and resulting energy gap were estimated based on cyclic voltammetry (CV). All synthesized material showed reversible reduction process, furthermore AzPhDI and AzNDI showed partially reversible oxidation process. Electrochemical band gap was found in the range 1.23–1.70 eV. Low molecular weight model compounds were tested as bipolar host materials in blue phosphorescent organic light emitting diodes (OLEDs). The devices exhibited turn-on voltages of about 5.5 V and maximum brightness of 40–220 cd/m2.

Research paper thumbnail of Poly(etherimide)s and poly(esterimide)s containing azobenzene units: Characterization and study of photoinduced optical anisotropy

Optical Materials, 2012

In this paper novel processable, photoresponsible aromatic polymers with imide rings and covalent... more In this paper novel processable, photoresponsible aromatic polymers with imide rings and covalently boned azobenzene units are presented. Prepolymerization strategy based on polycondensation of two diamines with azobenzene group, that is, 2,4-diamino-4′-cyanoazobenzne and 2,4-diamino-4′-nitroazobenzene and two dianhydrides, was utilized for preparation of the new photochromic polyimides. The obtained polymers differ in the chemical structure of polymer backbone and the kind

Research paper thumbnail of Photophysical, electrochemical and thermal properties of new (co)polyimides incorporating oxadiazole moieties

Synthetic Metals, 2014

ABSTRACT New polyimides and copolyimides were obtained by polycondensation of 2,5-bis(p-aminophen... more ABSTRACT New polyimides and copolyimides were obtained by polycondensation of 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole with one of the three aromatic dianhydrides: 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-(4,4′-isopropylidene-diphenoxy)bis(phthalic anhydride) and 4,4′-tetraphthaloyl-bis(1,8-naphthalene dicarboxylic)dianhydride. The photophysical properties such as UV absorption, photoluminescence (PL), electrochemical and spectroelectrochemical properties of the copolymers were evaluated. Additionally, their thermal behavior was investigated. The polymers dissolved in NMP and in the solid state as blend with nonemissive poly(methyl methacrylate) emitted blue light with the highest intensity under excitation wavelength (λex) 340 nm, whereas, under λex = 405 nm green fluorescence was observed with double-exponential lifetime. Longer decay constants were estimated for polymers in blend as compared with the ones obtained for solutions. The electronic properties, such as, HOMO–LUMO levels and band gaps were calculated via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) and for models of polyimides were calculated theoretically by density functional theory (DFT). All of the polymers exhibited reversible reduction and non-reversible oxidation process. The electrochemical band gaps based on DPV measurements were in the range of 1.79–2.50 eV. Spectral changes in UV–vis region under applied potential were observed. Decreasing of applied potential to negative values resulted in appearance of new band around 600 nm in the case of film prepared from polyimide with naphthalene imide rings and with copolyimide containing naphthalene diimide and phthalic imide structures. The obtained polymers exhibited glass transition temperatures (Tg) in the range of 227–336 °C and decomposition temperature (Td) in the range of 382–505 °C.

Research paper thumbnail of New polyamides with azo-chromophore groups

Thin Solid Films, 2004

A series of four novel polyamides with semiflexible main chains were prepared from two azo-chromo... more A series of four novel polyamides with semiflexible main chains were prepared from two azo-chromophore diamines: 2,4-diamino-4′-nitroazobenzene and 2,4-diamino-4-azo-(4′-nitroazobenzene)benzene. Polymers were obtained from diacid chlorides by the polycondensation reaction in DMA solution. The polymers were identified by infrared, 1H NMR spectroscopy and elemental analysis. The thermal properties of these polymers were investigated using differential scanning calorimetry (DSC) method and thermogravimetric