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New azomethine-phthalic (AzPhDIs) and azomethine-naphthalene (AzNDIs) diimides were synthesized in condensation reaction of diamines containing phthalic or naphthalene diimide core and two aldehydes: 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde and 4-octadecyloxybenzaldehyde. The phase behavior of azomethine-diimides was examined by differential scanning calorymetry (DSC) and polarized optical microscopy (POM). AzPhDIs exhibited liquid crystalline properties in wide temperature range, whereas AzNDIs were not liquid crystalline. Thermal stability was investigated by thermogravimetric analysis (TGA). Azomethine-diimides exhibited high decomposition temperatures in the range between 360 and 401 °C. Optical properties were studied by UV–vis and photoluminescence (PL) measurements. Azomethine-diimides emitted blue light in NMP solution and blends with PMMA. The investigated compounds were electrochemically active and underwent reversible reduction and irreversible oxidation processes as evidenced by cyclic voltammetry (CV). Azomethine-diimides exhibited LUMO and HOMO levels in the range of −3.87 to −4.2 eV and −5.56 to−6.02 eV, respectively.

Chemical modification based on incorporation of flame retardants (FR) into the polymer backbone was used in order to reduce polystyrene flammability. Boronated styrenes such as 4-vinylphenylboronic acid (StB(OH)2) and 6-methyl-2-(4-vinylphenyl)-1,3,6,2-dioxazaborocane-4,8-dione (StBcyclo) were applied as reactive FR. Homo- and copolymers of boronated styrenes and styrene (St) were synthesized with different feed ratios using free radical polymerization. It yielded in series of (co)polymers with various amounts of StB(OH)2 and StBcyclo (5–20% mol/mol of St). Copolymer compositions were determined by 1H NMR. The relative reactivity ratios of system St-StBcyclo were determined by applying the Jaacks method. Glass transition temperature and thermal stability of obtained (co)polymers were determined from DSC and TGA analysis, respectively. The pyrolysis combustion flow calorimeter was applied as a tool for assessing the flammability of the synthesized (co)polymers. Copyright © 2014 John Wiley & Sons, Ltd.

The azines being condensation products of benzophenone hydrazone with triphenylamine substituted with different numbers of aldehyde groups and also with terephthaldicarboxaldehyde were prepared. Their spectral, thermal and electronic properties that is, orbital energies and resulting energy gap calculated theoretically by density functional theory (DFT) and estimated by electrochemical measurements were explored. The prepared hydrazine derivatives exhibited glass-forming properties with glass-transition temperatures in the range of 10–98 C and high thermal stability with decomposition temperatures placed between 231 and 337 C. The photoluminescence (PL) studies showed that all investigated compounds both in solid state as blends with PMMA and in NMP solution emitted blue light, however, with different intensity. Relative PL intensity of azines was investigated in NMP in relation to rhodamine-B used as a standard. Moreover, the stability of azines during doping with acid and ferric chloride was spectroscopically demonstrated via repeated doping/dedoping in solution and in film. All compounds are electrochemically active. Depend on chemical structure of azines they undergo reversible or irreversible electrochemical oxidation and reduction processes. The LUMO levels were found in the range from � 2.66 to � 3.0 eV. They exhibited energy band gap (Eg) estimated electrochemically from 2.57 to 3.22 eV.

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, 1 H 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/m 2 .

Azobenzene-containing poly(amic acid)s and resulting polyimides were synthesized. Polymers differed in the polymer backbone structure and the position at which the azobenzene group was attached to the polymer chain. Polymers were characterized and evaluated using Fourier transform infrared, 1H NMR and UV-visible spectroscopies, X-ray diffraction, differential scanning calorimetry (DSC) and thermogravimetric analysis. Polyimides revealed glass transition temperatures in the range 160–265 °C, and thermal stability with decomposition temperatures in the range 336–444 °C. The thermal imidization kinetics of poly(amic acid)s was investigated by means of DSC. Kinetic parameters, such as the activation energy (E) and the frequency factor, were estimated using the Ozawa and Kissinger models. The values of E, determined using both methods, were in the range 142.52–200.92 kJ mol−1. The photoinduced optical anisotropy (POA) was studied in the obtained azopolymers using a holographic grating recording technique. Surface relief gratings, which appeared after light exposure, were observed using atomic force microscopy. For the first time to the best of our knowledge, photoinduced anisotropy in poly(amic acid)s was studied and compared with POA in their polyimide analogues. © 2014 Society of Chemical Industry

Chemical modification based on incorporation of flame retardants into polymer backbones was used in order to reduce flammability of polystyrene (PSt). The halogeno-substituted styrenes: 4-chlorostyrene (ClSt), 4-bromostyrene (BrSt) and 2,3,4,5,6-pentafluorostyrene (5FSt) were applied as reactive flame retardants. Homo- and copolymers of these halogeno-substituted styrenes and styrene (St) were synthesized with various feed ratios using free radical bulk polymerization with azobisisobutyronitrile as a initiator. This yielded series of (co)polymers with various amounts of included ClSt, BrSt and 5FSt (5–50 mol% of modified St). Copolymer compositions were determined using 1H NMR spectroscopy. The relative reactivity ratios of the used comonomers were determined by applying conventional linearization methods. The Jaacks (J) method was used for systems including BrSt and ClSt monomers whereas the Fineman–Ross method was additionally used to confirm the values of reactivity ratios of St–5FSt. The reactivity ratios of comonomer pairs obtained from J plots were 0.75 and 0.38 (St–ClSt), 1.65 and 0.46 (St–BrSt), 0.44 and 0.42 (St–5FSt). Glass transition temperature and thermal stability of obtained (co)polymers were determined using differential scanning calorimetry and thermogravimetric analysis (TGA), respectively. The thermal degradation kinetic of PSt, PClSt, PBrSt and P5FSt was studied applying TGA. Kinetic parameters such as thermal decomposition activation energy (E) and frequency factor (A) were estimated using Ozawa and Kissinger models. The resulting activation energies estimated using these two methods were quite close. The values of activation energy (kJ mol−1) increased in the following order: PClSt (E(O) = 216.1) < PSt (E(O) = 219.9) < PBrSt (E(O) = 224.7) < P5FSt (E(O) = 330.9). A pyrolysis combustion flow calorimeter was applied as a tool for assessing the flammability of the synthesized (co)polymers. © 2014 Society of Chemical Industry

The paper describes the synthesis and characterization of aromatic polyimides with azopyridine derivatives covalently attached as a side-chain and their supramolecular analoges based on the hydrogen bonds. Moreover, azopolymers differ in the chemical structure of the polymer backbone and the content of the chromophore. Azo-functionalized polymers were obtained by a two-step synthetic approach. This includes the preparation of a precursor with pendant hydroxyl groups followed by the covalent attachment of the chromophore, that is, 4-[4-(6-hydroxyhexyloxy)phenylazo]pyridine to the polyimide backbone. The degree of functionalization of the polymers was estimated by the UV–Vis spectroscopy. Supramolecular films were built on the basis of the hydrogen bonds between the hydroxyl groups of the polymer and azopyridine derivatives, that is, 4-(4-hydroxyphenylazo)pyridine and 4-[4-(6-hydroxyhexyloxy)phenylazo]pyridine. The polymers were characterized and evaluated by FTIR, 1H NMR, X-ray, UV–Vis, DSC and TGA methods. The synthesized precursor polymers revealed the glass transition temperature (Tg) in the range of 254–366 °C, whereas azopolymers and supramolecular systems exhibited lower Tg within the ranges 129–153 °C and 53–171 °C, respectively. The polymers were easily soluble in common organic solvents enabling to obtain films of a good optical quality. The light-induced optical anisotropy was studied with the help of the holographic recording. The polymer films were investigated by an atomic force microscopy before and after the diffraction grating recording in order to confirm the formation of surface relief gratings. To the best of our knowledge, for the first time the photoinduced anisotropy in polyimides functionalized with azopyridine units has been compared with their supramolecular systems analoges.

Homo- and copolymers of 4-fluorostyrene (FSt) and styrene (St) were synthesized with different feed ratios using free radical bulk polymerization with azobisisobutyronitrile (AIBN) as initiator. It yielded series of (co)polymers with various amounts of included FSt, P(St-co-FSt) (5–50 mol%) and PFSt. The effect of the initiator concentration on the molecular weights of the homopolymers, that is, PSt and PFSt was investigated. Copolymer compositions were determined by nuclear magnetic resonance spectroscopy. The relative reactivity ratios of both comonomers were determined by applying the conventional linearization methods of Jaacks (J), Finemann–Ross (F–R), inverted Finemann–Ross (IF–R), and Kelen-Tudos (K–T). The reactivity ratios values of St and FSt obtained from J plot are 1.06 and 0.84, F–R plot are 1.18 and 1.06, IF–R 1.01 and 0.86, and K–T plot 1.04 and 0.88, respectively. Thermal properties of prepared (co)polymers, that is, glass transition temperature (Tg) and thermal stability, were determined from differential scanning calorimetry and thermogravimetrical measurements. The lack of significant influence of FSt comonomer content on Tg of (co)polymers was observed. Additionally, the thermal degradation kinetics of obtained PSt and PFSt was studied by thermogravimetric analysis. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa model [E(O) and A(O), respectively] and Kissinger model [E(K) and A(K), respectively]. The activation energy and the frequency factor of PFSt (253 kJ/mol) were higher than PSt (236 kJ/mol). The resulting activation energies estimated using the two methods were quite close. POLYM. ENG. SCI., 54:1170–1181, 2014. © 2013 Society of Plastics Engineers

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.

Chemical modification based on incorporation of flame retardants (FR) into the polymer backbone was used in order to reduce polystyrene flammability. 3-(trifluoromethyl)styrene (StCF3) and 3,5-bis(trifluoromethyl)styrene (St(CF3)2) were applied as reactive FR. Copolymers were synthesized with different feed ratios and it gave series of copolymers with various amounts of StCF3 and St(CF3)2 (5–50% mol/mol of St). Glass transition temperature (Tg) and thermal stability of obtained (co)polymers were determined from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. Kinetic parameters such as the thermal decomposition activation energy (E) and frequency factor (A) were estimated by Ozawa and Kissinger models. Pyrolysis combustion flow calorimeter (PCFC) was applied as a tool for assessing the flammability of the synthesized (co)polymers. Relative reactivity ratios were determined by applying the conventional linearization Jaacks method (rSt = 1.34, rStCF3 = 0.54), (rSt = 0.47, rSt(CF3)2 = 0.13). The results suggest that incorporation of fluorinated styrenes into PSt enchance flame retardance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42839.

New symmetrical arylene bisimide derivatives formed by using electron-donating–electron-accepting systems were synthesized. They consist of a phthalic diimide or naphthalenediimide core and imine linkages and are end-capped with thiophene, bithiophene, and (ethylenedioxy)thiophene units. Moreover, polymers were obtained from a new diamine, N,N′-bis(5-aminonaphthalenyl)naphthalene-1,4,5,8-dicarboximide and 2,5-thiophenedicarboxaldehyde or 2,2′-bithiophene-5,5′-dicarboxaldehyde. The prepared azomethine diimides exhibited glass-forming properties. The obtained compounds emitted blue light with the emission maximum at 470 nm. The value of the absorption coefficient was determined as a function of the photon energy using spectroscopic ellipsometry. All compounds are electrochemically active and undergo reversible electrochemical reduction and irreversible oxidation processes as was found in cyclic voltammetry and differential pulse voltammetry (DPV) studies. They exhibited a low electrochemically (DPV) calculated energy band gap (Eg) from 1.14 to 1.70 eV. The highest occupied molecular orbital and lowest unoccupied molecular orbital levels and Eg were additionally calculated theoretically by density functional theory at the B3LYP/6-31G(d,p) level. The photovoltaic properties of two model compounds as the active layer in organic solar cells in the configuration indium tin oxide/poly(3,4-(ethylenedioxy)thiophene):poly(styrenesulfonate)/active layer/Al under an illumination of 1.3 mW/cm2 were studied. The device comprising poly(3-hexylthiophene) with the compound end-capped with bithiophene rings showed the highest value of Voc (above 1 V). The conversion efficiency of the fabricated solar cell was in the range of 0.69–0.90%.