Juozas V. Gražulevičius

Hole-transporting molecular glasses based on carbazole and diphenylamine moieties

Abstract Various molecular designs based on carbazole and diphenylamine moieties are found to constitute novel hole transporting amorphous molecular materials, as characterized by differential scanning calorimetry and time of flight method. Hole drift mobility of synthesized materials were in the range 10 −4 –10 −6 cm 2 V −1 s −1 at an applied field of 3.6×10 5 V cm −1 .

Study on the initiation step of 2-(9-carbazolyl)ethyl glycidyl ether polymerization by K−, K+ (15-crown-5)2

Abstract Several reactions occur during the initiation of 2-(9-carbazolyl)ethyl glycidyl ether polymerization by K−, K+ (15-crown-5)2. At first the oxirane ring is opened mainly in the β-position. An organometallic intermediate obtained cleaved then the linear ether bond in the substituent and the cyclic one in crown ether. Various potassium alkoxides are finally formed. They are the real initiators of the polymerization. 9-Vinylcarbazole being another reaction product is inactive in this process.

Polymerization of 3,6-Dibromo-9-(2,3-Epoxypropyl)Carbazole with Lewis Acids

Abstract The kinetics of polymerization of 3,6-dibromo-9-(2,3-epoxypro-pyl) carbazole with stannic chloride and boron trifluoride etherate were studied by a microcalorimetric technique. Complex kinetics of the polymerization rate were observed. A spontaneous increase of the reaction rate was recorded after it decreased and after polymerization for some time at the minimal rate. This effect is explained by a change in the mechanism of polymerization. At the high enough degree of conversion, transition from an active chain end mechanism to an activated monomer mechanism takes place.

Synthesis and cationic polymerization of 5-(2,3-epoxypropyl)amino-2-phenyl-1,2,3-benzotriazole

Abstract Synthesis and cationic polymerization of the new monomer 5-(2,3-epoxypropyl)amino-2-phenyl-1,2,3-benzotriazole (EAPB) is reported. The monomer was prepared either in the reaction of 5-amino-2-phenyl-1,2,3-benzotriazole with 1-chloro-2,3-epoxypropane or by the treatment of 5-(3-chloro-2-hydroxypropyl)amino-2-phenyl-1,2,3-benzotriazole with sodium hydroxide. Polymerization of EAPB with boron trifluoride diethyl etherate yielded the oligomers with the average degree of polymerization of 4–5. The limit conversion of the monomer did not exceed 53%. The introduction of 1,2-ethane diol into the reaction mixture led to the higher yield of the oligomer. Investigation of polymerization of EAPB by GPC and microcalorimetry as well as analysis of the resulting oligomers by IR spectrometry has shown that, in the presence of 1,2-ethanediol, the reaction proceeds by an activated monomer mechanism, whereas in the absence of the diol, it proceeds by the conventional active chain end mechanism.

Cationic photopolymerization of carbazolyl- and phenothiazinyl-containing thiiranes

Abstract Photopolymerizations of ((9-carabzolyl)methyl)thiirane (CMT) and ((10-phenothiazinyl)methyl)thiirane (PMT) initiated with di-( tert -butylphenyl)iodonium tetrafluoroborate (BPIT), diphenyliodonium tetrafluoroborate (DPIT), cyclopropyldiphenylsulfonium tetrafluoroborate (CPS) and (η 5 -2,4-cyclopentadien-1-yl) [1,2,3,4,5,6-η)-(1-methylethyl)benzene]-iron (+)-hexafluorophosphate(-1) (Irgacure 261) are reported. The influence of temperature and photoinitiator concentration on the rate of polymerization and conversion limit is discussed. The values of initiator exponent and activation energy for the photopolymerizations of CMT and PMT initiated with BPIT in 1,2-dichloroethane solution have been established.

Electron-transfer processes in the reaction of K−, K+(15-crown-5)2 with carbazole: unexpected formation of metallic potassium

Abstract Transfer of one electron from K − to the aromatic ring occurs in the reaction of K − , K + (15-crown-5) 2 with carbazole giving K° and a radical anion. The latter rapidly decomposes with the liberation of hydrogen and formation of carbazylpotassium. It can also undergo an intramolecular proton-exchange reaction followed by a transfer of the second electron from the part of K° product. That leads to a dianion which then reacts with another carbazole molecule. Finally, carbazylpotassium and 1,4-dihydrocarbazylpotassium are formed.

Cationic Photopolymerization of 1, 2‐Epoxy‐6‐(9‐carbazolyl)‐4‐oxahexane Initiated by Sulfonium Salt and Iron Arene Complex

The photopolymerization of 1,2-epoxy-6-(9-carbazolyl)- 4-oxahexane (ECOH) initiated with dual function sulfonium salt bis [4(diphenylsulfonio)-phenyl] sulfide-bishexafluoroantimonate (Cyracure ® UVI 6974) and ( η5-2,4-cyclopentadien- 1-yl) [(1,2,3,4,5,6-η)-(1-methylethyl)benzene]-iron (+)-hexafluorophosphate (—1) (Irgacure ® 261) has been studied. Higher rate constant values and degrees of polymerization are established for the ECOH photopolymerization initiated with Cyracure ® compared with those obtained using Irgacure ® . The influence of temperature on the rate of ECOH photopolymerization, molecular weight and conversion limit is discussed. The activation energy for the photopolymerization of ECOH with the sulfonium salt has been established.

Photopolymerization of carbazolyloxiranes with sulphonium and tropylium salts

Abstract The photopolymerization of 1-allyloxa-3-(carbazol-9-yl)-2-propanol glycidyl ether (ACPGE) and 1-(carbazol-9-yl)-4-oxa-2-pentanol glycidyl ether (COPGE) with cyclopropyldiphenylsulphonium tetrafluoroborate and tropylium hexafluorophosphate is reported. Oligomers with a degree of polymerization of 9–19 were obtained in the photopolymerization of ACPGE with these salts. The photopolymerization of COPGE yielded oligomers with a degree of polymerization of 4–5. The behaviour of tropylium and sulphonium salts is discussed. Tropylium hexafluorophosphate initiates both the photopolymerization of carbazolyloxiranes and the cationic polymerization of unsaturated monomers. Cyclopropyldiphenylsulphonium tetrafluoroborate acts exclusively as a photoinitiator.

Polymerization of 3,6-dibromo-9-(2,3-epoxypropyl)carbazole with triphenylcarbenium salts

Abstract Cationic polymerization of 3,6-dibromo-9-(2,3-epoxypropyl)carbazole with triphenylcarbenium salts (triphenylcarbenium hexachloroantimonate, triphenylcarbenium tetrafluoroborate and triphenylcarbenium pentachlorostannate ) has been studied by a microcalorimetric technique. Acceleration of polymerization after reaching about 70% conversion of the monomer has been observed. The onset of acceleration coincides with the beginning of the linear increase of M n with conversion and with the moment when the concentration of OH-groups in the reaction mixture becomes constant. The observed phenomena are explained by the change of polymerization mechanism from the conventional active chain-end mechanism to the activated monomer mechanism. After complete conversion of the monomer, polymerization mixtures can be used for the casting of electrophotographic layers in which the residual catalyst acts as sensitizer. Such layers exhibit high photoconductivity in the visible region.

Heats of polymerization of carbazolyl-substituted epoxides

SummaryHeats of polymerization of three carbazolyl-containing epoxides 9-(2,3-epoxypropyl)carbazole, 1,2-epoxy-6-(9-carbazolyl)-4-oxahexane and 3,6-dibromo-9-(2,3-epoxypropyl) carbazole have been determined on the differential microcalorimeter DAK 1-1A (USSR). The influence of the structure of monomers upon the values of polymerization heat is discussed.