Rimantas Kublickas

Polymerization of carbazolyl-containing epoxides by activated monomer mechanism

Abstract Cationic polymerization of 3,6-dibromo-9-(2,3-epoxypropyl)carbazole and 9-(2,3-epoxypropyl)carbazole in the presence of hydroxyl-containing compounds has been studied. It has been established that, at a high enough ratio of the concentrations of a hydroxyl-containing compound and monomer, polymerization occurs by an activated monomer mechanism. Linear increase of molecular weight of polymerization products with conversion and hydroxyl functionality of ca 2 in the obtained oligomer are characteristic features of activated monomer polymerization observed in this work. Carbazolyl-containing oligomers of comparatively wide range of molecular weight and glass transition temperature were obtained. The low glass transition of the oligomers is explained by the presence of a flexible oxyalkylene fragment into the backbone of the oligomer as well as by the orderly distribution of elementary units in the main chain.

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.

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.

Polymerization of carbazolyl-containing epoxides with triphenylcarbenium salts

SummaryPolymerization of 9-(2,3-epoxypropyl) carbazole (EPC) and 1,2-epoxy-6-(9-carbazolyl)-4-oxahexane (ECOH) with triphenylcarbenium hexachloroantimonate and triphenylcarbenium tetrafluoroborate have been studied by the microcalorimetric technique. Triphenylcarbenium salts have turn out to be more efficient catalyst for the polymerization of carbazolyl-containing epoxides than Lewis acids, giving high yields at low initial concentration of the catalyst. Using comparatively restricted conditions of reaction ([triphenylcarbenium saltyda]o≥0.02 mol/l t≥50° C) transition from the conventional active chain end mechanism to the activated monomer mechanism has been observed at a sufficiently high degree of conversion of monomer.

Midus: A Traditional Lithuanian Mead

Old Lithuanian mead was made from a solution of honey and water simmered with various spices, such as thyme, lemon, cinnamon, cherries, linden blossoms, juniper berries, and hops. The solution was then strained and fermented with beer or wine yeast. These methods are still used in homemade mead making. The modern industrial Lithuanian mead technology uses three mead-making methods: basic mead, some art of metheglin, and some art of melomel, which are described in this chapter. The honey mash for production of industrial mead can be obtained from a mixture of honey and water (a ratio of 1:1 to 1:4) or a mixture of honey, fruit juice, and water (a ratio of 1:1:3). Mead can be amber to a shade of brown. Its taste and aroma can be characterized as honey, with a sour and sweet flavor, and hops aroma.