Ministry of science
and Higher Education of Russia
The state-of-the-art in the field of molecular design, synthesis, and characterization of the structure and physicochemical properties of liquid-crystalline (LC) dendrimers is reviewed. The first classification of LC dendrimers taking into account both the arrangement of their functional elements (mesogens) in macromolecules and the mechanism of mesophase formation (mesogen interaction versus microphase separation) is pre- sented. The LC dendrimers with terminal mesogens are also classified with respect to the nature of their dendritic matrices into siloxane, polyurethane, poly(propylene imine), poly(amidoamine), polyester, and carbosilane types. The effects of various structural factors (spacer length, mesogen chemistry, and the nature of dendritic matrix) and the LC dendrimer generation number on the phase behavior and physicochemical properties of LC dendrimers are considered. General laws of the mesophase formation in dendritic macromolecules are formulated.
Authors: Ponomarenko S.A., Boiko N.I., Shibaev V.P.,
The present review provides a general idea concerning the history and state of the art in the synthesis of alternating copolymers of linear and cyclic olefins, various vinyl monomers, linear and cyclic dienes, allenes and functional derivatives of the above monomers with carbon monooxide under the action of primarily bidentatePAP, PAN, and NAN palladium complexes. The specific features of the synthesis of the above copolymers are reviewed, the effects of various conditions on the copolymerization rate, molecular mass, and structure of the as-formed copolymers are studied, and the mechanism of the copolymerization and nature of the catalytically active species are considered. The properties of aliphatic poly(ketones) based on ternary alternat- ing ethylene-carbon monooxide-propylene copolymers are described; the above compounds are shown to present a certain interest as engineering composite materials and matrices for composites.
Authors: Belov G.P.,
The data that were reported during the last 15 years on the nonuniformity of catalytic systems used in the polymerization of unsaturated compounds are collected and analyzed. The multiplicity of heterogeneous, microheterogeneous, and homogeneous catalysts is exemplified. The methods for obtaining information about the kinetic and stereospecific nonuniformity distribution of active sites in catalytic systems are discussed. It is concluded that the multiplicity of catalytic systems is typical for the majority of ionic and ion-coordination po lymerization processes.
Authors: Monakov Yu. B., Sigaeva N.N.,
Physicochemical principles of pseudoliving radical polymerization and copolymerization in the mode of reversible inhibition by nitroxides, stable radicals, cobalt(ll) complexes, and other compounds; the specific features of the kinetics and mechanism of elementary reaction steps; and conditions for the formation of a narrow molecular-mass distribution of polymers are reviewed. The possibility of using reversible inhibition reactions for macromolecular design is discussed.
Authors: Zaremskii M. Yu., Golubev V.B.,