Liquid crystalline polymers by living polymerization

A comprehensive review about the engineering and preparation of side-chain liquid-crystalline polymers by living polymerization methods including ROMP has been given recently. Consequently, only the more recent contributions shall be covered briefly. One convenient approach for the preparation of side-chain liquid-crystalline materials entails the ROMP of norbornenes carrying mesogenic side groups in the... 

Molecular Engineering of Side Chain Liquid Crystalline Polymers by Living Polymerizations ... 

This article is reprinted with permission from C. Pugh, A. Kiste, Progress in Polymer Science, Vol. 22 Molecular Engineering of Side-Chain Liquid Crystalline Polymers by Living Polymerization, (1997), Elsevier Science Ltd., Oxford, England. 

MOLECULAR ENGINEERING OF LIQUID CRYSTALLINE POLYMERS BY LIVING POLYMERIZATION... 

Peng H, Chen Y, Chen L, He X, Li F (2010) Luminescent mesogen jacketed poly(l-alkyne) bearing lateral terphenyl with hexyloxy tail. J Polym Sci Part A Polym Chem 48 5679-5692 Percec V, Tomazos D (1992) Molecular engineering of side-chain liquid-crystalline polymers by living cationic polymerization. Adv Mater 4 548-561... 

Living polymerizations in which initiation is fast and quantitative and which have irreversible growth offer several advantages over conventional polymerizations. In addition to the ability to obtain polymers with controlled molecular weights and narrow molecular weight distributions, it is also possible to control the polymer architecture and chain end functionality. For example, diblock and triblock copolymers containing liquid crystalline blocks have been prepared by living polymerizations. 

Additional well-defined side-chain liquid crystalline polymers should be synthesized by controlled polymerizations of mesogen-ic acrylates (anionic or free radical polymerizations), styrenes (anionic, cationic or free radical), vinyl pyridines (anionic), various heterocyclic monomers (anionic, cationic and metalloporphyrin-initiated), cyclobutenes (ROMP), and 7-oxanorbornenes and 7-oxanorbornadienes (ROMP). Ideally, the kinetics of these living polymerizations will be determined by measuring the individual rate constants for termination and... 

The homopolymer, prepared by polymerization in liquid ammonia with sodium initiator at-77 °C, is insoluble in acetone, but it is soluble in dimethylformamide. When it is formed with lithium in liquid ammonia, at -75 °C, the molecular weight of the product increases with monomer concentration and decreases with initiator concentration. If, however, potassium initiates the reaction rather than lithium, the molecular weight is independent of the monomer concentration. " " Polymethaciylonitrile prepared with n-butyllithium in toluene or in dioxane is crystalline and insoluble in solvents like acetone. When polymerized in petroleum ether with /i-butyllithium, methacrylonitrile forms a living polymer. Highly crystalline polymethacrylonitrile can also be prepared with beryllium and magnesium alkyls in toluene over a wide range of temperatures. 

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