Substituted mesogens

Linear LC siloxanes have been well known since the end of the seventies [4] and an enormous variety of compounds, including networks, have been synthesized in the meantime [5]. These side-chain polymers are usually synthesized by a well-established standard procedure, that is, the coupling of co-alkenyl substituted mesogenic groups to H-siloxanes with the aid of a Pt catalyst. This concept has been extended to various geometric and chemical classes of backbone siloxanes, linear [6], cyclic [7, 8] and cage-like siloxanes [9], or siloxanes with a great variety of substituents [10]. 

Wittmann JC, Lotz B (1985) Polymer decoration the orientation of polymer folds as revealed by the crystallization of polymer vapors. J Polym Sci, Polym Phys Ed 23 205-211 Wunderlich B, Grebo wig J (1984) Thermotropic mesophases and mesophase transitions of linear, flexible macromolecules. Adv Polym Sci 60/61 1-59 Zhou QF, Li HM, Feng XD (1987) Synthesis of liquid-crystalline polyacrylates with laterally substituted mesogens. Macromolecules 20 233-234... 

Table 5.1-7 Cholesteryl (cholest-5-ene) substituted mesogens, cont. ...

The synthesis and some thermal properties of three series of block copolymers comprising both main-chain and side-chain liquid-crystalline (LC) blocks in the same macromolecular structure are described. The former block is a semiflexible LC polyester (block B), and the latter is an LC polymethacrylate (block A) containing a variously substituted mesogenic unit. The two structurally different blocks were partly phase-separated within the glassy and LC states and underwent distinct phase transitions. Significant deviations of the transition enthalpies relative to those of the corresponding homopolymers suggest the occurrence of a more or less diffuse interphase which may depend on the nature of the mesophase formed. 

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