Siloxane-type polymers homopolymers

Reactive Homopolymers. Types of Reactions. In the typical ringopening polymerization mentioned previously see Preparation of Siloxane-Type Polymers), reactive hydroxyl groups are automatically placed at the ends of the chains (7, 13). Substitution reactions carried out on these chain ends can then be used to convert them into other functional groups. These functionalized polymers can undergo a variety of subsequent reactions (Table III). 

A great maity SCLCPs have been synthesised because of the combination of the vast number of mesogenic core nnits available from stmctuie-property relationship evaluation of low molar mass liquid crystals and the maity different backbone (BB) types possible e.g., siloxanes, acrylates, methacrylates, ethylenes, epoxides). Additionally, as shown in Figure 5.4, homopolymers (5.4a), SC copolymers (5.4b), BB copolymers (5.4c), and SC/BB copolymers (5.4d) considerably extend the scope of known and potential liquid crystal polymers. 

First, as seen from Table II, the changes in microtacticity of PMCS-6 homopolymer up to its atactic type have no influence on the ability to form a mesophase. Quite a different situation is observed for atactic methyl-substituted POCS-4 and POCS-5. The latter polymers, like their linear analogue, polydimethyl-siloxane, are unable to form mesomorphic structures. As mentioned above, the formation of the columnar mesophase has been observed in POCS-4 with methyl side groups when its chains were enriched by trans-units (15) and in POCS-4 and -5 (14, 17) with side chains longer than methyl. Moreover, the replacement of the tetrasiloxane cycles in macromolecules of methyl-substituted POCS by the hexasiloxane ones results in a quite unexpected remarkable rise of the thermal stability of the mesophase. 

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