Siloxane-type polymers ladder polymer

These include inorganic and quasi-inorganic polymers, double-strand (ladder) polymers, siloxanes and silicones, and oligomers and telomers. A comprehensive review of structure-based and source-based representations for these types of polymers has been published (40). 

In this regard, crystallization is very important in the case of elastomers, since crystallites can act as reinforcing agents, particularly if they are strain induced. For this reason, it is of interest to make siloxane-type backbones with increased stiffness, in an attempt to increase the Tm of the polymer. Examples of ways to make a polymer more rigid is to combine two chains into a ladder structure, insert rigid units such as p-phenylene groups into the chain backbone, or add bulky side groups to the backbone. 

Upon electron impact of different energy, oligoforganylsilsesquioxanes) may polymerize with either abstraction of hydrocarbon radicals (C—C bond rupture) and formation of ladder-type molecules cross-linked by alkylene bridges or cleavage of siloxane bonds and formation of polymers of irregular structure... 

However the realization of cis-isotactic structure is associated with several steric hindrances and characterized by a short length of the molecules. During the tetrole polycondensation without initiator of the basis type, which allows the obtaining of the polymer without break of siloxane bond in the organocyclosiloxane, the conditions of synthesis ensures the perfect cyclolinear ladder structure and the macromolecules with the Kuhn segment with length about 50 A are formatted. 

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