Spiro-type ladder polymer

A spiro-type ladder polymer is produced when l,4,5,8-tetrahydro-l,4,5,8-diepoxyanthracene (23), as the bisdienophile component, is reacted with the bicyclic silaspirodiene 33 [111]. The products formed (34) in the repetitive cycloaddition (under high pressure conditions) possess number average molecular weights of up to 11000 (Dp = 13). Polymers 34 are promising candidates for... 

It thus appears that a wide variety of tetrols and cyclic diketones can be used to prepare a large variety of soluble polyspiroketals. It appears that the reaction can be made to go readily when the ketal contains either five-, six-, seven-, or eight-membered rings. Some of the polymers containing the five-, seven- and eight membered rings can, of course, be considered to be a hybrid between ladder polymers and spiro polymers. An effort will be made to see what other cyclic ketals are useful for the formation of spiro polymers and what other types of reactions besides the ketal formation will produce similar polymers. 

With 1-types it is possible to distinguish between bridge and spiro structures. Theoretically, spiro chains may be classed as single-chain polymers (see Section 2.2.3). 1-Type structures with bridging links are also known as double-strand polymers, or, because their structure is reminiscent of a ladder, they are also known as ladder polymers. Ladder polymers generally have good thermal stability, since, in contrast to linear chain polymers, the breaking of one main chain bond does not lead to a lower molar mass. 

The speeifieation of the type of structure in a polymer is shown by an italicized prefix "ladder- or "spiro- preceding poly . 

Specific rules also are applied for polymers with other regular structures such as ladder type polymers or spiro polymers [3]. For single-strand linear copolymers with irregular structures, the name is given as poly(first constitutional repeating unit/second constitutional repeating unit) , etc. Detailed explanations for polymer nomenclature can be found in various reference materials (see e.g. [4]). 

Polysiloxanes occupy a virtually imique position in the world of polymers. Many polysiloxanes comprise a partly or wholly inorganic backbone built from alternating silicon and oxygen atoms in contrast, pendent groups or side chains attached to silicon atoms are usually organic. Types discussed in this section include regular single-strand, hyperbranched, ladder, and spiro polysiloxanes. 

---