Unconventional conjugation in macromonomers and polymers

Multiple reviews have been written concerning conjugated macromonomers and polymers both as general descriptions and for specific applications. In most examples, conjugation occurs via electronic communication via continuous overlap of π orbitals, most often on carbon. These systems can be considered to offer traditional forms of conjugation. In this review, we attempt to survey macromonomers and polymers that offer conjugation involving novel forms of carbon and/or other elements but with conjugation achieved via other bonding formats, including many where the mechanism(s) whereby such behavior is observed remain unresolved. In particular, this review emphasizes silsesquioxane containing polymeric materials that offer properties found typically in conjugated polymers. However, conjugation in these polymers appears to occur via saturated siloxane bonds within monomeric units that make up a variety of polymer systems. Multiple photophysical analytical methods are used as a means to demonstrate conjugation in systems where traditional conjugation is not apparent.