Anionic ring-opening polymerization silicon monomer

Almost all fimctional silicone fluids of today s industrial production are either of a cyclic nature, containing the appropriate residues, or are linear oils bearing reactive functionalities at both ends or in the chain. The chemical nature of silicone synthesis done by equilibration and condensation is prohibitive for formation of asymmetrical silicones, in contrast to organic molecules like oleic acid or even ethanol. Currently there is only one way of preparing monofunctional silicone fluids, which is through kinetic anionic ring opening polymerization of the cyclic silicone monomer hexamethyl-cyclotrisiloxane (D3). 

J.4.2.3 Heterocyclic Monomers A variety of heterocyclic monomers can be polymerized by anionic ring-opening polymerizations. The types of anionically polymerizable heterocyclic monomers include oxiranes (epoxides), thiacyclopropanes, thiacyclobutanes, lactones, lactides, lactams, anhydrides, carbonates, and silicones... 

Polymer structures are often described by using the capital letters M (mono-), D (di-), T (tri-), and Q (quadruple-) indicating the functionality of the respective monomer units. Thus linear trimethylsilyl terminated silicone fluids are characterized by M(D)xM. Linear polyorganosiloxanes can be produced either from cyclic organosiloxanes by ring-opening polymerization, which is promoted by both anionic or cationic catalysts [3, 4], or from oligomeric hydroxyterminated dimethylsiloxanes by polycondensation in the presence of acid catalysts [5, 6],... 

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