Overview of Siloxane Polymers

This review provides coverage of a variety of polysiloxane homopolymers and copolymers, and some related materials. Specific systems include (i) linear siloxane polymers [-SiRR'O-] (with various alkyl and aryl R and R' side groups), (ii) sesquisiloxane polymers possibly having a ladder structure, (iii) siloxane-silarylene polymers [-Si(CH3)2OSi(CH3)2(C6H4)m-] (where the phenylenes are either meta or para), (iv) silalkylene polymers [-Si(CH3)2(CH2)m-]. (v) polysiloxanes of exhanced crystallizability through modifications of chemical and stereochemical structures, (vi) elastomers from water-based emulsions, and (vii) random and block copolymers, and blends of some of the above. Topics of particular importance are preparative techniques, end-linking reactions, and the characterization of the resulting polymers in terms of their structures, flexibilities, transition temperatures, permeabilities, and surface and interfacial properties. Applications of these materials include their uses as high-performance fluids, elastomers, coatings, surface modifiers, separation membranes, soft contact lens, body implants, and controlled-release systems. Also of interest is the use of sol-gel hydrolysis-condensation techniques to convert organosilanes to novel reinforcing fillers within elastomers, and to ceramics modified by the presence of elastomeric domains for the improvement of impact strengths.