Organosiloxanes (Silicones), Polyorganosiloxane Block Copolymers

Membranes based on polyorganosiloxane block copolymers (POBCs) are characterized by high permeability for various gases and good mechanical strength. Gas permeability parameters, separation selectivity, and physicomechanical properties can be controlled by changes in the molecular structures of both organosilicon and organic fragments or physicochemical interchain interactions in copolymers. The main synthetic task encountered in the design of efficient gas separation membrane materials based on POBC involves obtaining a combination of organosiloxane and organic components that could ensure the high permeability of siloxanes along with the good selectivity typical of some organic polymers. This chapter highlights the general aspects of synthesis, manufacturing procedure, properties, and application of organosiloxanes. It describes the syntheses of some particular representatives of carbofunctional monomers and oligomers that exhibit the most promise for the manufacture of membrane materials. Organosilicon compounds containing hydroxyl and hydroxyphenyl groups in an organic substituent at the silicon atom are of interest as initial monomers and oligomers for preparing various polyester–polyurethanesiloxane copolymers.