SYNTHESIS OF NEW SILOXANE URETHANE BLOCK-COPOLYMERS AND THEIR PROPERTIES

Siloxane urethane block copolymers were prepared with siloxanes as the soft segment. Films were cast from a variety of solvents. Solvent has an effect on the segregation of soft and hard segments. Surface studi es, including ESCA, EDS, and FT-IR, show well segregated block copolym ers with enhanced siloxane on the surface. DSC studies show a low mp ( -44-degrees-C) for the soft segment and a T(g) for the hard segment ab ove room temperature. These materials show higher thermal stability co mpared to polyether urethane block copolymers. These copolymers also s how relatively good resistance to exposure to oxygen plasma and show i mproved flame retardancy compared to nonsiliconated, polyether polyure thane block copolymers. (C) 1994 John Wiley & Sons, Inc.