Abstract: A two part curable composition comprising organosiloxane polymer; water; an organosilane such as hexamethyldisilazane (HMDS) or vinyltrimethoxysilane; crosslinker; adhesion promoter and catalyst; and optionally comprising plasticizer; colorant and filler. The first part can comprise organosiloxane polymer and water. The second part can comprise crosslinker; adhesion promoter and catalyst. Either or both parts can optionally further comprise an organosilane such as hexamethyldisilazane (HMDS) or vinyltrimethoxysilane; plasticizer; colorant and filler. The mixed parts have a low viscosity allowing injection under low pressure. Cured reaction products of the two part curable organosiloxane composition has good adhesion to metallic sealing surfaces and good resistance engine oil and other automotive fluids. Cured reaction products of the two part curable organosiloxane composition can surprisingly retain physical properties after long-term exposure to temperatures between 200° C. and 250° C.

Abstract: Disclosed is a method for formation of block copolymers using a Single Electron Transfer Living Radical Polymerization (SET-LRP) process. The process can be used to form di and tri-block copolymers from vinyl monomers. In one embodiment the SET-LRP process comprises initially forming a macroinitiator using SET-LRP to form a first block of a di or tri-block copolymer and then using SET-LRP to form additional blocks of the copolymer. The produced block copolymers have very narrow polydispersity indexes and controlled molecular weights. The process permits incorporation of photoinitiators in any of the block formation reactions. The method also includes purification processes that result in a block copolymer having very low color making it useful in a variety of applications. In one application block copolymers prepared according to the present process can be used in hot-melt adhesives.