Controlled free radical agent for nanocomposite synthesis

摘要

This invention relates to a process for producing a free radical control agent of the structural formula: wherein Z is selected from the group consisting of wherein R¹ is an alkyl group of 1 to 4 carbon atoms, cyclohexyl or phenyl; wherein R² is an alkoxy group of 1 to 8 carbon atoms or a cycloalkoxy group of 5 to 8 carbon atoms; wherein Alk is a divalent hydrocarbon of 1 to 18 carbon atoms; and wherein Y represents a functional group that is capable of activating a vinylic carbon toward free radical addition; said process comprising the steps of (1) reacting a mercaptosilane of the structural formula: Z-Alk-SH with carbon disulfide in the presence of a phase transfer catalyst and an alkali metal hydroxide to produce a trithiocarbonate sa and (2) reacting the trithiocarbonate salt with a halogen containing compound of the structural formula X-Y to produce the free radical control agent, wherein X represents a halogen atom. Such free radical control agents are capable of covalently bonding to silica/silicate surfaces and are of particular benefit in producing rubbery compounds that will be loaded with silica fillers, such as tire tread rubbers.