Analysis And Preparation Of Polysiloxane Containing Chloropropyl

γ -chloropropylmethyldimethoxysilane(MCPS) have chloropropy groups and double methoxy groups, so it can be used to produce some coupling agents or copolymerize with octamethylcyclotetrasiloxane(D4) to make the new siloxane copolymer which contains the chloropropy groups at side chains. The new copolymer and its devirant are comprehensively used in many fields, like Rubber Industry, Plastic Industry, Print or Industry of fine chemicals,etc.Taking potassium hydroxide as catalyst, we found the 3-chloropropylsilyl groups are attacked by potassium hydroxide or silanolate active propagation centers during the copolymerization of γ -chloropropylmethyldimethoxysilane with octamethylcyclotetrasiloxane. These attacking reactions produce a lot of free chlorine ions. The mechanism of the reactions is deduced and proved by the kinetic parameters which are obtained from experimental results. There are three competitive reactions in the copolymerization system, and the dechlorination reaction is the dominant one.Taking acid clay as catalyst, we suggest a new mechanism which about D4/MCPS copolymerization reaction. At the first step, the ring-opening reactions make D4 transform to silanol group. Then the silanol group reacts with SiOCH₃ group, which produce the SiOSi group. We find that the silanol group is very active, if the reaction system has many MCPS, the silanol group's activity will be different with which often happens at a common acid catalyst polymerization system. It will not combine with catalyst to get the active center which can catalyse the polymerization reaction. It prefer to react with SiOCH₃ group to produce the SiOSi group, H₂O or CH3OH; the active centers will be destroyed at this reaction, so we only can get some low molecular weight polymers. Meanwhile, the chloropropyl groups will end the polymer chains but not at the side chains.Taking acid clay as catalyst, we study the copolymerization between MCPS and other siloxanes. At last we get a appropriate reaction conditions to produce the polymer.