Eight Methyl Ring Siloxane Modified Acrylic Emulsion

The goals for this work are to get a better understanding on the emulsion polymerization of polysiloxane-modified-polyacrylate, which was used as an important composite in civic buildings' outside-wall-dope. Poly(siloxane/acrylate) was synthesized by emulsion polymerization by using octamethyltetracyclosiloxane (D4), 3-(trimethoxylsilyl)propyl methacrylate (MATS)- BA. MMA and AA as raw materials, potassium peroxydisulfate , OS/AP065 as initiator and emulsifiers respectively. This study was divided into two parts: the first part is about the mechanism of anionic emulsion polymerization of D4 and the optimum conditions were got by experiments. The second part is synthesizing poly(siloxane/acrylate) latex with MATS used as coupling agent and polysiloxane which has been got in the first part. Optimum lab conditions were got by experiments. And also factors that affect the performance of latex mostly were studied.Factors including temperature, catalysts systems and its dosage which affect reaction's velocity, molecular weight and the latex's stability are studied in anionic polymerization of D4. Under the optimum conditions ?temperature is 80癈, the dosage of DBSA is 3%-5% ,reaction time is 6h, Molecular weight can reach 60 thousand to 80 thousand. Reaction progression and AEa were calculated. And latex particles formation and its transformation during reaction process were studied. It was found that the existence of large particles called "transition-layer-particles" was the main-cause of the instability of the latex, which led to the appearance of "floating oil".In emulsion polymerization of poly(siloxane/acrylate), factors including temperature, catalysts systems and its dosage, polysiloxane which affect latex's particles size & distribution and Ca2+-stability arestudied. When polysiloxane's amount is 10% of acrylate, temperature was controlled between the OS/AP065 was added gradually whose adding amount is 3% of system, latex with good performance can be synthesized. Then membrane's properties of polymer were studied via different dosage and adding ways of MATS. While the MATS' amount is 5% of polysiloxane, its hydrophile angle is bigger than 90?It shows that its anti-water property is very good. The role of MATS in this reaction was studied by TG. DTG. DTA. IR and SEM analysis: In this system MATS acted as transition agent reacted with both polysiloxane and acrylate.