Preparation Of Vinyl-polysiloxane Macromolecules By Emulsion Polymerization And Their Properties

Silicone polymers are a class of hybrid organic/inorganic dual characteristics polymers, that show many excellent physical and chemical properties such as high and low temperature resistance, weatherablity, water repellency, physiological inert and so on. They have been widespread applied in different industrial area. Furthermore, silicone emulsions are used in many applications including finishing agent for textile, polishing agent for transportation and furniture, antifoaming agent, additives in cosmetic, delivery for pharmaceuticals, etc. In the past20years, the linear poly(dimethylsiloxane)s (PDMSs) were prepared by the ring-opening emulsion polymerization of octamethylcyclotetrasiloxane(D4) that there were many reports. However, the emulsion copolymerization of D4and vinyl-silicone monomers was few reported. Especially, the research of vinyl-polysiloxane(Vi-PDMS) macromonomers by emulsion copolymerization using the base catalyzed ring-opening of cyclosiloxanes was rarely reported. In this paper, the Vi-PDMS macromonomers emulsions were prepared by emulsion copolymerization using potassium hydroxide(KOH) as the catalyst, cetyltrimethyl-ammonium bromide(CTAB) and octylphenol polyoxyethylene(10) ether(OP-10) as the compound emulsifying agents, tetramethyltetravinylcyclotetrasiloxane(D4Vi), y-methacryloxyl-propyltrimethoxylsilane(MPS) and D4as the raw materials.In the study of D4/D4Vi emulsion copolymerization, the effects of amount and ratio of the compound emulsifying agents, KOH concentration, amount and ratio of cyclosiloxanes, reaction temperature on emulsion properties such as latex particles size and distribution, ξ potential of latex particles, molar mass of copolymers, emulsion stability were investigated. The results showed that the best condition of copolymerization as follows:the amount of the compound emulsifying agents was5.72%of the emulsion system, the mass ratio of CTAB and OP-10was1:6, the amount of KOH was0.191%of the emulsion system, the amount of cyclosiloxanes was lower than30%of the emulsion system, the mass ratio of D4and D4Vi was9:1, reaction temperature was80℃, reaction time was8.5h. The apparent copolymerization kinetics and activation energy were found to be Rp=k[E]0.18[KOH]0.59[M]0.75and, Ea=52.77kJ/mol respectively. FTIR proved that the copolymerization occurred in D4and D4Vi. The morphology of latex particles were characterized by TEM. The thermal decomposition temperature of Vi-PDMS was characterized by TGA. The vinyl content of copolymer increased with increading D4Vi dosage.In the research of D4/MPS emulsion copolymerization, the influences of the feeding modes, compound emulsifying concentration, KOH concentration, D4concentration, MPS concentration, reaction temperature on emulsion properties were discussed in detail.The results showed that the best condition of copolymerization as follows:the amount of the compound emulsifying agents was4%of D4, the mass ratio of CTAB and OP-10was1:2, the amount of KOH was0.2-0.4%of D4, the amount of D4was20%of the emulsion system, the amount of MPS was2-4%of D4, MPS was added after D4dropping complete and then isothermal reacting2-3h, reaction temperature was80℃. FTIR proved that the copolymerization occurred in D4and MPS. TGA result indicated that the thermal stability of Vi-PDMS may be promoted by grafting appropriate amount of MPS. The vinyl content of copolymer increased with increading MPS dosage and relative error increased correspondingly.