The Properties And Applications Of Monochlormethyl-heptamethycyclotetrasiloxane

Carbon-Functional Organosilicon Compounds are these ones that certain carbon-functional groups are introduced in organosilicon polymers. Organosilicon materials with carbon-functional groups which have new physical and chemical properties own extremely important value either in theory or in practical industrial production. In this paper, active groups were introduced in Octamethylcyclotetrasiloxane(D₄) by substitution of chlorine atom, monochlormethyl-heptamethycyclotetrasiloxane(D4Cl) was obtained and then carbon-functional groups such as carboxyl, ether group were introduced in organosilicon polymers with phase transfer catalyst by chlorine atom under mild conditions. By this way, the amphiphilic copolymer was obtained to improve the hydrophobicity of organosilicon. Furthermore properties of D₄Cl were studied extensively. Drug immobilization and microemusion polymerization about D₄Cl were investigated. Atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out, organosilicon compounds with chlormethyl groups as initiators. The copolymer of organosilicon and MMA may be used to improve mechanical properties of organic silicon rubber. Meanwhile the good properties of organosilicon were introduced to carbon polymers. The main work and conclusions as following.First, the bulk polymerization kinetics of D₄Cl monomer with concentrated sulfuric acid as catalyst was investigated, and the effects of temperature and catalyst concentration on the polymerization rate were studied. The results show that the polymerization rate increases with increasing of temperature and catalyst concentration, and the activation energy is calculated out to be 40.37 kJ·mol^-1 . But the increasing trend of polymerization rate constant becomes weaker with increasing of catalyst concentration. Compared with the cationic ring-opening polymerization of D₄, the activation energy of D₄Cl is higher, but its polymerization rate is lowered, which means electron withdrawing groups affect the polymerization rate obviously. Second, the reactivity of C-Cl bond in D₄Cl was investigated. Fluorouracil was added by chemical bond to poly(monochlormethyl-heptamethycyclotetrasiloxane) under a condition of base as catalyst. Functional groups substitution reactions were carried out successfully between potassium acetate and D₄Cl with phase transfer catalyst and a polymer with relevant carbon-fucntional group was obtained eventually by base catalyzed. So do p-bromophenol and p-hydroxybenzaldehyde and relevant polymers with certain functional groups were obtained. The results show that the reactivity of C-Cl bond can be stimulated under a proper condition.Third, the phase behavior of D₄Cl /CTAB/glycol/water pseudo-ternary system was studied and the pseudo-ternary phase diagram under 80 88888 was obtained. The microemulsion polymerization was carried out according to some proper material ratios and polyorganosiloxane particles with diameter in 50 nm were obtained. The antifoam performance of the microemulsion was also investigated and the result was perfect.Finally, atom transfer radical suspension polymerizations of MMA was carried out. D₄Cl and poly(monochlormethyl-heptamethycyclotetrasiloxane) as initiators respectively, CuCl/bpy as catalyst and poly(methyl methacrylate)(PMMA) with end of cyclic siloxane and a centipede-like polymer with polysiloxane as main chain and PMMA as branch chain were obtained, which polydispersities of the polymers were small(1 .3-1.4) and molecular weight was 800 thousand or so.The innovations of this paper as follow.(1) The pseudo-ternary phase diagram and microemusion polymerization of D₄Cl have never been reported and a kind of perfect defoamer with good antifoam performance was obtained.(2) It is first reported to use D₄Cl monomer and polymer as initiators in ATRP and the molecular weight of polymer by this way can be huge to 800 thousand but the polydispersities of the polymers were small(1.3-1.4).