Synthesis, Structure And Properties Of Acrylate / Siloxane Copolymer Emulsion

It is well known that polyacrylate and polysiloxane have been widely used in many fields by virtue of their many specific properties respectively. The combination of polyacrylate with polysiloxane should be of importance and interest in view of both scientific researches and industrial applications. In this paper, the preparation, characterization, and properties of the copolymer latexes of polyacrylate-siloxane and the films cast from original latexes were studied in detail. Also, the novel latex particles with polyacrylate as core and with polysiloxane as shell got from one-step polymerization which was totally different from seeded emulsion polymerization were prepared for the first time. The copolymer latex was prepared from butyl acrylate (BA), octamethyl tetracyclosiloxane (D4) and methacryloxypropyl trimethoxysilane (MATS) by using monomer emulsion and initiator addition processes simultaneously and ammonia persultate (APS) and dodecylbenzene sulphenic acid (DBSA) as initiator-catalyst system at 85 C. It was found that the latexes adjusted to pH 7 do not cross linking when maintaining, and will cross linking gradually after the formation of copolymers or films. The solubility coefficient of this copolymer was investigated, about 9.7 cal1/2/cm3/2. The structure of copolymers was verified by Soxhlet extraction, spectra of FTIR and DSC The analysis of dynamics gave light to the mechanism of the copolymerization, that is, free radical polymerization of acrylate carries out firstly, while cationic ring-opening and step polymerization of cyclosiloxane takes place secondly. It was discovered it was the main reason that led to the core(PA)/shell(PSi) structure. However, the existence of inverted core/shell structure was inevitable because of the thermodynamic factor. All those were characterized by transmission electron microscope using RuO4 as staining agent.