| Emulsion polymerization is one of the most important ways to prepare polymer materials. Among various polymer emulsions, the composite polymer emulsion is getting more and more interest especially in industry because of its excellent and well-tailored properties. Acrylates and polysiloxanes are two sorts of important polymers and each of them has their unique characteristics. The preparation of acrylates polymer emulsion modified with polysiloxanes may take advantage of both the properties of polysiloxanes and acrylate polymers. In this paper, two-stage emulsion polymerizhation method was employed to prepare acrylate/polysiloxane composite polymer emulsion using octamethylcyclotetrasiloxane(D4)and acrylates as main monomers. A controlled emulsion was also obtained by blending polysiloxane emulsion and polyacrylates emulsion which were prepared separately. Analysis for the kinetics of polymerization,the particle morphology,structure and the film properties of the final polymer emulsions were carried out. The chemical structures and morphology of the materials surface and bulk were investigated using Infrared analysis technique (FTIR),X-ray photoelectron spectroscopy (XPS),transmission electron microscopy (TEM)and differential scanning calorimetry(DSC). The mechanical and surface properties of the composite latex film were demonstrated through strain–stress and surface contact angle measurement, etc. The main contents and conclusions areas follows:1. Polydimethylsiloxane(PDMS)emulsion was prepared by ring-opening emulsion polymerization of D4 by using dodecyl benzene sulfoacid (DBSA)as emulsifier. Vinyl-containing polysiloxane(PD4MATS) was also obtained by copolymerization of D4 and 3-(trimethoxysilyl) propyl methacrylate (MATS).The kinetics of polymerization showed that the velocity and conversion of the polymerization increased while the particle size decreased as the amount of surfactant increased. The introduction of vinyl-containing siloxane during the ring-opening emulsion polymerization of D4 caused a reduction in both the conversion and the polymerization velocity.Characterization by IR showed that vinyl-containing polysiloxane was successfully obtained by the copolymerization of MATS and D4.2. PDMS and PD4MATS emulsions were employed as seed emulsion to prepare acrylate/polysiloxane composite emulsion by seed emulsion polymerization. The emulsions thereof obtained were stable and had excellent storage time. The experimental results also showed that graft copolymer was successfully prepared by the copolymerization of vinyl-containing polysiloxane (PD4MATS) and polyacrylates(PA) while the unsaturated double bond disappeared after the polymerization.3. The study on the film properties of copolymerization emulsion and blending emulsion of polysiloxane and polyacrylates demonstrated that polysiloxane chains were intended to move to the surface of the latexes film in the course of latex film-formation. The surface tension of the blending polymer(PA+PDMS) was close to that of pure PDMS. The relative silicon content on the latex film surface was much more than the theoretical value, showing a great enrichment of silicon on the surface layer. The surface tension of PAPD4MATS was relatively close to that of pure PA. The XPS results also showed a lower degree of silicon enrichment on the surface layer of PAPD4MATS compared with that of PA+PDMS and PAPDMS.4. With the introduction of PDMS into the PA, the glass transition temperature(Tg)of polyacrylates could shift towards low temperature according to the different phase mixture between PDMS and PA. For the blended polymer emulsions of PA and PDMS, no significant shift was found because of complete phase separation. As for PAPDMS, the partial phase separation between polysioxane and polyacrylates resulted in an obvious shift of the glass transition temperature of polyacrylates. This shift was much more significant for PAPD4MATS in which chemical bonds were formed between polysiloxane chains and polyacrylates chains.
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