Emulsion polymerization of vinyl acetate by urethane based surfactant and high solid content water-based emulsion polymerization of acrylic monomers

Emulsifiers, another name are surfactants, are characterized by a chemical structure comprising a hydrophilic group having one and/or two hydrophobic flexible alkyl chains of a certain length. In small quantities dispersed in the aqueous phase, the surfactant is adequate for self-assembly into the micelle micro aggregates. Surfactants are used in several areas for different purpose such as painting, emulsion polymerizations, adhesives, textile industry, etc. Surfactants are divided into four main categories. They are anionic, cationic, non-ionic and zwitterionic. In this study, a new nonionic polymeric surfactant (PU) has been synthesized with the reaction between Poly(ethylene glycol) dimethyl ether (PEG500) and Toluene 2,4-diisocyanate (TDI). The polymeric surfactant was characterized by using FT-IR spectroscopy, GPC, critical micelle measurements via tensiometer. Critical micelle concentration of PU was determined by surface tension measurements. This value was calculated as 0.68x10 mg / mL. Molecular weight of the PU was determined by gel permeation chromotography (GPC). Mw, Mn and Mz molecular weight was measured as respectively 1361, 1163 and 1524 g / moles. Polydispersity index was obtained as 1.171 . PU was used emulsion polymerization of vinyl acetate and copolymerization of metyl methacrylate and butyl acrylate depending on surfactant quantity and time. Obtained latexes was characterized by particle size measurements, viscosity and surface tension measurements. In addition, molecular weight of the polymers were determined by GPC. High solid content water-based emulsion polymerization studies were performed in the another part of the thesis. Latexes produced by emulsion polymerization are versatile materials. It extensively used in very different industry such as adhesives, coatings, textiles, paper paints, floor polish and makeup. The solids content of the latexes produced in the industry is between 50-55%. High solids content (HSC) brings many advantages, such as maximizing reactor production, minimizing transportation and storage costs, providing greater flexibility in product formulation and improving surface coverage when applied. The increase in solids content negatively affects the latex viscosity. This also affects the heat removal rate, mixing ability, mass transfer and product stability. The way to obtain low viscosity (HSC / LV) high solids content is achieved by controlling the particle size distribution (PSD). Particles in a perfect monodisperse latex will contact the solids content of about 64% theorically. This explains that most industrial processes with relatively narrow particle size distribution generally operate at less than 55% by weight of solids content. Bimodal particle size distribution production is considered to come from above this limitation and to achieve the goals of high solids content and low viscosity. In this thesis, two different methods were used to produce twelve different high solid content emulsion polymerization. Firstly 42 nm seed emulsion was prepared by semi-continuous polymerization. Seed emulsion was grown with pre-emulsion via feeding. After the firstly added seed is required to grow, a precise amount of seed was introduced into the reactor shot wise, keeping the feeding of monomers, surfactant and ammonia to reach the desired solids content. Secondly, primary seed was not used in second method. The rest of experiment conditions are same with first method. 65% solid content latexes are obtained. The latexes were characterized by using, Brookfield viscometer, tansiometer, Zetasizer Nanaoseries NS. Unimodal particle size distributions were obtained at the final product that is produced with first method. Viscosities of these products are quite high, compared with other method. The surface tension of these products raise with increasing solid content. Another products which are produced second method, has bimodal particle size distribution. Viscosities of these products are quite low, due to bimodality. The surface tension of these products has nearly same values because of surfactant amount. To sum up, high solid content low viscosity bimodal and unimodal particle size distribution emulsion polymers were synthesized.