Effect of Solvent Concentration to the Preparation of Polystyrene Nanoparticles Using Polyelectrolyte Block Copolymer
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0947-A03-72
Effect of Solvent Concentration to the Preparation of Polystyrene Nanoparticles Using Polyelectrolyte Block Copolymer Edwin Doronila Garcia, Youngjin Choi, Hyeongmin Moon, and Bumsuk Jung Department of Environmental Engineering and Biotechnology, Myongji University, Yongin City, 449-728, Korea, Republic of Abstract Particles of sizes within the nano region have attracted many applications in different fields of science. In this study, the self assembly property in a selective solvent of block copolymers has been used for the preparation of polystyrene nanospheres. Sulfonated Styrene–Butadiene-Styrene (SSBS) tri block copolymer was used as a polymeric surfactant for synthesis of uniformly sized polystyrene nanoparticles using emulsion polymerization. The effects of initiator, monomer and block copolymer concentration to the molecular weight distribution and size distribution were investigated. Uniformly sized nanoparticles with a polydispersity index of 1.004 and diameter of 112.9nm was verified by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM), respectively. Using a mixed continuous phase solution of water and methanol, it was found out that the particle size decreased relative to the increase of methanol added to the reaction solution. Associating behavior of the polyelectrolyte block copolymer in the binary solvent environment regarding size of micelle formed was reflected on the properties of the nanospheres. Nanoparticles prepared with greater methanol concentration were observed to be more or less than 100 nm. Size distribution was also observed to be narrower in proportion to MeOH concentration. Introduction Polyelectrolyte block copolymers are known to possess self assembling properties especially in selective solvents for one of the blocks [1]. One known and established application of these properties is as the stabilizer in emulsion polymerization in preparation of spherical particles in the nanometer range [2]. The polyelectrolyte forms spherical micelles that act as the locus of reaction during polymerization. The properties of these spherical micelles can be modified by changing the solvent selective to one of the blocks [3]. In the present study, the contributions of each component of the emulsion polymerization recipe to the molecular weight, size and size distribution of the prepared polystyrene nanoparticles using data analyzed from Gel Permeation Chromatography (GPC), Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM) were investigated. Also, the associating properties of the sulfonated block copolymers in the presence of another solvent by observing any change in size and size distribution using SEM analysis. The effect of using a monomer which can dissolve one block of polymeric surfactant as well as a soluble in the continuous phase to size and size distribution was studied.
Experimental Details 1,4 – Dioxane extra pure from Junsei Chemicals, Chlorosulfonic acid from Kanto Chemicals, Potassium persulfate from Aldrich were used as received.
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