The effect of reaction conditions on particle size in dispersion polymerisation

Poly(styrene), poly(methyl methacrylate) and poly(butyl acrylate) dispersions have been prepared in methanolic media using partially hydrolysed poly(vinyl acetate)s, poly(vinyl pyrrolidone), poly(ethylene oxide) and poly(vinyl acetate) as steric stabilisers. The stabiliser concentration, molar mass of the stabiliser, initial solubility parameter of the continuous phase and initiator concentration were varied to investigate the effect that they had on the size of the particles produced. The initial solubility parameter of the continuous phase was varied by using methanol/water mixtures with different compositions. Particle size analysis was carried out by transmission electron microscopy(TEM), in association with image analysis, and laser diffraction particle size analysis. The results showed that dispersions had been produced with particle sizes from O.2-5.4µm in diameter for poly(styrene), from O.I-1.5lµm in diameter for poly(methyl methacrylate) and from O.2-1.8µm in diameter for poly(butyl acrylate). The standard deviation values calculated for the particle size measurements from the dispersions showed that a large number of the dispersions had narrow, or very narrow, particle size distributions... cont'd