Dear colleagues! I had to yield polystyrene particles of specified size 50-100 μm (at least 60-80% mass of initial monomer) by means of one-stage polymerization. I have chosen to utilize suspension polymerization in presence of polyvinyl alcohol (Mowiol 18-88) as stabilizer and partially succeed. But still I have no clue how to solve some problems:
1) Sometimes I can't reach 50-100 μm size, and most of time my main fraction consisted of 100-250 μm particles. I suppose I just used slow-rate stirrer.
2) Forming of microparticles (d < 30 μm or even about 1-2 μm, maybe), which yield can reach more than 60 % mass of initial monomer, whereas target fraction (50-100 μm) yeild is only about 25 % mass. I have no idea how these particles are formed, because styrene is hardly soluble in water media and I use benzoyl peroxide as initiator, so it must not be soap-free polymerization (it takes place while using water-soluble initiators, like potassium persulfate). Also PVAlc concentration in water doesn't exceed 0.2-1 % mass.
Unfortunately I don't know all aspects of suspension polymerization. Could your reccommend me some books or articles for solving these issues?
P.S. Also these particles must be soluble in organic solvents, so using of divinylbenzene as crosslinking agent is not allowed.
Try to play with the concentration of the monomer and concentration with PVOH.
Try to stop the polymerization during different times and see the results.
Nedal abu-thabit Thank you for your recommendation! We tried to change both of these parameters, we can't get smaller particles than 100 μm. So we tried to use very little concentration of monomer (1 volume part of styrene to 20 volume parts of PVOH water solution), but these caused "milk" (microparticles) formation
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