Making particle size library of polystyrene latexes prepared through surfactant-free emulsion polymerization: from nano to micronsize

Polystyrene latexes where the stabilizing moiety originated from I) the inistab (initiator + stabilizer), 4,4'- Azobis(4-cyanopentanoic acid) (ACPA), II) acrylic acid (AA) (in situ copolymerized) or/and III) previously synthesized poly(acrylic acid)-block-polystyrene (PAA-b-PS) were prepared via surfactant-free emulsion polymerization (SFEP). This attitude of incorporating the sodium carboxilate groups (COO−Na+) as negatively charged stabilizing moieties in different materials yield quite different nucleation mechanism. Therefore, the different particle size would be expected. The average size of latex particles were ranged from 1.3 micron to 50 nm. Using ACPA as the only stabilizer produced latexes that were ranged from 200 nm to 1.3 micron. In contrast, when the stabilizing moieties originated from PAA-b-PS, the latexes exhibited the size below the 100 nm. By combining the use of both in situ polymerized ACPA inistab, AA monomer with/without PAA-b-PS, we were able to produce latexes with tunable polystyrene particle sizes.