(255co) Polyvinyl Alcohol (PVA) As Protective Colloid for Polystyrene Nanoparticles Synthesis Initiated By Oil-Soluble Initiator

Compared
with low molecular surfactants, polyvinyl alcohol (PVA) could afford latexes
with particular tackiness as an important property for various applications.
However, until now, except for some highly reactive monomers, most of monomers
including styrene seldom use PVA as protective colloid in emulsion
polymerization due to the lack of its stability. In this work, we used
oil-soluble initiator, 2,2¡¯-azobisisobutyronitrile (AIBN), to accelerate the emulsion
copolymerization of styrene and divinyl benzene in PVA colloids and synthesize polystyrene
(PS) nanoparticles within 50 min at 70 ^oC successfully.
Even at the monomer-to-water ratio as high as 4:1, the emulsion system could keep
stable throughout the emulsion polymerization with only PVA as stabilizer, and
the polymerization in PVA colloids was always dominant. The adjustment of the size
of the PS nanoparticles in the range from 70 nm to 100 nm was achieved simply
by changing the polymerization temperature, the addition of PVA, or the
monomer-to-water ratio. The PVA adhering on
the surface of the PS nanoparticles showed stable modification effect in the
aqueous latexes, and also could be washed completely by dimethylsulfoxide
(DMSO) to obtain PS nanoparticles without surfactant contaminant. This
method was also exploited to synthesize poly(styrene-co-methyl methacrylate)
and poly(styrene-co-4-chlorostyrene) nanoparticles, possessing good potentials
in functional polymeric nanoparticles production with the advantages of high capacity
and broad applicability.