Cl. Zhou et al., Synthesis and characterization of nonaqueous dispersion particles with photolabile alpha-heptadecylphenacyl ester stabilizer chains, J POL SC PC, 39(15), 2001, pp. 2642-2657
Citations number
26
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
We describe a new method for the synthesis of core-shell photolabile nanopa
rticles. The synthesis begins with the batch emulsion copolymerization of n
-butyl methacrylate (BMA) and ethylene glycol dimethacrylate to form small
(20-nm-diameter) crosslinked particles with a narrow size distribution. The
se seeds are then used for a second-stage emulsion copolymerizations in whi
ch BMA and various polar monomers, including methacrylic acid, are added un
der monomer-starved conditions. After characterization of the particles, th
ey are transferred to an N,N-dimethylformamide solution. The cesium salt of
the carboxylic acid groups is reacted with 2-bromo-1-phenyl-octadecan-1-on
e to convert various fractions of the -COOH groups to the corresponding 2-b
enzoylheptadecyl ester groups. These aliphatic ester groups render the surf
ace sufficiently hydrophobic that the particles can be dispersed in common
aliphatic hydrocarbons solvents to yield colloidal dispersions, sterically
stabilized by the dangling aliphatic chains. Ester groups with a phenyl ket
one attached to the P-carbon are photolabile. Irradiation of the particles
with W light detaches the sterically stabilizing chains from the particle a
nd transforms the surface groups back to COOH groups. This leads to floccul
ation of the particles. The emphasis in this article is on the optimization
of the particle synthesis and the characterization of the particles obtain
ed. (C) 2001 John Wiley & Sons, Inc.