Direct Synthesis of Controlled-Size Nanospheres inside Nanocavities of Self-Organized Photopolymerizing Soft Oxometalates [PW12 O40 ]n (n=1100-7500).

Abstract

The unusual self-assembly of {(BMIm)2 (DMIm)[PW12 O40 ]}n (n=1100-7500) (BMIm=1-butyl-3-methylimidazolium, DMIm=3,3'-dimethyl-1,1'-diimidazolium) soft oxometalates (SOMs) with controlled size and a hollow nanocavity was exploited for the photochemical synthesis of polymeric nanospheres within the nanocavity of the SOM. The SOM vesicle has been characterized by using several techniques, including dynamic light scattering (DLS), static light scattering (SLS), attenuated total reflection (ATR) IR spectroscopy, Raman spectroscopy, microscopy, and zeta-potential analysis. The self-assembly and stabilization of this soft-oxometalate vesicle has been shown by means of counter-ion condensation. The immediate implication of such stabilization-the variation of the dielectric constant with the hydrodynamic radius of the vesicle-has been used to synthesize vesicles of controlled size. Such vesicles of varying size have been used as templates for polymerization reactions that produce polymeric spheres of controlled size. Direct evidence shows that the SOM behaves as a model heterogeneous catalytic system. Such surfactant- and initiator-free photochemical synthetic routes for obtaining uniform latex spheres could be used in the making of optical bandgap materials, inverse opals, and paints.