NANOSIZE LIPOPHILIC POLYACRYLATE PARTICLES AND THEIR PHOTOINDUCED FLOCCULATION IN HYDROCARBON SOLVENTS

The synthesis, characterization, and proper,ies of colloidal nanostruc tures in hydrocarbon media are reported. These sterically stabilized s tructures are unusual in that the stabilizing arms are attached to the particle by photoactive groups, and the arms can be cleaved through i rradiation, leading to photoinduced flocculation. In the first step of the synthesis, cross-linked poly(butyl methacrylate) (PBMA) latex par ticles with controlled functionality (-COOH and -OH groups) were prepa red by emulsion polymerization. The purified PBMA latex was neutralize d with Cs2CO3 and then transferred to an organic medium (dimethylforma mide), where it was converted to lipophilic nanoparticles through chem ical modification with 2-bromo derivatives of long-chain 1-phenylalkyl ketones or nitrobenzyl ether derivatives of polyisobutylene, The part icles can be dispersed in hydrocarbon solvents. Irradiation leads to f locculation, except that in the presence of hydrocarbon-soluble polyme rs bearing amino groups, the unprotected particles can be intercepted and flocculation inhibited. These particles serve as an interesting mo del for precursors to sludge formation in motor oil.