Compartmentalization in atom transfer radical polymerization (ATRP) in dispersed systems

Compartmentalization in atom transfer radical : polymerization (ATRP) in dispersed systems at low conversion (< 10%) has been investigated by means of a modified Smith-Ewart equation focusing on the system n-butyl acrylate/CuBr/4,4-dinonyl-2,2-dipyridyl at 110 degrees C. Compartmentalization of both propagating radicals and deactivator was accounted for in the simulations. As the particle diameter (d) decreases below 70 nm, the polymerization rate (R-p) at 10% conversion increases relative to the corresponding bulk system, goes through a maximum at 60 nm, and thereafter decreases dramatically as d decreases further. This behavior is caused by the separate effects of compartmentalization (segregation and confined space effects) on bimolecular termination and deactivation. The very low RP for small particles (d < 30 nm) is due to the pseudo first-order deactivation rate coefficient being proportional to d(-3).