Copolymerization forced gradient

Forced gradient copolymerization using continuous feed or semibatch techniques... 

The MMA/S nitroxide-mediated copolymerization system was further studied on a theoretical basis using kinetic Monte Garlo simulations, under batch or forced-gradient conditions. The effect of the deactivation reaction on the segment length and length distribution was studied and it was conduded that the theory used for classical radical copolymerization does not always hold in GLRP. ... 

The expansion of dispersed media ATRP to microemulsion provided the critical step required for development of a process for addition of pure monomer to the system to increase the percent solids in the final latex. This procedure was initially employed to prepare a forced gradient copolymer in a heterogeneous controlled copolymerization since the added pure monomer could diffuse to the latex partides containing all components required for an ATRP. An extension of the concept resulted in the development of an ab initio emulsion polymerization process, capable of directly preparing a stable latex containing block copolymers. The critical requirement for this advance in dispersed media ATRP was the ability to encapsulate all agents required for an ATRP in the initially formed micelles. This allowed pure monomer to be added to the reaction medium. The added monomer was then able to diffuse to the active micelles, allowing an increase in micelle size and concomitant increase in the percent solids and decrease in percent surfactants in the system. 

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