مرجع تخصصی کتب و نشریات الکترونیکی

Abstract:

The mechanism for the formation of amphiphilic coreeshell particles in water is elucidated via a kinetic astudy of semi-batch polymerization of methyl methacrylate (MMA) grafted from polyethylenimine (PEI) initiated with tert-butyl hydroperoxide in an emulsion polymerization.

The monomer conversion,the polymerization kinetics,the particle size,the particle number density,the poly(methyl methacrylate) (PMMA) core diameter,the percentage of unbound PEI,and the grafting efficiency of PMMA were determined at various times during the polymerization.

The particle number density and the percentage of unbound PEI were almost independent of the controllable variables.

The particle sizes and the core diameters increased with each consecutive batch of monomer addition,while the grafting efficiency of PMMA decreased.

These data supported the hypothesis that the PEI-g-PMMA graft copolymers were formed early in the polymerization and later self-assembled to a new phase,micellar microdomains.

These microdomains act as loci for subsequent MMA polymerization as the monomer is fed into the reaction,without subsequent formation of new particles.

The size of the resulting highly uniform coreeshell particles (99e147 nm) can be controlled by choosing the amount of monomer charged.

Thus,this polymerization method is viable for a large scale production of coreeshell particles with high solids content.


Published by the journal of: Polymer
Publication Date: 2010
Keywords: Polyethylenimine,Graft polymerization,Amphiphilic coreeshell particles