11/26/2010
pH/temperature dual stimuli-responsive microcapsules with interpenetrating polymer network structure
(1723-1729)   Colloid and Polymer Science 288 #18 (2010)
Xing et al of Donghua University, China used a three step process to fabricate microcapsules with interpenetrating polymer network (IPN) structure based on crosslinked poly (N-isopropylacrylamide) (PNIPAM) and crosslinked poly (acrylic acid).  First the silica/PNIPAM core/shell composite particles were synthesized by thermo-initiated seed precipitation polymerization.  Secondly, PAA network was incorporated into the shell of the composite particles by redox-initiated polymerization of acrylic acid and MBA entrapped in the PNIPAM network.  Finally, the silica core of the composite particles was removed using hydrofluoric acid resulting in hollow, empty microcapsules.  (RDC 11/23/2010)