Preparation of Intelligent Microcapsules with Stimuli-Responsive Polymer

Thermo-responsive microcapsules consisted of poly(N-isopropylacrylamide) (poly(NIPAM)) and alginate were prepared using concentric two-fluid nozzle. In this method, poly(NIPAM) and alginate were used as thermo-responsive polymer and structure support polymer, respectively. In the experiment, the solution which contained NIPAM monomer, cross-linking agent and sodium alginate was pumped out from outer nozzle, and the solution which contained cocoa suspension as marker, polymerization initiator and accelerator was pumped out from inner nozzle of the centric two-fluid nozzle to form droplets of double layered structure. The result showed that the obtained capsules had complex structure of poly (NIPAM) and calcium alginate and demonstrated thermo-responsive volume change such that swollen at low temperature and shrunk at high temperature. In addition, pure poly(NIPAM) capsule preparation was tried by removing calcium alginate from the poly(NIPAM)/alginate complex capsule by using chelate agent, EDTA. Resulting capsule showed greater and faster volume change in response to temperature change compared to the original complex capsule. IR analysis confirmed the obtained capsule only contained poly(NIPAM).