MAGNETICALLY-RESPONSIVE MICROPARTICLES WITH IMPROVED RESPONSE TIMES

摘要

Magnetically responsive particles can include two or more magnetically responsive layers (“MRL”). As such, the particles can have the following: a polymeric core; a first magnetically responsive layer (“MRL”) on the core; a first polymeric layer bound to the first MRL; a second MRL layer bound to the first polymeric layer; and a second polymeric layer bound to the second MRL. The particles can have a faster magnetic response time compared to a similar particle having only a single MRL, which can be at least 25% faster. Also, the particle can have a magnetic squareness of less than about 0.1. Preferably, the particle can have negligible residual magnetism after being exposed to a magnetic field sufficient for the particle to respond thereto. Further, the particle can be colloidally stable in water at concentrations from about 0.1 to 10 grams of particle per 100 milliliters of water.