20/12/2017 · Radiation synthesis of PNIPAM ..
the synthesis of magnetic PNIPAM has ..
In the present study we report a facile and reproducible method of preparing magnetic thermosensitive hybrid material based on P(NIPAM) microgels covered with γ-Fe2O3 nanoparticles of 6-nm size. The iron oxide nanoparticles provided magnetic response to the microgels. In addition, the presence of the magnetic nanoparticles on the microgels altered their swelling behavior and shifted their volume phase transition temperature to higher values. In particular, for inorganic shells with 18% (w/w) of magnetic nanoparticles the volume phase transition of the microgels was shifted from 36 to 40 °C. In contrast, for shells consisting of 38% (w/w) magnetic nanoparticles the volume phase transition of the microgels was almost blocked, thus indicating that the microgel thermal response was strongly affected by the presence of the inorganic nanoparticles. The synthesized thermosensitive magnetic microgels are envisaged to be ideal for potential applications as thermosensitive targeted drug delivery systems.
PNIPAM hydrogel is a typically temperature-sensitive ..
Poly(-isopropylacrylamide) (PNIPAM) hydrogel microcapsules having a hydrophobic corona (MCs) were prepared by precipitation−polymerization performed in water-in-oil emulsion using polyethyleneoxide−polyisoprene block copolymer as macromolecular surfactant and a corona-forming compound. The resulting hydrogel MCs form stable dispersions even in highly apolar organic solvents, such as cyclohexane, but flocculate in water. An approach to load the MCs with water, based on addition of aqueous solutions to the dispersion of the MCs in THF followed by addition of apolar solvents to induce segregation of a water-rich phase, was developed. The water-filled hydrogel MCs show a well-pronounced swelling/deswelling transition triggered by temperature in an environment that contains only minute amounts of water. Encapsulating capabilities of the MCs were also demonstrated. The MCs can be envisaged for applications that require controlled dispersion and release of hydrophilic species in oils.