Thermally Responsive PM(EO)2MA Magnetic Microgels via Activators Generated by Electron Transfer Atom Transfer Radical Polymerization in Miniemulsion

• Published in: Chemistry of materials Vol. 21; no. 17; pp. 3965 - 3972
• Main Authors: Dong, Hongchen, Mantha, Venkat, Matyjaszewski, Krzysztof
• Format: Journal Article
• Language: English
• Published: American Chemical Society 08.09.2009
• Subjects: Bio- (and Biomimetic) Materials; Magnetic Materials; Polymeric Materials
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm901143e

Activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) of di(ethylene glycol) methyl ether methacrylate (M(EO)2MA) was successfully conducted in miniemulsion at 65 °C. The reaction system was stable without diffusion of monomer and polymer into the aqueous phase because the monomer is water-insoluble and PM(EO)2MA becomes hydrophobic above 25 °C. The polymerization was well-controlled with a mild water-soluble reducing agent, hydrazine, yielding PM(EO)2MA homopolymer with narrow molecular weight distribution (M w/M n = 1.2−1.6). Using this technique, well-defined PM(EO)2MA microgels were prepared with degradable disulfide cross-linker. The microgels became magnetic after physically loading oleic acid-coated Fe3O4 nanoparticles, which could not diffuse out of the microgels due to their hydrophobicity. Thermally responsive and drug loading−releasing behavior of the magnetic microgels was studied using Rhodamine B as a model for hydrophilic drugs. The drug releasing behavior can be well-controlled by both temperature and addition of reducing agent, indicating that the PM(EO)2MA magnetic microgels could find potential application for controlled targeted drug delivery.