The development of microgels/nanogels for drug delivery applications

Chemical Reviews is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 “Green” Atom Transfer Radical Polymerization: From Process Design to Preparation of Well-Defined Environmentally Friendly Polymeric Materials Nicolay V. Tsarevsky, and Krzysztof Matyjaszewski Chem. Rev., 2007, 107 (6), 2270-2299• DOI: 10.1021/cr050947p • Publication Date (Web): 27 May 2007 Downloaded from http://pubs.acs.org on April 2, 2009

"Green" atom transfer radical polymerization: from process design to preparation of well-defined environmentally friendly polymeric materials.

Hydrogels for biomedical applications.

International Tables for X-Ray Crystallography (Published for the International Union of Crystallography.) Vol. 1: Symmetry Groups. Edited by Norman F. M. Henry and Kathleen Lonsdale. Pp. xi + 558. (Birmingham: Kynoch Press, 1952.) 105s.

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International Tables for X-Ray Crystallography

2.6. Microemulsion Polymerization 3778 2.6.1. General Considerations 3778 2.6.2. Microemulsion NMP 3778 2.6.3. Microemulsion ATRP 3778 2.6.4. Microemulsion RAFT Polymerization 3779 2.6.5. ITP in Microemulsion 3779 2.7. Dispersion and Precipitation Polymerizations 3779 2.7.1. General Considerations 3779 2.7.2. NMP 3780 2.7.3. ATRP 3781 2.7.4. RAFT 3782 2.7.5. Dispersion ITP 3782 3. Cross-linking CLRP in Dispersed Systems 3783 3.1. General Considerations 3783 3.2. Cross-linking NMP 3783 3.3. Cross-linking ATRP 3784 3.4. Cross-Linking RAFT Polymerization 3784 3.5. Cross-Linking ITP 3784 4. Particle Morphology 3785 4.1. General Considerations 3785 4.2. Core-Shell Particles 3785 4.3. Hollow Particles 3785 4.4. Multilayered Particles 3786 5. Conclusions and Outlook 3787 6. List of Abbreviations 3788 7. Acknowledgments 3789 8. References 3789

Controlled/living radical polymerization in dispersed systems

Emulsion atom transfer radical polymerization of 2-ethylhexyl methacrylate

The emulsion atom transfer radical block copolymerization of 2-ethylhexyl methacrylate (EHMA) and methyl methacrylate (MMA) was carried out with the bifunctional initiator 1,4-butylene glycol di(2-bromoisobutyrate). The system was mediated by copper bromide/4,4'-dinonyl-2,2'-bipyridyl and stabilized by polyoxyethylene sorbitan monooleate. The effects of the initiator concentration and temperature profile on the polymerization kinetics and latex stability were systematically examined. Both EHMA homopolymerization and successive copolymerization with MMA proceeded in a living manner and gave good control over the polymer molecular weights. The polymer molecular weights increased linearly with the monomer conversion with polydispersities lower than 1.2. A low-temperature prepolymerization step was found to be helpful in stabilizing the latex systems, whereas further polymerization at an elevated temperature ensured high conversion rates. The EHMA polymers were effective as macroinitiators for initiating the block polymerization of MMA. Triblock poly(methyl methacrylate-2-ethylhexyl methacrylate-methyl methacrylate) samples with various block lengths were synthesized. The MMA and EHMA reactivity ratios determined by a nonlinear least-square method were ∼0.903 and ∼0.930, respectively, at 70 C.

Emulsion atom transfer radical block copolymerization of 2-ethylhexyl methacrylate and methyl methacrylate

In this study, the effect of various polymerization conditions on the shape of the particles produced by dual-seeded dispersion polymerization of a second monomer with polystyrene (PS) and poly(methyl methacrylate) (PMMA) seed particles in the presence of saturated hydrocarbon droplets in a polar media was discussed. It was observed that with changing the affinity between the hydrocarbon and PS seed particles, second monomer type, polarity, and alcohol type of the medium nonspherical particles with a variety of shapes can be produced. Furthermore, we suggested that the presence of PMMA seed particles in the medium affects the distribution of the second polymer domains on the surface of the PS seed particles in addition to the absorbed amount of the hydrocarbon by PS particles and second polymer domains and the distribution of the hydrocarbon between them. Moreover, the experimental results showed that almond shell-like PS particles can be prepared under certain conditions.

Preparation of nonspherical particles via dual-seeded dispersion polymerization in the presence of saturated hydrocarbon droplets

In this study, the preparation of various methacrylic particles with monodisperse size via dispersion polymerization in polar media was discussed. The effect of various polymerization conditions such as polarity of the medium, monomer, stabilizer, and initiator concentration, polymerization temperature, and initiator type on the size and size distribution of these particles was evaluated. The experimental results showed that, with a decrease in the difference between medium solubility parameter (MSP) and polymer solubility parameter (PSP), stabilizer concentration and with an increase in monomer content size of the particles increased and size distribution of them became broader. The obtained results showed that the particle size and size distribution of various polymers were different functions of initiator concentration. It means that, for the production of monodisperse particles, specific amount of initiator is needed for each type of the polymers. Moreover, it was observed that the size and size distribution of the particles with higher polarity were more sensitive to changing the polarity of the medium, and the size distribution of the particles with lower glass transition temperature (T
 g) is more sensitive to changing the stabilizer concentration which is because of less stability of them. Furthermore, to our surprise, the obtained results showed that, in MSP-PSP of 18.5 MPa0.5, size and size distribution of all types of the particles became equivalent.

Generalizing the polymerization conditions for the production of monodisperse polymeric particles via dispersion polymerization

In this work, we present a novel synthesis method for the preparation of micron-sized, monodisperse polymeric nonspherical particles without changing the shape of a precursor. In this technique, which we called micromolding–polymerization, nonspherical particles of second polymer were formed directly on the surface of micromolds (solvent-swollen polymeric particles). The experimental results showed that the affinity between the second polymer and micromolds, and size and concentration of the oligoradicals specify the shape of the particles.

Hormoz Eslami

Papers

Emulsion atom transfer radical polymerization of 2-ethylhexyl methacrylate

Emulsion atom transfer radical block copolymerization of 2-ethylhexyl methacrylate and methyl methacrylate

Preparation of nonspherical particles via dual-seeded dispersion polymerization in the presence of saturated hydrocarbon droplets

Generalizing the polymerization conditions for the production of monodisperse polymeric particles via dispersion polymerization

Preparation of micron-sized, monodisperse polymeric nonspherical particles with tunable shapes by micromolding–polymerization