Atom transfer radical emulsion polymerization

Recently, atom transfer radical emulsion polymerization (ATRP) of styrene using chloro-terminated poly(ethylene glycol) (PEG-Cl) as maaoinitiator under microwave irradiation was successfully conducted and monodispersed nanoparticles were prepared. In the typical procedure used for ATRP in the presence of CuCl and 2,2 -bipyridine (bipy), styrene, PEG-Cl, and Tween-20 (5wt.%) were dispersed in deionized water, and the mixture was polymerized under microwave irradiation at 75 °C, while a stable dispersion was obtained after 1 h. It was found that the diameters of PEG-b-PS nanoparticles prepared under miaowave irradiation were smaller (<50nm) and more monodispersed than those prepared with conventional heating. 

The controlled emulsion polymerization of styrene using nitroxide-mediated polymerization (NMP), reversible addition-fragmentation transfer polymerization (RAFT), stable free radical polymerization (SFR), and atom transfer radical polymerization (ATRP) methods is described. The chain transfer agent associated with each process was phenyl-t-butylnitrone, nitric oxide, dibenzyl trithiocarbonate, 1,1-diphenylethylene, and ethyl 2-bromo-isobutyrate, respectively. Polydispersities between 1.17 and 1.80 were observed. 

The so-called reverse atom-transfer radical polymerization is feasible in aqueous emulsion too. This system enables the formation of initiating radical species in the water phase with the use of water-soluble initiators such as 1-39, 1-40, and 1-41 as in conventional emulsion radical polymerization.184,249,252,255 The copper-catalyzed emulsion radical polymerization of nBMA afforded polymers with narrow MWDs (MJMn = 1.1—1.4), but the Mn values were much higher than the calculated values due to the termination between the initiating radicals in the aqueous phase.184,255 The emulsions are relatively stable and their particle sizes are around 100—300... 

Controlled free-radical polymerization (CFRP) has been used successfully to produce block, graft, and other controlled architecture copolymers within the last decade for a variety of free radically polymerizable monomers. The main techniques include reversible addition fragmentation and transfer (RAFT) polymerization, stable free-radical polymerization (SFRP) mediated by nitroxide/alkoxyamine based radicals, atom transfer radical polymerization (ATRP), diphenyl ethylene (DPE) mediated polymerization, and novel precipitation/emulsion polymerization based methods like free-radical retrograde precipitation polymerization (FRRPP). ... 

Using an original approach, Zhang and coworkers recently reported the synthesis of PMMA latex particles stabilized by MMT platelets tethered with poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes (Fig. 33) [290]. The PDMAEMA polyelectrolyte brush was synthesized by atom transfer radical polymerization using a cationic initiator previously introduced in the clay galleries. The PDMAEMA-functionaUzed clay platelets were further used to stabilize the emulsion polymerization of MMA initiated by the remaining free radical initiator present on the clay surface. 

Taking into account all of the above mentioned applications, the synthesis of magnetic latex will be discussed in two parts first, the preparation of iron oxide nanoparticles and, second, the preparation of magnetic latex. Depending on the aim of researchers, many polymerization techniques are applied such as suspension, dispersion, emulsion, microemulsion and miniemulsion polymerization in combination with controlled radical polymerization techniques like atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT) and nitroxide-mediated radical polymerization (NMP). The preparation of hybrid magnetic latex by emulsion polymerization will be the focus of this review. 

D. Chan-Seng, M. K. Georges, Living radical emulsion polymerization using the nanoprecipitation technique an extension to atom transfer radical polymerization, J. Polym. Sci., Part A Polym. Chem. 2006, 44, 4027-4038. 

K. Min, H. Gao, K. Matyjaszewski, Development of an ah initio emulsion atom transfer radical polymerization from microemulsion to emulsion, J. Am. Chem. Soc. 2006, 128. 10521-10526. 

Abstract This chapter summarizes the properties and most representative applications of pH-responsive polymers in the biomedical field.The most common methodologies to synthesize pH-responsive polymers such as emulsion polymerization, group transfer polymerization, atom transfer radical polymerization and reversible addition-fragmentation chain transfer polymerization are described. This chapter also discusses the most important applications of pH-responsive polymers in drug and gene delivery and the use of these systems as biosensors, taking into account the chemical and physical properties of these smart polymer systems. 

In this section the most common methodologies used to synthesize pH-responsive polymers are described. Summarizing, they are the emulsion polymerization (micro- and mini-emulsion), controlled living radical polymerization techniques (atom transfer radical polymerization (ATRP),... 

Since chemically grafted SPB show greater stabifity and controllable grafting density, this method of preparation has become more popular than physical adsorption. Chemical methods include photoemulsion polymerization, thermocontrolled emulsion polymerization, atom transfer radical polymerization (ATRP), and reversible addition-fragmentation chain transfer (PJVFT). 

Okubo, M., Minami, H., Zhou, J. Preparation of block copolymer by atom transfer radical seeded emulsion polymerization. CoUoid Polym. Sci. 282(7), 747-752 (2004)... 

Polymerization of emulsion SBR is started by free radicals generated by the redox system in cold SBR and by persulfate or other initiator in hot SBR. The initiators are not involved in the molecular structure of the polymers. Almost all molecules are terminated by fragments of the chain transfer agent (a mercaptan). Schematically, the molecules are RSM H. where RS is the C H S pan of a dodccyl mercaptan molecule M is the monomer involved n is the degree of polymerization, and H is a hydrogen atom formerly attached to the sulfur of a mercaptan. In the case of free-radical-initiated polymerization of butadiene, by itself to form homopolymers or with other monomers for fonn copolymers, the butadiene will be about 18% 16% fix-1.4 and 66% trms-1,4-... 

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