Nanoreactors to Synthesize Well-defined Polymer Nanoparticles: Decoupling Particle Size from Molecular Weight

Sebakhy, Khaled O.; Kessel, Stefanie; Monteiro, Michael J.

doi:10.1021/ma1019889

Cited by 50 publications

(62 citation statements)

References 23 publications

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“…As the radicals are compartmentalized in emulsion polymerization, the rate of polymerization is proportional to the number of particles which can be regulated easily by changing the concentration of surfactants or initiators. Monteiro et al have successfully applied various RAFT agents in water media system, and obtained nanoparticles or functional polymers with controlled particle size and molecular weight distribution [10][11][12]. However, the emulsion polymerizations of these CRP technologies are more complicated and more challenging than that in homogeneous bulk or solution system.…”

Section: Introductionmentioning

confidence: 99%

Emulsion polymerization of styrene using irreversible addition–fragmentation chain transfer agents: effect on the course of the polymerization and molecular weight

Gao

Yan

et al. 2012

Colloid Polym Sci

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The emulsion polymerization of styrene with three different chain transfer agents (CTAs) based on irreversible addition-fragmentation chain transfer (AFCT) mechanism was first reported in this work. The influences of these irreversible AFCT agents on the rate of polymerization, particle size, and molecular weight were investigated. It was found that the intrinsic activity and desorption behaviors of the CTAs determined the efficiency for molecular weight control, rate of polymerization, and particle size in the emulsion polymerization. It has been demonstrated that the rate of polymerization and particle size decreased dramatically in the presence of the irreversible AFCT agents with high chain transfer constant (ethyl α-ptoluenesulfonyl-methacrylate), meanwhile, the molecular weight of the polystyrene could not be controlled well, whereas the irreversible AFCT agents with low chain transfer constant (butyl(2-phenylallyl)sulfane and 2,3-dichloropropene) had a slight effect on the polymerization rate, particle size, and were fairly well for molecular weight control over the whole conversion range in the emulsion polymerization of styrene. The average number of radicals per particle and the number-average molecular weight were calculated by classical radical emulsion polymerization theory, and the experimental results were in good agreement with the results of model calculations, when the irreversible AFCT agents were used as CTAs. The effect of chain transfer agents on the kinetics and nucleation in the emulsion polymerization of styrene can be attributed to desorption of chain-transferred radicals from the polymer particles.The results of this work show that butyl(2-phenylallyl)sulfane as CTA in emulsion polymerization of styrene provides the best balance between the rate of polymerization and the efficiency for molecular weight control conflicting tendencies.

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Section: Introductionmentioning

confidence: 99%

Emulsion polymerization of styrene using irreversible addition–fragmentation chain transfer agents: effect on the course of the polymerization and molecular weight

Gao

Yan

et al. 2012

Colloid Polym Sci

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“…21,22 Various strategies have been proposed to realize well-controlled RAFT polymerizations in aqueous dispersed system and the method of thermoresponsive diblock copolymer nanoreactor reported by Monteiro et al seems especially valid. 23,24 The recent studies tend to use hydrophilic or amphiphilic macromolecular RAFT agent (macro-RAFT agent), which acts as both the macro-RAFT agent and the steric/electrosteric stabilizer, to realize RAFT polymerizations in aqueous dispersed system. [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] For example, emulsion RAFT polymerizations in the presence of the macro-RAFT agents of poly (acrylic acid) trithiocarbonate, 25 poly(acrylic acid)-b-polystyrene trithiocarbonate, 26 poly(ethylene oxide) trithiocarbonate, 27 poly(N,N 0 -dimethylacrylamide) trithiocarbonate, 28 and poly[N- (4-vinylbenzyl)-N,N-dibutylamine hydrochloride] trithiocarbonate 29 have been reported.…”

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confidence: 99%

Aqueous RAFT polymerization of N‐isopropylacrylamide‐mediated with hydrophilic macro‐RAFT agent: Homogeneous or heterogeneous polymerization?

Wang¹,

Li²,

Su³

et al. 2013

J. Polym. Sci. A Polym. Chem.

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Aqueous RAFT polymerization of N-isopropylacrylamide (NIPAM) mediated with hydrophilic macro-RAFT agent is generally used to prepare poly(N-isopropylacrylamide) (PNI-PAM)-based block copolymer. Because of the phase transition temperature of the block copolymer in water being dependent on the chain length of the PNIPAM block, the aqueous RAFT polymerization is much more complex than expected. Herein, the aqueous RAFT polymerization of NIPAM in the presence of the hydrophilic macro-RAFT agent of poly(dimethylacrylamide) trithiocarbonate is studied and compared with the homogeneous solution RAFT polymerization. This aqueous RAFT polymerization leads to the well-defined poly(dimethylacrylamide)-b-poly(N-isopropylacrylamide)-b-poly(dimethylacrylamide) (PDMA-b-PNIPAM-b-PDMA) triblock copolymer. It is found, when the triblock copolymer contains a short PNIPAM block, the aqueous RAFT polymerization undergoes just like the homogeneous one; whereas when the triblock copolymer contains a long PNIPAM block, both the initial homogeneous polymerization and the subsequent dispersion polymerization are involved and the two-stage ln ([M] o /[M])-time plots are indicated. The reason that the PNIPAM chain length greatly affects the aqueous RAFT polymerization is discussed. The present study is anticipated to be helpful to understand the chain extension of thermoresponsive block copolymer during aqueous RAFT polymerization.

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“…These nanoparticles self-assemble at temperatures above their lowest critical solution temperature of ;32°C ( Fig. 2A) to form nanoparticles with a diameter of ;30 nm with a narrow particle size distribution (i.e., the polydispersity index was 0.035) and a Zeta potential close to neutral (20.31 mV) (Urbani and Monteiro, 2009;Sebakhy et al, 2010). When the TDCN were incubated with NAT1, a significant dose-dependent increase in enzyme activity was seen (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The synthesis and characterization of layered double hydroxide (LDH) nanoparticles are reported elsewhere (Musumeci et al, 2010). Thermo-responsive diblock copolymer nanoparticles (TDCN) consisting of poly(dimethylacrylamide) and poly(N-isopropylacrylamide) were synthesized, as previously described (Urbani and Monteiro, 2009;Sebakhy et al, 2010). Transmission electron microscopy was performed, as described previously (Deng et al, 2009).…”

Section: Methodsmentioning

confidence: 99%

Interaction of Human Arylamine N-Acetyltransferase 1 with Different Nanomaterials

et al. 2013

Self Cite

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Humans are exposed to nanoparticles in the environment as well as those in nanomaterials developed for biomedical applications. However, the safety and biologic effects of many nanoparticles remain to be elucidated. Over the past decade, our understanding of the interaction of proteins with various nanomaterials has grown. The protein corona can determine not only how nanoparticles interact with cells but also their biologic effects and toxicity. In this study, we describe the effects that several different classes of nanoparticles exert on the enzymatic activity of the cytosolic protein human arylamine N-acetyltransferase 1 (NAT1), a drug-metabolizing enzyme widely distributed in the body that is also responsible for the activation and detoxification of known carcinogens. We investigated three metal oxides (zinc oxide, titanium dioxide, and silicon dioxide), two synthetic clay nanoparticles (layered double hydroxide and layered silicate nanoparticles), and a self-assembling thermoresponsive polymeric nanoparticle that differ in size and surface characteristics. We found that the different nanoparticles induced very different responses, ranging from inhibition to marked enhancement of enzyme activity. The layered silicates did not directly inactivate NAT1, but was found to enhance substrate-dependent inhibition. These differing effects demonstrate the multiplicity of nanoparticle-protein interactions and suggest that enzyme activity may be compromised in organs exposed to nanoparticles, such as the lungs or reticulo-endothelial system.

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Nanoreactors to Synthesize Well-defined Polymer Nanoparticles: Decoupling Particle Size from Molecular Weight

Cited by 50 publications

References 23 publications

Emulsion polymerization of styrene using irreversible addition–fragmentation chain transfer agents: effect on the course of the polymerization and molecular weight

Emulsion polymerization of styrene using irreversible addition–fragmentation chain transfer agents: effect on the course of the polymerization and molecular weight

Aqueous RAFT polymerization of N‐isopropylacrylamide‐mediated with hydrophilic macro‐RAFT agent: Homogeneous or heterogeneous polymerization?

Interaction of Human Arylamine N-Acetyltransferase 1 with Different Nanomaterials

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