Polymerization of styrene in alcohol/water mediated by a macro‐RAFT agent of poly(<i>N</i>‐isopropylacrylamide) trithiocarbonate: From homogeneous to heterogeneous RAFT polymerization

Wang, Xiaohui; Xu, Jianxiong; Zhang, Yaoyao; Zhang, Wangqing

doi:10.1002/pola.26022

Cited by 45 publications

(80 citation statements)

References 62 publications

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“…Figure 4(B) is similar with those reported by Armes and coworkers, 39,40 and it possibly indicates the different monomer conversion before and after particle nucleation. Besides, it is also similar with our previous report on the PNIPAM-TTCmediated RAFT polymerization of styrene in the alcohol/ water mixture, 59 in which both the homogeneous polymerization before particle nucleation and the heterogeneous polymerization after particle nucleation are involved. In the present aqueous RAFT polymerization of NIPAM, it seems more complex.…”

Section: The Effect Of the Molar Ratio Of Macro-raft Agent To Initiatsupporting

confidence: 86%

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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Section: The Effect Of the Molar Ratio Of Macro-raft Agent To Initiatsupporting

confidence: 86%

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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“…There are various studies describing dispersion polymerization syntheses conducted in water/(m)ethanol or water/1,4-dioxane mixtures [42][43][44][45][46][47][48][49][50][51]. However, in this review article we will focus on examples of RAFT dispersion polymerization in the absence of water as a cosolvent.…”

Section: Introductionmentioning

confidence: 99%

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

Derry

Fielding

Armes

2016

Progress in Polymer Science

554

447

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There is considerable current interest in polymerization-induced self-assembly (PISA) via reversible addition-fragmentation chain transfer (RAFT) polymerization as a versatile and efficient route to various types of block copolymer nano-objects. Many successful PISA syntheses have been conducted in water using either RAFT aqueous dispersion polymerization or RAFT aqueous emulsion polymerization. In contrast, this review article is focused on the growing number of RAFT PISA formulations developed for non-aqueous media. A wide range of monomers have been utilized for both the stabilizer and core-forming blocks to produce diblock copolymer nanoparticles in either polar or non-polar solvents via RAFT dispersion polymerization. Such nanoparticles can exhibit spherical, worm-like or vesicular morphologies, often with controllable size and functionality. Detailed characterization of such sterically-stabilized diblock copolymer dispersions provide important insights into the various morphological transformations that can occur both during the PISA synthesis and also subsequently on exposure to a suitable external stimulus (e.g. temperature).

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“…[30][31][32][33] For example, Charleux and co-workers investigated both dispersion and emulsion polymerization formulations for the chain extension of a poly(methacrylic acid-copoly(ethylene oxide) monomethyl ether methacrylate) (P(MAA-PEOMA)) macro-CTA with BzMA in ethanol/water or 1,4dioxane/water solvent mixtures. [30][31][32][33] For example, Charleux and co-workers investigated both dispersion and emulsion polymerization formulations for the chain extension of a poly(methacrylic acid-copoly(ethylene oxide) monomethyl ether methacrylate) (P(MAA-PEOMA)) macro-CTA with BzMA in ethanol/water or 1,4dioxane/water solvent mixtures.…”

Section: Introductionmentioning

confidence: 99%

“…[31][32][33] When using the PNVP stabilizer, styrene was polymerized in the presence of an S,S'-bis(α,α′-dimethyl-α″-acetic acid) trithiocarbonate (BDMAT) RAFT CTA. They investigated both the homopolymerization of styrene in the presence of a PNVP stabilizer and the synthesis of polystyrene-based block copolymer nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Addition of water to an alcoholic RAFT PISA formulation leads to faster kinetics but limits the evolution of copolymer morphology

et al. 2016

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RAFT dispersion polymerization of benzyl methacrylate (BzMA) has been used previously (E. R. Jones, et al., Macromolecules, 2012, 45, 5091) to prepare poly(2-(dimethylamino)ethyl methacrylate)-poly-(benzyl methacrylate) (PDMA-PBzMA) diblock copolymer nanoparticles in ethanol via polymerizationinduced self-assembly (PISA). However, the rate of polymerization was relatively slow, with incomplete monomer conversions being obtained when targeting higher mean degrees of polymerization (DP) even after 24 h at 70°C. Herein we examine the effect of the addition of up to 20% w/w water co-solvent on the kinetics of BzMA polymerization for this PISA formulation. Significantly faster polymerizations were observed: for a target DP of 200, 90% BzMA conversion was achieved within just 6 h in the presence of 20% w/w water, compared to only 35% conversion in anhydrous ethanol under the same conditions. This rate enhancement enables much higher mean DPs to be obtained for the core-forming PBzMA and is attributed to greater partitioning of the BzMA monomer within the particles, which increases the local monomer concentration. However, the presence of water adversely affected the evolution of copolymer morphology from spheres to worms to vesicles when employing a relatively short PDMA chain transfer agent, with only kinetically-trapped spheres being obtained at higher levels of added water. Aqueous electrophoresis studies indicate that the PDMA stabilizer chains acquired partial cationic charge in the presence of water. This leads to more efficient inter-particle repulsion, thus preventing the sphere-sphere fusion events required for an evolution in morphology. In summary, the addition of water to such PISA formulations allows the more efficient synthesis of spherical nanoparticles, but should be used with caution if either diblock copolymer worms or vesicles are desired.This journal is

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Polymerization of styrene in alcohol/water mediated by a macro‐RAFT agent of poly(N‐isopropylacrylamide) trithiocarbonate: From homogeneous to heterogeneous RAFT polymerization

Cited by 45 publications

References 62 publications

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

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

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

Addition of water to an alcoholic RAFT PISA formulation leads to faster kinetics but limits the evolution of copolymer morphology

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