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

Wang, Xiaohui; Li, Shentong; Su, Yang; Huo, Fei; Zhang, Wangqing

doi:10.1002/pola.26599

Cited by 17 publications

(23 citation statements)

References 60 publications

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“…2C. 52,53 The complete disappearance of the resonance signal at 1.75 ppm in 1 H NMR spectrum of PU-g-PDMA implied that all trithiocarbonate-based RAFT chain-transfer agent lateral groups on fPU have taken part in the graft copolymerization reaction. Therefore, the graft density of the obtained graft copolymer was equal to the amount of RAFT groups on fPU backbone.…”

Section: Synthesis Of Pu-g-pdma Copolymermentioning

confidence: 97%

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Yuan

Gao

et al. 2016

RSC Adv.

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A robust method for the synthesis of the well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) (PU-g-PDMA) copolymers with a good control over the graft density and the grafted chain length was presented in this study. Firstly, functional polyurethane (fPU) polymer with trithiocarbonate-based chain transfer agent lateral group was synthesized by the polyaddition reaction of 2,2-bis(hydroxymethyl)butyl 2-(ethylthiocarbonothioylthio)-2-methylpropanoate (BEMP) with hexamethylene diisocyanate (HDI), and the subsequent chain extension reaction with 1,4-butanediol (BDO). The content of the chain-transfer groups in the synthesized fPU could be well tuned by altering the mole ratio of BEMP to HDI during the synthesis of prepolymer. The produced fPU was then applied as the macro-RAFT to mediate the radical polymerization reaction of the N,N-dimethylacrylamide (DMA) monomers that were initiated by azobisisobutyronitrile (AIBN), resulting in well-defined amphiphilic PU-g-PDMA graft copolymers with a known graft density and tunable grafted chain lengths. The structure of the obtained PU-g-PDMA was characterized carefully by FTIR and 1 H NMR. The average molecular weight and polydistribution of PU-g-PDMA copolymers were analyzed by GPC. The thermal properties of fPU and PU-g-PDMA copolymers were investigated by differential scanning calorimetry (DSC) and themogravimetric analysis (TGA). The amphiphilic PU-g-PDMA graft copolymers could self assemble into spherical nanoparticles with a core-shell structure in water. The core-shell structure nanoparticles could be applied as emulsifiers for the formation of stabilized toluene in water Pickering emulsion, and an extremely low content of emulsifiers (~0.01%) relative to the total weight of oil and water was required.

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Section: Synthesis Of Pu-g-pdma Copolymermentioning

confidence: 97%

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Yuan

Gao

et al. 2016

RSC Adv.

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“…To ensure stabilization of polymer particles, a large amount of colloidal stabilizers such as poly( N ‐vinylpyrrolidone) were usually required . To overcome the use of the steric stabilizers, now there is a trend to employ a macromolecular RAFT (macro‐RAFT) agent instead of a small RAFT agent in the dispersion RAFT polymerization . Besides the advantage of no‐need of stabilizers, the macro‐RAFT agent‐mediated dispersion polymerization affords the one‐pot synthesis of concentrated block copolymer nanoobjects through polymerization‐inducted self‐assembly, which is much beyond the micellization of amphiphilic block copolymer in the block‐selective solvent …”

Section: Introductionmentioning

confidence: 99%

“…Similar to the general dispersion polymerization, the macro‐RAFT agent‐mediated dispersion polymerization generally includes an initial homogeneous RAFT polymerization and a subsequent heterogeneous one . In the initial homogeneous stage, the RAFT polymerization runs much slower than that in the later heterogeneous stage, and a disgustingly long induction time is usually observed especially in the RAFT polymerization of inactive monomers such as styrene .…”

Section: Introductionmentioning

confidence: 99%

“…It is found that the induction time is generally depended on the structure of the RAFT agent (the R or Z group), the chain length and concentration of the macro‐RAFT agent, the solvent character, and the solid content . Compared with the general dispersion polymerization, the induction time in the macro‐RAFT agent‐mediated dispersion polymerization is much longer, and the reason is due to the solvophilic block originated from the macro‐RAFT agent increasing the solubility of the synthesized amphiphilic block copolymer in the solvent and therefore retarding the nucleation of the block copolymer. This induction time prolongs the RAFT polymerization and sometimes even leads to the RAFT polymerization out of control by the RAFT agent .…”

Section: Introductionmentioning

confidence: 99%

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Thermoresponsive diblock copolymer micellar macro-RAFT agent-mediated dispersion RAFT polymerization and synthesis of temperature-sensitive ABC triblock copolymer nanoparticles

Gao

Cui

et al. 2014

J. Polym. Sci. Part A: Polym. Chem.

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The micellar macro-RAFT agent-mediated dispersion polymerization of styrene in the methanol/water mixture is performed and synthesis of temperature-sensitive ABC triblock copolymer nanoparticles is investigated. The thermoresponsive diblock copolymer of poly(N,N-dimethylacrylamide)block-poly[N-(4-vinylbenzyl)-N,N-diethylamine] trithiocarbonate forms micelles in the polymerization solvent at the polymerization temperature and, therefore, the dispersion RAFT polymerization undergoes as similarly as seeded dispersion polymerization with accelerated polymerization rate. With the progress of the RAFT polymerization, the molecular weight of the synthesized triblock copolymer of poly(N,N-dimethylacrylamide)-block-poly[N-(4-vinylbenzyl)-N,N-diethylamine]-b-polystyrene linearly increases with the monomer conversion, and the PDI values of the triblock copolymers are below 1.2. The disper-sion RAFT polymerization affords the in situ synthesis of the triblock copolymer nanoparticles, and the mean diameter of the triblock copolymer nanoparticles increases with the polymerization degree of the polystyrene block. The triblock copolymer nanoparticles contain a central thermoresponsive poly [N-(4-vinylbenzyl)-N,N-diethylamine] block, and the soluble-toinsoluble phase-transition temperature is dependent on the methanol content in the methanol/water mixture.

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“…Narrow‐disperse PNIPAM and PDMA structures are synthesized via RAFT using a phthalimido‐containing CTA . The RAFT polymerization of NIPAM has been already well described as PNIPAM possesses a cloud point temperature of 32 °C, which makes it useful in many biomedical applications . After aminolysis, the phthalimido group was hydrolyzed into a primary amine, yielding polymers with a primary amine at the α‐chain end and a free thiol at the ω‐chain end.…”

Section: Introductionmentioning

confidence: 99%

Straightforward RAFT Procedure for the Synthesis of Heterotelechelic Poly(acrylamide)s

Wallyn

Zhang

Driessen

et al. 2013

Macromol. Rapid Commun.

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Heterotelechelic, hydrophilic polymers with a primary amine and thiol group at the α- and ω-chain end, respectively, are synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization in a straightforward and versatile way and subsequently used for the design of dual-responsive polymer/gold nanohybrids. Therefore, a phthalimido-containing chain transfer agent (CTA) is synthesized and used for the polymerization of the hydrophilic monomers N-isopropylacrylamide (NIPAM) and N,N-dimethylacrylamide (DMA). After polymerization, the trithiocarbonate functionality at the ω-chain end, originating from the CTA, is converted into a thiol upon aminolysis. In the next step, the phthalimido α-chain end is hydrolyzed into a primary amine, resulting in heterotelechelic, hydrophilic polymers. End-group conversions are monitored by (1)H NMR spectroscopy, MALDI-TOF MS analysis, and UV-Vis spectroscopy, confirming that quantitative modifications are obtained during each stage. The amino groups of these heterotelechelic polymer chains are modified with citraconic anhydride, after which the obtained polymers are grafted with the thiol group onto citrate-stabilized gold nanoparticles resulting in the creation of dual-temperature- and pH-responsive gold particles.

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

Cited by 17 publications

References 60 publications

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Thermoresponsive diblock copolymer micellar macro-RAFT agent-mediated dispersion RAFT polymerization and synthesis of temperature-sensitive ABC triblock copolymer nanoparticles

Straightforward RAFT Procedure for the Synthesis of Heterotelechelic Poly(acrylamide)s

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