Temperature-induced ordering and gelation of star micelles based on ABA triblocks synthesized via aqueous RAFT polymerization

Kirkland-York, Stacey E.; Gallow, Keith; Ray, Jacob G.; Loo, Yueh‐Lin; McCormick, Charles L.

doi:10.1039/b823131a

Cited by 16 publications

(23 citation statements)

References 35 publications

(49 reference statements)

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“…ABA triblock copolymers depending on the position of the hydrophobic block A or B can form star‐like or flower‐like micelles. Specifically, if the hydrophobic block is the B block, then the polymers form star‐like micelles, whereas if the A blocks are hydrophobic then the polymer forms flower‐like micelles in water. In the latter, the hydrophobic blocks are in the core of the micelle, whereas the hydrophilic block forms a loop so each polymer chain forms a “petal” and the overall micelle looks like a flower.…”

Section: Introductionmentioning

confidence: 99%

“…In some studies, flower‐like micelles were formed only at higher temperatures because both blocks were hydrophilic in room temperature but the outer blocks were thermoresponsive and at higher temperatures became hydrophobic . In several other studies, mostly by Papadakis and coworkers, the outer blocks are hydrophobic and the middle block thermoresponsive, usually based on N ‐isopropylacrylamide and hence flower‐like micelles are reported at room temperature, whereas in higher concentrations and/or temperatures form physical hydrogels …”

Section: Introductionmentioning

confidence: 99%

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Thermoresponsive gels based on ABA triblock copolymers: Does the asymmetry matter?

Ward

Georgiou

2013

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

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The aim of this study was to investigate the effect of the asymmetry of the triblock copolymers on their thermoresponsive self‐assembly behavior. To this end, nine ABA‐type triblock copolymers with n‐butyl methacrylate and 2‐(dimethylamino)ethyl methacrylate (DMAEMA) consisting of the A and the B blocks, respectively, were synthesized. Polymers of three different DMAEMA contents (50, 60, and 70 wt %) were synthesized while varying the length ratio of the two hydrophobic A blocks. Specifically, one symmetric ABA triblock copolymer and two asymmetric ABA′ triblock copolymers with the length of the second A block to be twice or four times bigger than the length of the first A block (AB2A and AB4A triblock copolymer) were synthesized for each DMAEMA composition. Three statistical copolymers were also synthesized for comparison. The thermoresponsive behavior of the copolymers was studied and it was found that the cloud point and rheological properties of the polymers were strongly affected by the architecture (statistical vs. block) and less strongly by the DMAEMA composition and the asymmetry of the polymers. Nevertheless, interestingly the asymmetry of the ABA triblock copolymers did influence the thermoresponsive behavior with the more symmetric polymers presenting a sol–gel transition at lower temperatures. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2850–2859.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermoresponsive gels based on ABA triblock copolymers: Does the asymmetry matter?

Ward

Georgiou

2013

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

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“…Physically crosslinked hydrogel networks can be prepared by the assembly of RAFT-synthesized triblock copolymers. [86,272,[546][547][548] The structures can be tuned to absorb either hydrophilic or hydrophobic substrates and to swell in specific media or in response to various stimuli such as pH, temperature, ionic strength, etc. by appropriate monomer selection.…”

Section: Polymer Networkmentioning

confidence: 99%

Living Radical Polymerization by the RAFT Process - A Second Update

Moad¹,

Rizzardo²,

Thang³

2009

Aust. J. Chem.

893

720

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This paper provides a second update to the review of reversible deactivation radical polymerization achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379-410). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669-692). This review cites over 500 papers that appeared during the period mid-2006 to mid-2009 covering various aspects of RAFT polymerization ranging from reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses and a diverse range of applications. Significant developments have occurred, particularly in the areas of novel RAFT agents, techniques for end-group removal and transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

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“…40,41 It is also possible to create various polymer architectures such as block and graft copolymers, stars, and nanostructures using RAFT polymerization. 42,43,[44][45][46][47][48][49][50][51] RAFT polymerization offers a highly versatile platform for controlled synthesis and molecular engineering of polymer bioconjugates. [13][14][15][16]25 The strength of the RAFT approach for generation of polymer bioconjugates lies in its ability to control the polymerization of a wide range of monomers in varying solvents including water, at moderate temperatures, using only chain transfer agents and common free radical initiators (without the need for any additional polymerization component such as metal catalysts and sacrificial initiators).…”

Section: Reversible Addition Fragmentation Chain Transfer (Raft) Polymentioning

confidence: 99%

“…In a study aimed to develop a gene carrier, 154 methacrylamide monomers of a DNA condensing peptide (K-12) and an endosomal escape peptide (K6H5) were RAFT-copolymerized with N-(2-hydroxypropyl(methacrylamide) (HPMA) under aqueous conditions using ethyl cyanovaleric trithiocarbonate as a RAFT agent and VA-044 as an initiator in acetate buffer (pH 5.1) at 44 C for 48 h. An important note is that the peptides used in polymerizations were deprotected. An acetic acid buffer at pH 5.1 with a molar strength of 1 M was used to ensure that 3-amines of L-lysine were fully protonated, thereby protecting the trithiocarbonate from nucleophilic attack.…”

Section: 154mentioning

confidence: 99%