Microstructure and Physical Properties of a pH-Responsive Gel Based on a Novel Biocompatible ABA-Type Triblock Copolymer

Castelletto, Valeria; Hamley, Ian W.; Ma, Yinghua; Bories-Azeau, Xavier; Armes, Steven P.; Lewis, Andrew L.

doi:10.1021/la049859a

Cited by 66 publications

(63 citation statements)

References 16 publications

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“…However, the gelation behavior turned out to be very complex, due to the double responsive nature of both blocks. Thus, we decided to replace 76 the outer block of the (A n B m ) x star block copolymers with a polymer that is responsive to temperature only.…”

Section: Introductionmentioning

confidence: 99%

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Smart hydrogels based on responsive star-block copolymers

Schmalz

Müller

2012

Soft Matter

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Section: Introductionmentioning

confidence: 99%

“…This is due to the less hydrophobic character of the PDEA chains compared to the PDPA chains. 76,77 Hydrogels based on (AB) x star-shaped block copolymers. There is also a number of reports for star-shaped block copolymers as gelators.…”

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confidence: 99%

Smart hydrogels based on responsive star-block copolymers

Schmalz

Müller

2012

Soft Matter

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“…This open association with an increasing number of bridges can ultimately lead to gelation. [37] In addition to the synthesis of the different conjugates, an in-depth study is performed on the pH-dependent properties of the biotinylated and non-biotinylated triblock copolymers. The evaluation will include dynamic light scattering (DLS), transmission electron microscopy (TEM), and zeta potential and fluorescence spectroscopy measurements.…”

Section: Introductionmentioning

confidence: 99%

pH‐Responsive Flower‐Type Micelles Formed by a Biotinylated Poly(2‐vinylpyridine)‐block‐poly(ethylene oxide)‐block‐poly(ε‐caprolactone) Triblock Copolymer

Butsele

Cajot

Vlierberghe

et al. 2009

Adv Funct Materials

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In the present work, a method is proposed to assemble pH‐responsive, flower‐like micelles that can expose a targeting unit at their periphery upon a decrease in pH. The micelles are composed of a novel biotinylated triblock copolymer of poly(εε‐caprolactone)‐block‐poly(ethylene oxide)‐block‐poly(2‐vinylpyridine) (PCL‐b‐PEO‐b‐P2VP) and the non‐biotinylated analogue. The block copolymers are synthesized by sequential anionic and ring‐opening polymerization. The pH‐dependent micellization behaviour in aqueous solution of the triblock copolymers developed is studied using dynamic light scattering, zeta potential, transmission electron microscopy (TEM), and fluorimetric measurements. The shielding of the biotin at neutral pH and their availability at the micelle surface upon protonation is established by TEM and surface plasmon resonance with avidin and streptavidin‐coated gold surfaces. The preliminary stealthy behavior of these pH‐responsive micelles is examined using the complement activation (CH50) test.

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“…The G' values are very high, being from 5 to 100 times higher than the modulus of recently reported micellar gels. [8,22,23,30,31] In order to give credit to this mechanism, SANS scattering cross sections were recorded at neutral and decreasing pH values (Figure 2). [32] Fairly wide peaks are discerned at neutral pH (soft gel).…”

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confidence: 99%

Fast Multiresponsive Micellar Gels from a Smart ABC Triblock Copolymer

et al. 2007

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Self-assembly of block copolymers in a solvent selective for one block is at the origin of unique behaviors of micellar particles, such as stimuli responsiveness. [1][2][3][4] ABC triblock copolymers are very versatile precursors of micelles, whose internal structure is dictated by the constitutive blocks and their sequential arrangement. Accordingly, smart materials can be contemplated, including multiresponsive ones. Herein, we report on pH-and temperature-sensitive gels formed by an amphiphilic ABC triblock copolymer, polystyrene-bpoly(2-vinylpyridine)-b-poly(ethylene oxide). The selfassembly of this copolymer into core-shell-corona (CSC) micelles [5,6] is observed in N,N-dimethylformamide upon addition of water. The micellar solution forms a soft gel at a lower threshold copolymer concentration (8 wt %) than other systems. [7][8][9] This soft gel is reversibly converted into an optically clear hard gel by merely decreasing the pH value or increasing the temperature. The ordered packing of the CSC micelles and the fast response to pH value were investigated by small-angle neutron scattering (SANS) and rheological measurements.Block copolymers consist of two or more chemically different polymer chains covalently bonded at their chain ends to form one single linear macromolecule.[10] The freeenergy-driven micellization of these copolymers takes place in a selective solvent, that is, a nonsolvent for one block and a good solvent for another. This self-association phenomenon is based on the phase separation of the insoluble blocks, which is, however, restricted to the nanometric scale by a surrounding shell of soluble blocks. Depending on the nature, length, and number of constitutive blocks and their interaction with the solvent, a variety of nanoobjects can be formed in dilute solutions, ranging from typical core-shell nanospheres [11][12][13] to cylinders, [12,14] vesicles, [12,15,16] and tubules, [16] as well as multilayered (onion), [5,17] non-centrosymmetric ("Janus"), and segregated structures. [18,19] Quite importantly, although less extensively studied, higher levels of organization can be observed, that is, assembly into clusters, networks, and gels. Stimulus-triggered aggregation of micelles has been reported for ABA triblock copolymers in a solvent selective for the B block, [9,[20][21][22][23][24] with special attention paid to the well-known polyoxyalkylene-type ABA copolymers (mainly Pluronics). [9,20,21] Among other responsive systems, Armes and coworkers synthesized biocompatible ABA triblocks, where A is poly(N-isopropylacrylamide) and B is poly(2-methacryloyloxyethyl phosphorylcholine).[24] Because of the thermosensitivity of the outer A blocks, micellization and ultimately gelation occurred above a lower critical solution temperature (LCST) of 37 8C. In recent years, increasing attention was paid to sol-to-gel transitions exhibited by multitalented ABC terpolymers. In addition to the synthesis of several isomers of a triblock terpolymer (ABC, BAC, and ACB) by Patrickios and co-workers that were...

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Microstructure and Physical Properties of a pH-Responsive Gel Based on a Novel Biocompatible ABA-Type Triblock Copolymer

Cited by 66 publications

References 16 publications

Smart hydrogels based on responsive star-block copolymers

Smart hydrogels based on responsive star-block copolymers

pH‐Responsive Flower‐Type Micelles Formed by a Biotinylated Poly(2‐vinylpyridine)‐block‐poly(ethylene oxide)‐block‐poly(ε‐caprolactone) Triblock Copolymer

Fast Multiresponsive Micellar Gels from a Smart ABC Triblock Copolymer

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