Synthesis and Self-Assembly of Thermoresponsive PEG-<i>b</i>-PNIPAM-<i>b</i>-PCL ABC Triblock Copolymer through the Combination of Atom Transfer Radical Polymerization, Ring-Opening Polymerization, and Click Chemistry

Chen, Jiucun; Liu, Mingzhu; Gong, Honghong; Huang, Yawen; Chen, Chen

doi:10.1021/jp208494w

Cited by 73 publications

(63 citation statements)

References 49 publications

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“…For the copolymer with the short PEG spacer, increased polymer concentration favor a lower CP value (27 → 21 °C). The drop in cloud point with increasing polymer concentration seems to be a general feature for many thermoresponsive copolymers and homopolymers . The turbidity and cloud point behavior may be rationalized in the following scenario.…”

Section: Resultsmentioning

confidence: 92%

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Khorshid

Zhu

Knudsen

et al. 2016

Macromolecular Bioscience

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The thermoresponsive amphiphilic block copolymer poly(d,l-lactic acid-co-glycolic acid)-block-poly(ethylene glycol)-block-poly(d,l-lactic acid-co-glycolic acid) (PLGA-PEG -PLGA), which exhibits a reversible temperature-induced sol-gel transition at higher polymer concentrations in aqueous solution has attached a great deal of interest because of its potential in biomedical applications. In the present work, the length of the hydrophobic PLGA blocks is kept constant, whereas the length of the hydrophilic PEG block is altered and this variation has a pronounced impact on the phase behavior of the aqueous samples and the structure of the polymer. A short PEG block promotes gelation at a low temperature, whereas a longer PEG block shifts the gelation point to higher temperature. By using a combination of turbidity, rheology, and small angle neutron scattering (SANS) methods, the authors have revealed dramatic temperature effects. In dilute solution, the SANS experiments expose asymmetric ellipsoid structures for the copolymer with the short PEG-spacer, whereas spherical core-shell structure is observed for the polymer with long PEG-spacer. In the semidilute concentration regime, SANS measurements disclose similar profiles for the two copolymers. In a broad temperature interval, the transition from spherical core-shell micelles to cylindrical structure and packing of cylinders is observed.

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Section: Resultsmentioning

confidence: 92%

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Khorshid

Zhu

Knudsen

et al. 2016

Macromolecular Bioscience

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“…8,9 During the past decade, hydrogels which can switch between free-owing liquid and free-standing gel states have attracted much interest. 10 In particular, great attention has been focused on the intelligent ones, which have broadly tunable characteristics, as they can exhibit a sol-gel transition in response to various external stimuli, such as pH, 11 temperature, 12 and ionic strength, 3 magnetic elds, etc.…”

Section: Introductionmentioning

confidence: 99%

Micellization and gelatinization in aqueous media of pH- and thermo-responsive amphiphilic ABC (PMMA₈₂-b-PDMAEMA₁₅₀-b-PNIPAM₆₅) triblock copolymer synthesized by consecutive RAFT polymerization

et al. 2017

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The multi-stimuli-responsive amphiphilic ABC triblock copolymer of poly(methyl methacrylate)-block-poly [N,N-(dimethylamino) ethyl methacrylate]-block-poly(N-isopropylacrylamide) (PMMA-b-PDMAEMA-b-PNIPAM) was synthesized by sequential reversible addition-fragmentation chain transfer (RAFT) polymerizations. Due to the pH-and thermo-responsive blocks of PDMAEMA and thermo-responsive blocks of PNIPAM, the copolymer solution properties can be manipulated by changing the parameters such as temperature and pH, and it formed diverse nanostructures and had gel behavior in different conditions. In detail, when the pH was below 7.3, the pK a of DMAEMA, tertiary amino groups were protonated, the polymer micellar solution like weak gel changed into free-standing gel at around 40 C even at a low concentration of 2 wt%. Further, the gel behavior and morphology of the system were studied by rheology, turbidimetry measurements, transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. When the pH was above the pK a , the triblock copolymer selfassembled into diverse micellar structures including shell-core, corona-shell-core and shell-shell-core nanoparticles as the temperature increased, but no free-standing gelation. The two-step thermoresponsive behavior, corresponding to the different LCSTs of PNIPAM block and DMAEMA block, was evidenced by turbidity analysis. The assembled structures rapidly collapsed due to the enhanced hydrophobic interaction when the temperature further increased. Dynamic light scattering (DLS) was used to confirm the transitions.

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“…At the same time, LCST is a thermodynamic parameter defining the critical temperature at which interchain aggregation starts to occur [25]. Figure 3 shows the transmittance curves versus temperature for triblock copolymer aqueous solutions of PMH1, PMH2 and PMH3 that contain different HMAM contents (Table 1).…”

Section: Temperature Sensitivity Of P(meo 2 Ma-co-hmam) -B-peg-b-p(mementioning

confidence: 99%

Sol–gel transition of novel temperature responsive ABA triblock copolymer P(MEO2MA-co-HMAM)-b-PEG-b-P(MEO2MA-co- HMAM)

Peng

Liu

et al. 2015

J Polym Res

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A well-defined temperature responsive ABA triblock copolymer, poly(2-(2-methoxyethoxy) ethyl methacrylate-co-N-hydroxymethyl acrylamide)-b-poly(ethylene glycol)-b-poly (2-(2-methoxyethoxy) ethyl methacrylate-co-Nhydroxymethyl acrylamide) [P(MEO 2 MA-co-HMAM)-b-PEG-b-P(MEO 2 MA-co-HMAM)], was synthesized by atom transfer radical polymerization (ATRP). The synthesized triblock copolymer was characterized by 1 H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and Gel Permeation Chromatography (GPC). The aqueous solution phase behaviors of the triblock copolymers were investigated by UV transmittance measurements, surface tension measurement, laser particle size and viscosity analysis. The micellization of temperature responsive triblock copolymer was investigated by fluorescence probe technique, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The results showed that the molecular weight of the poly(ethylene glycol) (PEG), the Nhydroxymethylacrylamide (HMAM) content, and the degree of polymerization (DP) of the P(MEO 2 MA-co-HMAM) block for the synthesized triblock copolymers could all affect the lower critical solution temperature (LCST) of the triblock copolymer aqueous solution. The higher the molecular weight of the PEG and the HMAM content for a given triblock copolymer are, the higher the LCST of its aqueous solution. The higher the DP of the P(MEO 2 MA-co-HMAM) block is, the lower the LCST of the copolymer aqueous solution. Sol-gel transition temperature (T sol-gel ) for the triblock copolymer determined by vial inversion test further indicated that it is dependent on the molecular weights of the PEG, the DP of the P(MEO 2 MA-co-HMAM) blocks and the concentration of the copolymer aqueous solution. Copolymer hydrogels loaded with bovine serum albumin (BSA) were used for the release study. The results revealed that 1) the hydrogels had sustained release for the BSA, 2) the release rate for the BSA is dependent of the length of the PEG chain, and 3) the longer the PEG chain is, the faster the release rate of the hydrogel for the BSA.

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Synthesis and Self-Assembly of Thermoresponsive PEG-b-PNIPAM-b-PCL ABC Triblock Copolymer through the Combination of Atom Transfer Radical Polymerization, Ring-Opening Polymerization, and Click Chemistry

Cited by 73 publications

References 49 publications

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Micellization and gelatinization in aqueous media of pH- and thermo-responsive amphiphilic ABC (PMMA₈₂-b-PDMAEMA₁₅₀-b-PNIPAM₆₅) triblock copolymer synthesized by consecutive RAFT polymerization

Sol–gel transition of novel temperature responsive ABA triblock copolymer P(MEO2MA-co-HMAM)-b-PEG-b-P(MEO2MA-co- HMAM)

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Synthesis and Self-Assembly of Thermoresponsive PEG-b-PNIPAM-b-PCL ABC Triblock Copolymer through the Combination of Atom Transfer Radical Polymerization, Ring-Opening Polymerization, and Click Chemistry

Cited by 73 publications

References 49 publications

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Novel Structural Changes during Temperature‐Induced Self‐Assembling and Gelation of PLGA‐PEG‐PLGA Triblock Copolymer in Aqueous Solutions

Micellization and gelatinization in aqueous media of pH- and thermo-responsive amphiphilic ABC (PMMA82-b-PDMAEMA150-b-PNIPAM65) triblock copolymer synthesized by consecutive RAFT polymerization

Sol–gel transition of novel temperature responsive ABA triblock copolymer P(MEO2MA-co-HMAM)-b-PEG-b-P(MEO2MA-co- HMAM)

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Micellization and gelatinization in aqueous media of pH- and thermo-responsive amphiphilic ABC (PMMA₈₂-b-PDMAEMA₁₅₀-b-PNIPAM₆₅) triblock copolymer synthesized by consecutive RAFT polymerization