Influence of hydrophilic and hydrophobic low-molecular-weight additives on the thermoresponsiveness of star-shaped poly-2-isopropyl-2-oxazoline in solution

Amirova, Alina; Kirila, Tatyana; Blokhin, A. N.; Razina, A. B.; Bursian, A. E.; Теньковцев, А. В.; Филиппов, А. П.

doi:10.1016/j.mencom.2020.07.033

Cited by 10 publications

(4 citation statements)

References 14 publications

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“…Comparison of the obtained results with the literature data for other star-shaped pseudo-polypeptoids shows that their behavior in water–salt solutions depends on the core structure. For example, for water–salt solutions of eight-arm star-shaped poly-2-isopropyl-2-oxazoline with calix [ 8 ] arene core (at polymer concentration c = 0.0050 g⋅cm −3 ), the dependence of the phase separation temperature on the N-PTS content was monotonic [ 70 ], and the decrease in T 1 in the c salt range from 0–0.06 M was about 4 °C. Note that for the CPh6-PiPrOx studied in this work, the Δ T 1 value exceeded 20 °C.…”

Section: Resultsmentioning

confidence: 99%

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Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

et al. 2021

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The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

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Section: Resultsmentioning

confidence: 99%

“…N -PTS can be considered as a model for cetylpyridinium chloride known for its antimicrobial and antifungal effects. N -PTS influences the self-organization in solution of thermoresponsive polymers [ 70 ], because both N -methyl pyridinium cation and tosylate anion affect the hydrogen bond network of water [ 71 , 72 , 73 , 74 ].…”

Section: Introductionmentioning

confidence: 99%

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

et al. 2021

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“…This approach was used by Kobayashi et al who were the first to report the preparation of tetra-armed poly(2-methyl-2-oxazolines) and poly(2-ethyl-2-oxazolines) . Since then, this method has been applied to prepare star poly(2-R-2-oxazolines) (R = methyl, ethyl, and isopropyl) with cores varying in shape and structural complexity, such as polycyclic derivatives, − calixarenes, − silsesquioxanes, , carbosilane dendrimers, pentaerythrityl and other polyalkyl derivatives, − cyclotriphosphazenes, porphyrins, ,, cyclodextrins, hyperbranched structures, and perbromomethyl-2-oxazoline …”

Section: Introductionmentioning

confidence: 99%

High-Sensitivity Microcalorimetry and Gel Permeation Chromatography in Tandem Reveal the Complexity of the Synthesis of Poly-(2-isopropyl-2-oxazoline) Stars

2021

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A series of star poly(2-isopropyl-2-oxazolines) (S-PIPOZ) was prepared by two different approaches: “coupling-onto (CO)” and “core-first (CF)”. On the one hand, for “the core-first” approach, SCF-PIPOZ were prepared by direct cationic ring opening polymerization from a tetra tosylate-functionalized pentaerythrityl core. On the other hand, for the “coupling-onto” approach, SCO-PIPOZ were synthesized by coupling via copper alkyne-azide cycloaddition between L-PIPOZ-N3 and a tetrafunctionalized alkyne core. Taking advantage of the thermosensitive properties of PIPOZ, high-sensitivity microcalorimetry analyses (HS-DSC), in addition to commonly used 1H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and spectrophotometry (UV analyses), proved to be powerful tools. On the one side, microcalorimetry analysis facilitates purification of the polymers by setting the appropriate temperature for centrifugal fractionation, and on the other side, it helps in the resolution of their microstructures. SCO-PIPOZ demonstrated good correlation between the 1H NMR, GPC, and UV results and showed sharp unimodal HS-DSC endotherms. Contrary to the SCO-PIPOZ data, SCF-PIPOZ results revealed a discrepancy between the molecular weights measured by 1H NMR and GPC. This issue was resolved with the help of HS-DSC, which allowed detection of different populations of polymers to analyze them before and after isolation by isothermal centrifugal fractionation. Cleavage of the arms of the isolated SCF-PIPOZ showed incomplete/not uniform synthesis of S-PIPOZ by the “core-first” approach. These results highlight the importance of HS-DSC coupled with the commonly used analytical techniques for both refinement and elucidation of the microstructure of architecturally complex thermosensitive polymers such as star polymers.

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“…They provide powerful tools for the synthesis of polymers with specifi ed molecular weight (MW), chemical structure, and architecture including dendrimers, hyperbranched polymers, multiple-arm stars, molecular brushes, and other macromolecular structures. [1][2][3][4][5][6][7][8] Among these CRP methods, SFRP, or the synthesis of polymers mediated by stable nitroxide radicals in the reversible inhibition regime, is one of the best studied approaches that does not require additional purifi cation of polymers from catalysts. 9-11 Stable nitroxide radicals and alkoxyamines (ААs) used as main SFRP agents are often synthesized from commercially available spin traps.…”

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confidence: 99%

Structural and hydrodynamic characteristics of polystyrene synthesized in the presence of conjugated dinitrones

et al. 2021

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A series of branched high-molecular-weight alkoxyamines (HAAs) based on polystyrene of diff erent molecular weight were synthesized using nitroxide radicals generated in situ in the presence of conjugated dinitrones (N,N-dimethylglyoxaldinitrone, N,N-di-tert-butylglyoxaldinitrone, and N,N-diphenylglyoxaldinitrone). Structural features of the products obtained were studied by MALDI-TOF mass spectrometry. Modifi cation of the synthesized HAAs in the presence of azobisisobutyronitrile, carbon tetrabromide, dodecyl mercaptane, 4,5,5-trimethyl-2,2-diethyl-2,5-dihydroimidazole-1-oxyl, and 3,5-di-tert-butylbenzoquinone, as well as thermolysis of the HAAs in the presence of atmospheric oxygen showed that the nitroxide fragments are located within the polymer chain irrespective of the initial structure of the conjugated dinitrone. The molecular weight characteristics and conformational properties of the nitroxidecontaining linear macromolecules and polymers were studied by static and dynamic light scattering and by viscometry. In most cases, the calculated values of the ρ-parameter (R g /R h ) and the Zimm viscosity factor of the branched polystyrene samples synthesized using conjugated dinitrones are lower than those of linear analogues.

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Influence of hydrophilic and hydrophobic low-molecular-weight additives on the thermoresponsiveness of star-shaped poly-2-isopropyl-2-oxazoline in solution

Cited by 10 publications

References 14 publications

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

High-Sensitivity Microcalorimetry and Gel Permeation Chromatography in Tandem Reveal the Complexity of the Synthesis of Poly-(2-isopropyl-2-oxazoline) Stars

Structural and hydrodynamic characteristics of polystyrene synthesized in the presence of conjugated dinitrones

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