Multicenter polyester initiators for the synthesis of graft copolymers with oligo(2-ethyl-2-oxazoline) side chains

Kurlykin, M. P.; Bursian, A. E.; Golub, Olga V.; Филиппов, А. П.; Теньковцев, А. В.

doi:10.1134/s1560090416040059

Cited by 7 publications

(5 citation statements)

References 24 publications

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“…Grafting density z was calculated as z = N 1 /( N 1 + N 2 ) = ( M cop − M b )/ M s ( DP APE ) where N 1 + N 2 = DP APE is the polymerization degree of APE macroinitiator, N 1 and N 2 are respectively the numbers of monomeric units of APE which contain or not contain PiPrOx side chain, M cop is molar mass of APE-g-PiPrOx copolymer ( Figure 1 ), and M b = 19,000 g·mol −1 [ 55 ] is the backbone molar mass. According to calculations, z = 0.49, i.e., one side chain corresponded to two monomeric units of the copolymer.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains

et al. 2020

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New thermoresponsive graft copolymers with an aromatic polyester backbone and poly(2-isopropyl-2-oxazoline) (PiPrOx) side chains are synthesized and characterized by NMR and GPC. The grafting density of side chains is 0.49. The molar masses of the graft-copolymer, its backbone, side chains, and the modeling poly-2-isopropyl-2-oxaziline are 74,000, 19,000, 4300, and 16,600 g·mol−1, respectively. Their conformational properties in nitropropane as well as thermoresponsiveness in aqueous solutions are studied and compared with that of free side chains, i.e., linear PiPrOx with a hydrophobic terminal group. In nitropropane, the graft-copolymer adopts conformation of a 13-arm star with a core of a collapsed main chain and a PiPrOx corona. Similarly, a linear PiPrOx chain protects its bulky terminal group by wrapping around it in a selective solvent. In aqueous solutions at low temperatures, graft copolymers form aggregates due to interaction of hydrophobic backbones, which contrasts to molecular solutions of the model linear PiPrOx. The lower critical solution temperature (LCST) for the graft copolymer is around 20 °C. The phase separation temperatures of the copolymer solution were lower than that of the linear chain counterpart, decreasing with concentration for both polymers.

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Section: Resultsmentioning

confidence: 99%

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains

et al. 2020

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“…This concept has been successfully utilized, for e.g., with poly(methyl methacrylate)- graft -poly(ethylene glycol) (PMMA- g -PEG), to encapsulate anticancer and anti-inflammatory drugs [ 7 , 8 ] or for PEG-grafted polyamides [ 9 ]. Graft copolymers comprising hydrophilic POx side chains have been synthesized via grafting from [ 10 , 11 ], grafting onto [ 12 , 13 ], as well as grafting through methods [ 14 , 15 , 16 ].…”

Section: Introductionmentioning

confidence: 99%

PMMA-g-OEtOx Graft Copolymers: Influence of Grafting Degree and Side Chain Length on the Conformation in Aqueous Solution

et al. 2018

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Depending on the degree of grafting (DG) and the side chain degree of polymerization (DP), graft copolymers may feature properties similar to statistical copolymers or to block copolymers. This issue is approached by studying aqueous solutions of PMMA-g-OEtOx graft copolymers comprising a hydrophobic poly(methyl methacrylate) (PMMA) backbone and hydrophilic oligo(2-ethyl-2-oxazoline) (OEtOx) side chains. The graft copolymers were synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of methyl methacrylate (MMA) and OEtOx-methacrylate macromonomers of varying DP. All aqueous solutions of PMMA-g-OEtOx (9% ≤ DG ≤ 34%; 5 ≤ side chain DP ≤ 24) revealed lower critical solution temperature behavior. The graft copolymer architecture significantly influenced the aggregation behavior, the conformation in aqueous solution and the coil to globule transition, as verified by means of turbidimetry, dynamic light scattering, nuclear magnetic resonance spectroscopy, and analytical ultracentrifugation. The aggregation behavior of graft copolymers with a side chain DP of 5 was significantly affected by small variations of the DG, occasionally forming mesoglobules above the cloud point temperature (Tcp), which was around human body temperature. On the other hand, PMMA-g-OEtOx with elongated side chains assembled into well-defined structures below the Tcp (apparent aggregation number (Nagg = 10)) that were able to solubilize Disperse Orange 3. The thermoresponsive behavior of aqueous solutions thus resembled that of micelles comprising a poly(2-ethyl-2-oxazoline) (PEtOx) shell (Tcp > 60 °C).

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“…For this polymer, the values A ≈ 4-4.7 nm were obtained, which are increased, compared to flexible-chain polymers, due to aromatic fragments in the meta position. Although the comparison of structures of APE O and PMPhIPhA is quite approximate, it can be assumed that the equilibrium rigidity of APE O should not be greater than that of PMPhIPhA, since the -O-spacer present in the structure of APE O allows rotation of the chain around the valence bond; thus, Kuhn segment length for APE O should be 2 nm < A < 4 nm, where A = 2 nm was obtained for APE macroinitiators with flexible alkylene spacers [74]. Then the APE O chain consists of more than 15 Kuhn segments, therefore it should be sufficiently coiled in solution.…”

Section: Molecular and Conformational Properties Of Ape O And Ape O -...mentioning

confidence: 99%

“…The degree of shielding of the molecular brush backbone by side chains and its accessibility for contacts can be quantitatively characterized by the parameter δ that takes into account the size of the side chain folded into a molecular coil [24]. This parameter is conveniently calculated in terms of the number of bonds in the side chains and in the fragments of the main chain between their grafting points, δ = [(N A × N s )] 0.5 /(N 0 × z), where the number of bonds in the Kuhn segment of the side chain N A = 3 for PiPrOx [74], and N 0 × z characterizes the number of bonds in the backbone of the brush between adjacent side chains. Characteristically, the degree of shielding for the studied brushes is always low (Table 2).…”

Section: Molecular and Conformational Properties Of Ape O And Ape O -...mentioning

confidence: 99%

Loose Semirigid Aromatic Polyester Bottle Brushes at Poly(2-isopropyl-2-oxazoline) Side Chains of Various Lengths: Behavior in Solutions and Thermoresponsiveness

et al. 2022

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A polycondensation aromatic polyester with an oxygen spacer was synthesized and used as a macroinitiator for the grafting of linear poly(2-isopropyl-2-oxazoline) (PiPrOx) by the cationic polymerization method. The length of the thermosensitive side chains was varied by the initiator:monomer ratio. Using methods of molecular hydrodynamics, light scattering and turbidimetry, the copolymers were studied in organic solvents and in water. The molecular characteristics of the main chain and graft copolymers, the polymerization degree of side chains and their grafting density have been determined. The equilibrium rigidity of the macroinitiator and the conformations of grafted macromolecules were evaluated. In selective solvents, they take on a star-like conformation or aggregate depending on the degree of shielding of the main chain by side chains. The thermoresponsiveness of graft copolymers in aqueous solutions was studied, and their LCST were estimated. The results are compared with data for graft copolymers composed of PiPrOx side chains and flexible or rigid chain backbones of aromatic polyester type.

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Multicenter polyester initiators for the synthesis of graft copolymers with oligo(2-ethyl-2-oxazoline) side chains

Cited by 7 publications

References 24 publications

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains

PMMA-g-OEtOx Graft Copolymers: Influence of Grafting Degree and Side Chain Length on the Conformation in Aqueous Solution

Loose Semirigid Aromatic Polyester Bottle Brushes at Poly(2-isopropyl-2-oxazoline) Side Chains of Various Lengths: Behavior in Solutions and Thermoresponsiveness

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