Effect of chain length on the micellization and gelation of block copoly(oxyethylene/oxybutylene/oxyethylene) EmBnEm

Nicholas, Christian V.; Luo, Yun‐Zhu; Deng, Nanjie; Attwood, David; Collett, John; Price, Colin; Booth, Colin

doi:10.1016/0032-3861(93)90296-m

Cited by 50 publications

(36 citation statements)

References 33 publications

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“…In terms of TRGs, when increasing the MM of the polymer, normally the gelation temperature (T gel ) [37][38][39][40][41][42] and/or the concentration that the gel is obtained at (critical gelation concentration, CGC) 37,38 is decreased. The earliest systematic study where it was observed that both the T gel and CGC decreased when increasing the MM was carried out by Vadnere et al in 1984 on Pluronics® with MMs ranging from 8500 to 13000 g mol -1 .…”

Section: Effect Of Molar Massmentioning

confidence: 99%

“…38 Other studies on ABA triblock copolymers of different chemical structures than Pluronics®, specifically based on ethylene oxide (EO, blocks A) and butylene oxide (BO, block B) instead of propylene oxide (PO) with MM ranging from 6400 to 15500 g mol -1 found that T gel as well as CGC decreased by increasing the MM. 37 In another study, three pairs of random copolymers based on (i) N-isopropyl acrylamide (NIPAAm) and acrylic acid (AA), (ii) NIPAAm and 2-(dimethylamino)ethyl acrylate (DMAEA) and (iii) NIPAAm and 2-carboxyethyl acrylate (DAA) of different MMs (ranging from 300 to 500 kg mol -1 ), were synthesised via free radical polymerisation. 39 Similarly, it was demonstrated that by increasing the MM the T gel decreased.…”

Section: Effect Of Molar Massmentioning

confidence: 99%

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Tuning the gelation of thermoresponsive gels

Constantinou

Georgiou

2016

European Polymer Journal

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Thermoresponsive gels are exciting polymeric materials with many biomedical applications in medical devices, drug delivery, tissue engineering and bio-printing. Also, they have great potential to be used in 3-D printing and thus in the fabrication of many different devices and materials. As it is crucial for the application of these gels to be able to control and tailor the gelation temperature and concentration this was the main focus and point of discussion of this feature article. Thus, it is discussed in detail how by varying the molar mass, composition, stereochemistry and architecture the thermoresponsive properties of these gels are altered.

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Section: Effect Of Molar Massmentioning

confidence: 99%

Section: Effect Of Molar Massmentioning

confidence: 99%

Tuning the gelation of thermoresponsive gels

Constantinou

Georgiou

2016

European Polymer Journal

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“…10 For PEO-PBO-PEO triblock copolymers, where poly(butylene oxide) (PBO) is introduced as the hydrophobic middle block, replacing the PPO block of Pluronics, a similar phase diagram has been observed in concentrated aqueous solutions. 11,12 Therefore, it is suggested that the structure of block copolymers demanded for such phase transition is not confined to PEO and PPO or to PEO and PBO if the balance between hydrophilicity and hydrophobicity in block copolymers is moderately adjusted. In recent reports, studies on thermoreversible gel-sol transition have been expanded to structurally varied block copolymer systems including PEO-aliphatic polyesters.…”

Section: Introductionmentioning

confidence: 99%

Phase-transition characteristics of amphiphilic poly(2-ethyl-2-oxazoline)/poly(?-caprolactone) block copolymers in aqueous solutions

Kim

Lee

Kang

et al. 2000

J. Polym. Sci. B Polym. Phys.

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“…Recently, considerable research has been pergle chains. Also, it was found that neutralized samples that formed on nonionic block copolymers that micellize in aquewe, recovered by freeze-drying and redissolved had a larger ous media (6)(7)(8)(9)(10)(11)(12) or in organic solvents (13)(14)(15)(16)(17). Research on aggregation number V) and R,, than those that were formed the micellization of ionic block copolymers, as compared to directly upon neutralization (25).…”

Section: Introductionmentioning

confidence: 98%

Effect of the degree of neutralization on the micellization of block ionomers

Khougaz¹,

Nguyen²,

Eisenberg³

et al. 1995

Can. J. Chem.

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Abstract:The effect of neutralization on the micellization of polystyrene-b-poly(acry1ic acid) (PS-b-PAA) was investigated by static light scattering (SLS) and small-angle X-ray scattering (SAXS). The block copolymers, present initially in single chain form in either dioxane or benzene-methanol (90110 (vlv)), were neutralized to different degrees by the addition of cesium hydroxide dissolved in methanol. The solutions were simultaneously monitored by SLS. It was found that micelle formation began near 5% neutralization. The normalized scattered light intensity at 90' (19dc) increased dramatically in the neutralization range between ca. 10 and 60%. For neutralization degrees between 60 and ca. loo%, 19dc did not change significantly with a further increase in the percent of neutralization. In the second part of the study, two block copolymers, PS(600)-b-PAA(34) and PS(600)-b-PAA(45) (the number of monomer units is given in parentheses), were prepared from benzenemethanol (90110 (vlv)) with different degrees of neutralization: 5, 25, 60, 100, and 150%. The resulting solutions were freeze-dried and the dried samples were redissolved in toluene. These samples were investigated by SLS and SAXS. By SLS, the aggregation numbers (fl were found to be the same between 5 and 60% neutralization. An increase in f was observed in going from 60 to 100%; i.e., f increased from 82 to 92 for PS(600)-b-PAA(34), and from 79 to 110 for PS(600)-b-PAA(45). The f values for the two block copolymers at 150% neutralization were found to be the same as those for 100% neutralization. The core radii values (R,,,) were measured for the neutralized PS(600)-b-PAA(45) samples at 0.05 g1mL in toluene by SAXS. The R,,,, values increased from 5 to 60% neutralization, remained constant from 60 to loo%, and increased again in the range from 100 to 150%. The results are explained by dynamic considerations. For low percent neutralization, between 5 and 60%, the micelles and single chains are proposed to be in a dynamic equilibrium state. For higher percent neutralization, between 60 and 10070, the dynamics are probably much slower.Key words: block copolymers, micelles, ionomers, light scattering, small angle X-ray scattering (or SAXS).RCsume : Faisant appel A la diffusion statique de la lumitre (SLS) et la diffusion des rayons X A petit angle (SAXS), on a Ctudit l'effet de la neutralisation sur la micellisation du polystyrtne-b-poly(acide acrylique) (PSb-PAA). Les copolymtres A blocs, qui sont prisents initialement sous la forme d'une chaine simple dans le dioxane ou dans un melange benztne-mtthanol(90110 (vlv)), se neutralisent A des degrts divers par l'addition d'hydroxyde de ctsium dissous dans le mCthanol. On a examink les solutions simultaniment par SLS. On a trouvt que la formation de micelles commence prts d'environ 5% de neutralisation. L'intensitC.normalisCe de la lumitre diffuste A 90 ' (19dc) This paper is dedicated to Professor J.E. (Jim) Guillet in recognition of his contributions to Canadian chemistry.

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Effect of chain length on the micellization and gelation of block copoly(oxyethylene/oxybutylene/oxyethylene) EmBnEm

Cited by 50 publications

References 33 publications

Tuning the gelation of thermoresponsive gels

Tuning the gelation of thermoresponsive gels

Phase-transition characteristics of amphiphilic poly(2-ethyl-2-oxazoline)/poly(?-caprolactone) block copolymers in aqueous solutions

Effect of the degree of neutralization on the micellization of block ionomers

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