Brush Formation in Middle-Adsorbing Triblock Copolymers

Pai-Panandiker, R. S.; Dorgan, John R.; Carlin, Richard T.; Uyanık, Nurseli

doi:10.1021/ma00113a055

Cited by 7 publications

(6 citation statements)

References 4 publications

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“…We have compared this observation with data extracted from adsorption studies of different Pluronic system on polystyrene by Baker and Berg (latex particles) and on hydrophobized silica by Steeg and Gölander . We also used data presented by Pai−Panadiker and co-workers on triblock copoly(styrene−ethylene oxide) adsorbed on silica …”

Section: Rsults and Discussionmentioning

confidence: 99%

Equilibrium and Kinetic Properties of Triblock Copolymers at Hydrophobic Surfaces

Eskilsson

Tiberg

1997

Macromolecules

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The adsorption of a series of (ethylene oxide−tetrahydrofuran−ethylene oxide), EO n /2THF m EO n / 2, triblock copolymers has been studied at the water/hydrophobic silica interface by time-resolved ellipsometry. The copolymers form monolayers with the middle tetrahydrofuran block anchoring at the surface and the ethylene oxide groups either anchoring at the surface or protruding into the aqueous phase. The degree of anchoring of the EO chains depends critically on the surface coverage. The copolymer isotherms are generally rather well described by the conventional Langmuir expression, and the plateau surface area per polymer molecule increases linearly with the molecular weight. However, the plateau thickness exhibits a more complex behavior. At low coverages, the adsorbed layer thickness is small, and both THF and EO chains form trains at the surface. As the surface coverage increases, however, the EO chains are increasingly forced away from the surface, and the mean thickness of the adsorbed layer exhibits a relatively strong linear dependence on the surface excess. At higher coverages, closer to the adsorption plateau, a weaker dependence is observed. The thickness increase is in this latter region due to the increasing steric repulsion between protruding EO chains. Outside the adsorbed layer, we also found support for the existence of a depletion layer. We show further that there are three regimes in the kinetics of adsorption. In the first (low surface coverage), the process is diffusion controlled and the rate is proportional to the concentration difference between the bulk solution and the subsurface located just outside the adsorbed layer. In the second regime (intermediate coverages and adsorption times), the kinetics are governed by the rate of displacement of anchored EO chains by THF chains of adsorbing copolymers. In the third regime (high surface coverages), the adsorption slows down markedly due to the energy barrier caused by presence of the relatively dense brush of adsorbed EO chains. In this regime, the surface excess varies proportionally with log t, which was also observed to be the case during the desorption process.

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Section: Rsults and Discussionmentioning

confidence: 99%

Equilibrium and Kinetic Properties of Triblock Copolymers at Hydrophobic Surfaces

Eskilsson

Tiberg

1997

Macromolecules

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“…5,6 The synthesis methods reported are mostly anionic polymerization processes including coupling reaction and sequential polymerization techniques. In addition, it has been reported that PS-b-PEG may be synthesized by conventional free radical polymerization, using a macroinitiator technique, 7,8 but the copolymer had a broad molecular weight distribution. Recent developments in living free radical polymerization have made it possible to control the polymerization to obtain polymers with predetermined molecular weights, narrow molecular weight distributions, and well-defined compositions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of amphiphilic methoxypoly(ethylene glycol)-polystyrene diblock copolymer by ATRP and NMRP techniques

Abbasian

Bonab

Shoaeifar

et al. 2011

Journal of Elastomers & Plastics

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Amphiphilic block copolymers are used in a variety of applications, for example, as stabilizers for emulsions and dispersions or as compatibilizers in polymer blends. Amphiphilic diblock copolymer composed of methoxypoly(ethylene glycol) and polystyrene (MPEG-b-PS) was synthesized using atom transfer radical polymerization (ATRP) and nitroxide-mediated radical polymerization (NMRP). In order to synthesize MPEG-b-PS diblock copolymer using ATRP, monofunctional MPEG macroinitiator (chloroacetylated MPEG [MPEG-Cl]) was prepared from monohydroxyfunctional poly(ethylene glycol) and initiated end group on the basis of chloroacetyl chloride. ATRP was carried out in bulk using MPEG-Cl as the macroinitiator, copper chloride (CuCl)/2,2 0 -bipyridine (bipy) as the catalyst ([MPEG-Cl]/[CuCl]/[bipy] ¼ 1:1:3), and styrene as the monomer. For preparation of MPEG-b-PS by means of NMRP, firstly, 1-hydroxy-2,2,6,6-tetramethylpiperidine (TEMPO-OH) was obtained by reduction of 2,2,6,6-tetramethyl-piperidinyl-1oxy (TEMPO) with sodium ascorbat. Then, TEMPO-OH was coupled with chloroacetylated MPEG (MPEG-Cl) to yield the macroinitiator MPEG terminated with a TEMPO unit

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“…PS is an important thermoplastic material with excellent transparency, high electrical resistibility, and hydrolytic stability,6 whereas PEG is regarded as the most effective polymer for reducing protein adsorption and denaturation because of its low interfacial energy, nonadhesion properties, and high dynamic motion 7, 8. To realize these applications, considerable efforts have been made to prepare PS–PEG block copolymers with various approaches, such as (1) traditional free‐radical polymerization with a macroinitiator technique,9 (2) living anionic polymerization,10 (3) nitroxide‐mediated radical polymerization,11 (4) atom transfer radical polymerization,12 and (5) condensation reaction. Among these polymerization methods, block copolymers obtained with the traditional free‐radical polymerization method have a broad molecular weight distribution, whereas anionic polymerization has to be carried out under anhydrous conditions, and extensive purification of the monomers, solvents, and initiators is also required, and the choice of monomers is still limited for living radical polymerization (including nitroxide‐mediated radical polymerization and atom transfer radical polymerization).…”

Section: Introductionmentioning

confidence: 99%

Facile method for the synthesis of polystyrene–poly(ethylene glycol) block copolymers

Liu

Gou

Yang

et al. 2010

J of Applied Polymer Sci

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A facile method for synthesis of polystyrene-poly(ethylene glycol) block copolymers under mild conditions, for instance, ambient temperature and atmospheric pressure, by the direct esterification condensation reaction was developed. The block copolymers were characterized with such techniques as Fourier transform infrared spectroscopy, 1 H-NMR, gel permeation chromatography, differential scanning calorimetry, and X-ray diffraction. The results show that block copolymers with a yield of over 80%were successfully synthesized with this facile approach, and the resulting block copolymers exhibited both glass-transition and melting endothermal signals and both amorphous and crystal phases as well; this indicated that the block copolymers had a microphase-separated structure.

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Brush Formation in Middle-Adsorbing Triblock Copolymers

Cited by 7 publications

References 4 publications

Equilibrium and Kinetic Properties of Triblock Copolymers at Hydrophobic Surfaces

Equilibrium and Kinetic Properties of Triblock Copolymers at Hydrophobic Surfaces

Synthesis and characterization of amphiphilic methoxypoly(ethylene glycol)-polystyrene diblock copolymer by ATRP and NMRP techniques

Facile method for the synthesis of polystyrene–poly(ethylene glycol) block copolymers

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