Critical dynamics of a polymer chain in a grafted monolayer

Klushin, Leonid I.; Skvortsov, A.M.

doi:10.1021/ma00007a016

Cited by 70 publications

(74 citation statements)

References 5 publications

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“…where w() is the microscopic mobility, and ␤ ϭ 2/3 for free-draining chains or ␤ ϭ 1 when hydrodynamic interactions were taken into account (12). Molecular dynamics and Monte Carlo simulations (20-22) were consistent with the scaling prediction of Eq.…”

supporting

confidence: 55%

“…The active catalyst appears to be heterogeneous and adsorbed on the insoluble K 2 CO 3 (12). Besides its role as a solid support, the carbonate also acts as a base (13), initiating the addition of the alcohol, or DBADH 2 , or both to the copper complex, and as a water scavenger (14).…”

Section: ϫ2mentioning

confidence: 99%

“…Most theoretical and experimental studies (3-10) have addressed the static structure of brushes, such as the density profile above the surface. Although theoretical predictions have been made of their dynamical structure as well (4,5,11,12), direct relevant experimental observation, although much needed (7), is difficult because of the small size of the brush and its low scattering power.We have addressed this problem by performing evanescent-wave dynamic lightscattering (EWDLS) measurements of asymmetric poly(ethyleneoxide-b-styrene) (PEO-PS) copolymers (Fig. 1).…”

mentioning

confidence: 99%

“…Most theoretical and experimental studies (3)(4)(5)(6)(7)(8)(9)(10) have addressed the static structure of brushes, such as the density profile above the surface. Although theoretical predictions have been made of their dynamical structure as well (4,5,11,12), direct relevant experimental observation, although much needed (7), is difficult because of the small size of the brush and its low scattering power.…”

mentioning

confidence: 99%

“…For a grafted brush, the end-to-end chain relaxation was predicted (11,12) to depend on N and on the anchoring density . Considering mean-squared fluctuations of the chain-free end in the perpendicular direction proportional to L 0 2 , a Rouse-like diffusion led to the characteristic q-independent relaxation rate:…”

mentioning

confidence: 99%

See 4 more Smart Citations

Probing Collective Motions of Terminally Anchored Polymers

Fytas

Anastasiadis

Seghrouchni

et al. 1996

Science

115

128

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Polymer chains attached by one end to an impenetrable surface at high coverage exemplify a tethered layer of mesoscopic dimensions. At equilibrium, thermal fluctuations of the segment density profile of the brushlike layer reflect the tethered chain dynamics; the probing of these fluctuations by evanescent-wave dynamic light scattering is reported. By utilizing a set of terminally attached layers with thicknesses (L 0 ) from 45 to 130 nanometers, it was found that there is a preferred wavelength of order L 0 of these fluctuations with a concurrent slowing down of their thermal decay rate. This technique could open the route for the investigation of the largely unexplored area of polymer surface dynamics.When polymer molecules are selectively attached by one end onto a solid surface at relatively high concentrations, the polymer chains avoid one another by extending away from the surface, forming a "brush" (1, 2). The formation of polymer brushes is of technological importance in colloid stabilization and in modifying bulk surfaces and interfaces for improved adhesion, wetting, and wear properties. Such brushes can be created by synthesizing diblock copolymers, in which one shorter block adsorbs strongly to the surface from a solution and the other longer block extends into the solvent. This stretched configuration of tethered chains is used as a model for a wide variety of confined polymer systems (3). Most theoretical and experimental studies (3-10) have addressed the static structure of brushes, such as the density profile above the surface. Although theoretical predictions have been made of their dynamical structure as well (4,5,11,12), direct relevant experimental observation, although much needed (7), is difficult because of the small size of the brush and its low scattering power.We have addressed this problem by performing evanescent-wave dynamic lightscattering (EWDLS) measurements of asymmetric poly(ethyleneoxide-b-styrene) (PEO-PS) copolymers (Fig. 1). Light is reflected from a high-refractive index prism; the polymer is attached at the glass surface at the base of the prism, and the evanescent wave propagates through the polymer brush under conditions of total internal reflection. The evanescent wave is then used as the incident beam in photon correlation spectroscopy (13), which allows fluctuations with wave vector q to be resolved on time scales from 10 Ϫ7 to 10 3 s. From these measurements, we obtained the time-correlation functions C(q, t) of the scatteredlight intensity that reflect concentration fluctuations in the brush. Our results show that long-lived fluctuations have a finite wavelength of order L 0 [O(L 0 )], where L 0 is the equilibrium thickness of the grafted PS layer. This result resembles that for the interal relaxation mode seen in bulk diblock copolymer solutions (14).Detailed material and surface characterization is essential for the interpretation of the results. The PEO-PS model system in toluene was selected on account of the extensive information on adsorbed amount, kinetics of...

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supporting

confidence: 55%

Section: ϫ2mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Probing Collective Motions of Terminally Anchored Polymers

Fytas

Anastasiadis

Seghrouchni

et al. 1996

Science

115

128

View full text Add to dashboard Cite

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Polymer Brushes on Flat and Curved Substrates: What Can be Learned from Molecular Dynamics Simulations

Binder

Егоров

Milchev

2017

Polymer and Biopolymer Brushes

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Formation of entanglements at brushlike interfaces in cellulose–polymer composites

Felix¹,

Gatenholm²

1993

J of Applied Polymer Sci

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SYNOPSISCellulose fibers were grafted with compatibilizing agents, such as maleated polypropylenes of different molecular weights. Steric effects and surface free-energy effects were found to stimulate the stretching of grafted chains away from the cellulose fiber surface, giving rise to a brushlike configuration in a polypropylene ( P P ) melt. Inverse gas chromatography measurements on modified fibers using a model compound for PP as adsorbate showed that interactions of PP and grafted fibers, which were mainly diffusion-dependent, increased with increasing molecular weight of the compatibilizer. Dynamic mechanical measurements and tensile testing of composites showed that the presence of compatibilizing agents enhanced stress transfer and increased interphase thickness considerably, the most significant effect being obtained for the high molecular weight compatibilizers. Apparently, the longer the grafted chains, the larger the fraction of matrix molecules involved in the interactions and, thus, the thicker the interphase. The improvement of adhesion between treated fibers and PP, as detected by peel testing, was proven to be caused mainly by entanglements formed between compatibilizing agents and PP.

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Critical dynamics of a polymer chain in a grafted monolayer

Cited by 70 publications

References 5 publications

Probing Collective Motions of Terminally Anchored Polymers

Probing Collective Motions of Terminally Anchored Polymers

Polymer Brushes on Flat and Curved Substrates: What Can be Learned from Molecular Dynamics Simulations

Formation of entanglements at brushlike interfaces in cellulose–polymer composites

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