Neutron Reflectivity Study of the Density Profile of a Model End-Grafted Polymer Brush: Influence of Solvent Quality

Karim, Alamgir; Satija, Sushil K.; Douglas, Jack F.; Ankner, John F.; Fetters, Lewis J.

doi:10.1103/physrevlett.73.3407

Cited by 201 publications

(283 citation statements)

References 25 publications

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“…28,45,46,47 However, the segment density profiles of the looped brushes studied here in the good solvent toluene (Figure 5a-f) clearly show that these density profiles differ significantly from singly bound brushes: A parabolic function (eq 1) fits only a portion of these density profiles, and a long exponential tail is needed to model the density profile of these brushes. For the brushes in cyclohexane (20,32, and 50°C), as shown in Figure 6, the segment density is also significantly different from that of the singly bound chains, since the density decays more rapidly as the brush extends away from the grafting surface, with no parabolic contribution. These density profiles can be described with an exponential decay, as shown in Figure 6 for D136K.…”

Section: Resultsmentioning

confidence: 93%

“…32 In toluene the parabolic region of the SLD profile is much narrower, and the extended exponential decay tail contributes more significantly to the profile than the profile of singly bound brushes. In cyclohexane, a parabolic region near the surface is not evident, and a long exponential decay dominates the profile.…”

Section: Resultsmentioning

confidence: 99%

“…The shape of the density profiles provides insight into the structure of the looped brushes, as was shown by previous work that examined the structure of singly bound PS brushes in toluene and cyclohexane. 32 In that work, it was found that the majority of the density profile can be fit with a parabolic function, as shown in eq 1. Previous studies of brushes formed from triblock copolymers have indicated that they behave as brushes that are formed from diblock copolymers that are half the length of the triblock.…”

Section: Resultsmentioning

confidence: 99%

“…For instance, Karim et al 32 studied the structure of a chemically bound polystyrene brush in d-toluene, a good solvent for PS, and in d-cyclohexane, whose quality can be controlled by changing temperature. These studies show that the segment density profile is well-described by a parabolic function:…”

Section: Introductionmentioning

confidence: 99%

“…Several theoretical 29,30 and experimental [31][32][33] investigations have examined the structure of singly tethered, linear polymer brushes. For instance, Karim et al 32 studied the structure of a chemically bound polystyrene brush in d-toluene, a good solvent for PS, and in d-cyclohexane, whose quality can be controlled by changing temperature.…”

Section: Introductionmentioning

confidence: 99%

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Impact of Solvent Quality on the Density Profiles of Looped Triblock Copolymer Brushes by Neutron Reflectivity Measurements

et al. 2008

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Preferential adsorption of poly(2-vinylpyridine)-deuterated polystyrene-poly(2-vinylpyridine) (PVP-dPS-PVP) triblock copolymers from toluene onto silicon leads to the formation of dPS loops tethered by the PVP end blocks. Using neutron reflectometry, we have determined the segment density profiles of these looped polymer brushes in toluene, a good solvent for the dPS block, and in cyclohexane at 20°C (poor solvent), 32°C, (near-Θ solvent), and 50°C (marginal solvent). While the swelling behavior qualitatively agrees with that observed for singly grafted brushes, there are interesting differences in the local structural details: In a good solvent, the segment density profiles are composed of an inner parabolic region and a long, extended tail. In cyclohexane, the profiles are described by exponential decays. We ascribe these features to a novel polydispersity effect that arises due to tethering the PS loops by both ends. The results also show that the less dense layers undergo more significant changes in swollen height as solvent quality is changed and that the looped brushes of different molecular weight, asymmetry, and tethering density adhere to scaling relationships derived for lightly cross-linked polymer gels.

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Section: Resultsmentioning

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of Solvent Quality on the Density Profiles of Looped Triblock Copolymer Brushes by Neutron Reflectivity Measurements

et al. 2008

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Adsorption

Rao¹,

Dhinojwala²

2003

Encyclopedia of Polymer Science and Technology

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Polymer adsorption finds widespread applications in the stabilization of colloids, food processing, paints, lubrication, and surface modification. In the past two decades there have been numerous studies aimed at improving our understanding of this important phenomenon. This article reviews the instrumental and theoretical advances made in this area and presents important experimental results concerning adsorbed polymers.

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Polymer Brushes

Hadjesfandiari

Bajgai

et al. 2013

Encyclopedia of Polymer Science and Technology

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Polymer brushes are monolayers of one‐end tethered polymer chains at high graft density on a surface. Owing to the steric interactions between the tethered polymer chains within the brush regime, this class of polymer thin films has unique properties compared to the conventional polymer thin films. Polymer brushes provide an elegant route for surface modification owing to their excellent mechanical stability as well as functional versatility. Among the polymer brush synthesis methods, surface‐initiated polymerization (SIP) offers a unique opportunity for the generation of high graft density polymer brushes. Combined with controlled/living polymerization, the SIP method revolutionized the polymer brush synthesis and allowed the tailoring of surface properties of these molecular thin films. The control of surface properties provided new ways to change wettability, lubrication, and the interaction of biological macromolecules/cells to surfaces and created new opportunities in the design of responsive surfaces, smart materials, biocompatible surfaces, and various biotechnology and nanotechnology applications. This field is rapidly emerging with wide range of applications in multiple research fields and is promoting cross‐disciplinary research.

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Neutron Reflectivity Study of the Density Profile of a Model End-Grafted Polymer Brush: Influence of Solvent Quality

Abstract: Neutron reflectivity measurements are made on a chemically end-grafted polymer brush swollen over

Cited by 201 publications

References 25 publications

Impact of Solvent Quality on the Density Profiles of Looped Triblock Copolymer Brushes by Neutron Reflectivity Measurements

Impact of Solvent Quality on the Density Profiles of Looped Triblock Copolymer Brushes by Neutron Reflectivity Measurements

Adsorption

Polymer Brushes

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