Concentration Profiles of End-Grafted, Diblock and Triblock Polymers in the Melt: Near-Wall Structure and Effects of Segment-Wall Interaction
TL;DR: In this article, the effect of monomer-wall interactions was investigated by grafting to neutral or attractive interfaces, where bulk-like screening of the excluded-volume interactions for grafted chains is expected to be effective.
Abstract: We report a neutron reflectivity and secondary-ion mass spectrometry study of segment-density profiles of grafted polymers in a homopolymer matrix. The effect of monomer-wall interactions was investigated by grafting to neutral or attractive interfaces. The low-density grafting regime was studied where bulk-like screening of the excluded-volume interactions for grafted chains is expected to be effective. Experiments confirm this picture of screened interactions. Current many-chain calculations do not appear to predict the ideal chain statistics observed for the neutral-wall case, nor reproduce the experimentally observed variation of the profiles with wall interaction strength.
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TL;DR: A review of the current literature on polymer analysis using cluster beams focuses on the surface and in-depth characterization of polymer samples with cluster sources, but will also discuss the characterization of other relevant organic materials, and basic polymer radiation chemistry.
Abstract: Cluster secondary ion mass spectrometry (cluster SIMS) has played a critical role in the characterization of polymeric materials over the last decade, allowing for the ability to obtain spatially resolved surface and in-depth molecular information from many polymer systems. With the advent of new molecular sources such as , , , and , there are considerable increases in secondary ion signal as compared to more conventional atomic beams (Ar+, Cs+, or Ga+). In addition, compositional depth profiling in organic and polymeric systems is now feasible, without the rapid signal decay that is typically observed under atomic bombardment. The premise behind the success of cluster SIMS is that compared to atomic beams, polyatomic beams tend to cause surface-localized damage with rapid sputter removal rates, resulting in a system at equilibrium, where the damage created is rapidly removed before it can accumulate. Though this may be partly true, there are actually much more complex chemistries occurring under polyatomic bombardment of organic and polymeric materials, which need to be considered and discussed to better understand and define the important parameters for successful depth profiling. The following presents a review of the current literature on polymer analysis using cluster beams. This review will focus on the surface and in-depth characterization of polymer samples with cluster sources, but will also discuss the characterization of other relevant organic materials, and basic polymer radiation chemistry. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:247–293, 2010
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Cites background from "Concentration Profiles of End-Graft..."
...There are several examples of polymeric depth profiling with atomic beams including PS (Whitlow & Wool, 1989, 1991; Zhao et al., 1991; Shwarz et al., 1992; Liu et al., 1995; Zheng et al., 1995; Strzhemechny et al., 1997; Rysz et al., 1999; Yokoyama et al., 1999; Shin et al., 2001; Hu et al., 2003; Lin et al., 2003; Harton, Stevie, & Ade, 2006a,b,c; Harton et al., 2006d), PAMA (Valenty et al....
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...…several examples of polymeric depth profiling with atomic beams including PS (Whitlow & Wool, 1989, 1991; Zhao et al., 1991; Shwarz et al., 1992; Liu et al., 1995; Zheng et al., 1995; Strzhemechny et al., 1997; Rysz et al., 1999; Yokoyama et al., 1999; Shin et al., 2001; Hu et al., 2003; Lin et…...
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IBM1
TL;DR: In this paper, a brief review is given on the basic principles of reflectivity, a discussion of some of the areas where reflectivity has made an impact in polymers and a review of a systematic series of studies on block copolymers which serve as an ideal example to emphasize how reflectivity can be used to extract detailed information on a specific problem.
Abstract: Over the last few years reflectivity methods have emerged as key tools for the investigation of polymer surfaces and interfaces. The high spatial resolution of these techniques, of the order of 5 A, has provided a means of probing density gradients in polymers on a submolecular level. This resolution, coupled with selective labeling of all or parts of polymer chains has permitted the examination of polymers at surface and interfaces with unsurpassed detail. Herein, a brief review is given on the basic principles of reflectivity, a discussion of some of the areas where reflectivity has made an impact in polymers and a review of a systematic series of studies on block copolymers which serve as an ideal example to emphasize the strengths of reflectivity and how reflectivity can be used to extract detailed information on a specific problem.
107 citations
TL;DR: In this article, a molecular dynamics simulation of polymeric brushes immersed in a melt of mobile polymer chains is presented, where brush height and monomer density profiles are presented for chains of length N grafted at one end to a solid surface immersed in polymers of the same type.
Abstract: A molecular dynamics simulation of polymeric brushes immersed in a melt of mobile polymer chains is presented. The brush height and monomer density profiles are presented for chains of length N grafted at one end to a solid surface immersed in a melt of polymers of the same type. As the chain length P of the free chains increases there is a crossover from a wet to a dry brush in agreement with scaling and self‐consistent field theories. Since the interaction between all monomers are identical, this crossover is driven purely by entropic interactions. The simulation results are compared to earlier simulations in which the solvent is treated as a continuum. The explicit introduction of solvent molecules increases the equilibration time of the system by a factor of 40–100 even for small P. The dynamics of the brush chains were also studied. The relaxation time for the radius of gyration and end‐to‐end distance was found to be independent of P for small P in agreement with the prediction based on a hydrodynam...
100 citations
TL;DR: In this article, the authors reviewed experimental results on the equilibrium properties of interfaces created by polymer mixtures confined in thin polymers and proposed a mean field model to analyze the properties of these interfaces.
Abstract: Interfaces formed or exposed by polymer mixtures are often employed in modern technological applications. This is especially true for thin polymer films used nowadays in photoresist lithography, electrooptical devices or nanometer-scale surface patterning. Apart from these technology-oriented aspects the interfacial phenomena in thin polymer films pose a fundamental scientific challenge to physics of polymers and thermodynamics of condensed matter. This work reviews experimental results on the equilibrium properties of interfaces created by polymer mixtures confined in thin films. It confronts experimental data with theoretical expectations based mainly on mean field models. Most of the data have been obtained by high resolution profiling techniques emerged in the last decade. These techniques allow us to trace concentration vs depth profiles across a thin film with a depth resolution better than the characteristic size of a polymer coil. The interfacial phenomena of phase coexistence and segregation are described as observed in thin polymer films. This work also considers related issues in the focus of current research such as wetting phenomena, finite size effects expected in very thin films, surface (and bulk) properties of mixtures with stiffness disparity and conformational properties of end-segregated macromolecules forming polymer brushes.
71 citations
TL;DR: In this article, the focused ion beam (FIB) lift-out technique was used to obtain cross-sections that reveal structure near the silicon interface and hence the surface induced phase transitions could be examined and compared quantitatively with theoretical models.
Abstract: Thin poly(styrene210-b-2-vinylpyridine 200) and poly(2-vinylpyridine94-b-styrene760-b-2-vinylpyridine94) films spun cast on silicon and annealed at 1808C for 3 days were directly cross sectioned in less than 1 h using the focused ion beam (FIB) lift-out technique. We show that with the FIB procedure, it is possible to produce cross sections that reveal structure near the silicon interface and hence the surface induced phase transitions could be examined and compared quantitatively with theoretical models. Atomic force microscopy, dynamic secondary ion mass spectrometry, and transmission electron microscopy were used to characterize the films.q 2000 Elsevier Science Ltd. All rights reserved.
49 citations