Layer by layer imaging of diblock copolymer films with a scanning electron microscope

Harrison, Christopher; Park, Miri; Chaikin, P. M.; Register, Richard A.; Adamson, Douglas H.; Yao, Nan

doi:10.1016/s0032-3861(97)00613-7

Cited by 88 publications

(130 citation statements)

References 24 publications

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“…[29][30][31][32] PI creates a wetting layer at the air interface, and etching has been used to reveal the sub-surface phase structure. More recently, solvent-annealing and the control of the solvent evaporation rate have been found to create ordered structures in a thin film of a similar diblock copolymer, polystyrene-b-polybutadiene (PS-b-PB).…”

Section: Preparation Of Copolymer Templatesmentioning

confidence: 99%

“…Drawing on the structures reported for PS-b-PLMA films, which was called a hybrid structure, 39 we propose that the PS surface shown here in The PI component has a strong interaction with the Si substrate and a lower surface free energy compared with the PS component. 29 Therefore, we expect that in thicker films the PI will wet the Si substrate and also create a wetting layer at the free surface to minimize the total interfacial free energy when in an equilibrium state.…”

Section: Preparation Of Copolymer Templatesmentioning

confidence: 99%

“…To the best of our knowledge, there are no previous studies of the effects of confinement on the non-equilibrium (freshly-cast) structures of PS-b-PI films, as previous work has concerned the equilibrium structures obtained after thermal annealing. [29][30][31] The results in Fig. 1 and Fig.…”

Section: Preparation Of Copolymer Templatesmentioning

confidence: 99%

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Protein Nanopatterning on Self-Organized Poly(styrene-b-isoprene) Thin Film Templates

2009

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Abstract:Templated surfaces can be used to create patterns of proteins for applications in cell biology, bio-sensors and tissue engineering. A diblock copolymer template, which contains a pair of hydrophobic blocks, has been developed. The template is created from well-ordered, non-equilibrium surface structures of poly(styrene-b-isoprene) (PS-b-PI) diblock copolymers, which are achieved in ultrathin films having a thickness less than one domain period. Adsorption and nanopatterning of bovine serum albumin (BSA) on these thin films were studied. After incubation of the copolymer templates in BSA solutions (500 µg/ml) for a period of one hour, BSA molecules formed either a striped or a dense, ring-like structure, closely resembling the underlying polymer templates. In this "hard-soft" PS-b-PI system, BSA molecules were preferentially adsorbed on the hard PS domains, rather than on the soft PI domains. SIMS and contact angle analysis revealed that with more PI localized at the free surface, fewer BSA molecules were adsorbed. SIMS analysis confirmed that BSA molecules were adsorbed selectively on the PS blocks. This is the first example of two hydrophobic blocks of a diblock copolymer being used as a protein patterning template. Previously reported diblock copolymer templates used hydrophilic and hydrophobic pairs. A potentially useful characteristic of this template is that it is effective at high protein solution concentrations (up to 1 mg/ml) and for long incubation times (up to two hours), which broadens its range of applicability in various uses.

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Section: Preparation Of Copolymer Templatesmentioning

confidence: 99%

Section: Preparation Of Copolymer Templatesmentioning

confidence: 99%

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Protein Nanopatterning on Self-Organized Poly(styrene-b-isoprene) Thin Film Templates

2009

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“…The process involves shearing a film of sphere-forming BCP that is two layers thick, and produces alignment over the full extent of the sheared region; the top layer can subsequently be removed by reactive-ion etching with a non-selective gas such as CF 4 , as demonstrated in earlier work. [17] An attractive feature of the technique resides in its simplicity, requiring no specialized laboratory equipment. A two-layer-thick film of a polystyrene±block±poly(ethylene-alt-propylene) (PS±PEP) diblock copolymer was spincoated onto a polished Si substrate; an unpatterned elastomer pad was then placed between an aluminum block and the film.…”

mentioning

confidence: 99%

Shear‐Induced Alignment in Thin Films of Spherical Nanodomains

et al. 2005

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Nanofabrication is witnessing a rapid trend towards using self-assembled templates as a cost-effective method of generating densely patterned surfaces. In particular, templating with block copolymer (BCP) thin films, until recently an area of essentially academic interest, has become increasingly popular in the semiconductor industry. BCPs are macromolecules composed of two (a ªdiblock copolymerº, diBCP) or more chemically distinct, covalently connected, polymer chains, which are typically immiscible in bulk. Molecular connectivity prohibits macroscopic phase separation; instead, BCPs ªmi-crophase separateº, forming nanoscale domains. In diBCPs where one block is much shorter than the other, the minority blocks self-assemble into spheres within a matrix of the majority block; if the length disparity is less pronounced, the nanodomains are cylindrical or lamellar.[1] The self-assembled polymeric patterns obtained in this fashion can be used as templates for lithography. [2] This economical and versatile patterning technique, capable of creating arrays of dielectric, [3] metallic, [4] quantum, [5] or magnetic [6,7] dots spaced only a few tens of nanometers apart, is fully compatible with silicon semiconductor processing [8] and is being applied to the fabrication of devices including magnetic hard drives [9] and, very recently, nanocrystal flash memories.[10] The Achilles' heel of this fabrication technique is lack of addressability, which limits data storage density to well below the theoretical maximum of one bit per dot. While the arrays typically display excellent short-range order, only limited long-range order can be achieved by traditional self-assembly because of the existence of topological defects. Recent research efforts have been directed at guiding the self-assembly process to induce long-range in-plane order in the array of BCP nanodomains that define the templated structures. The high degree of isotropy imposed by the hexagonal packing of the spherical nanodomains complicates the alignment problem: electric fields, although highly successful for in-plane alignment of cylinder-forming BCPs, [11] which define the templates for stripe arrays, have not been profitably applied to arrays of BCP spheres. Good alignment, however, can be achieved by using straight, microfabricated substrate features (mesas [12] or troughs [13,14] ) to impose a preferential lattice orientation (graphoepitaxy). While the alignment persists everywhere along such a straight feature, it extends for at most a few micrometers in the direction normal to the feature. The degree of alignment obtained by graphoepitaxy can be significantly improved by increasing the mobility of the polymer chains via thermal or solvent [15] annealing, yet these methods are (by themselves) ineffective in imposing a predefined lattice direction. We demonstrate below that a previously developed shearing technique, [16] when applied to thin films of sphereforming BCPs, results in BCP dot-array templates with excellent long-range order. The process involves s...

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“…While methods employing progressive (layer-by-layer) etching in conjunction with either surface probe microscopy [3] or field-emission scanning electron microscopy [4] have been introduced for this intention, TEMT has provided the most detailed 3D analysis of nanostructured polymers and polymer nanocomposites to date. The present work will provide a timely overview of TEMT in the investigation of various "soft" materials possessing nanoscale morphological features.…”

mentioning

confidence: 99%

Transmission Electron Microtomography (TEMT) of Nanostructured Polymers and Polymer Nanocomposites

Spontak

Gozen

Braunfeld

et al. 2005

MAM

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Numerous emerging nanotechnologies exploit the morphological characteristics and/or properties of nanostructured polymers or polymers into which inorganic species are either chemically grown or physically dispersed. Microphase-ordered block copolymers, macromolecules capable of spontaneously self-organizing into a variety of periodic and nonperiodic morphologies possessing a characteristic length scale typically on the order of tens of nanometers, constitute excellent examples of nanostructured polymers under consideration for nanotechnological purposes [1]. Hybrid organic/inorganic materials composed of a polymer and nanoscale objects (particles, plates, rods and tubes) with at least one characteristic length scale measuring on the order of a few to tens of nanometers are commonly referred to as nanocomposites and have received considerable attention due to their unique, and sometimes unexpected, properties [2].The spatial characteristics of nanostructured polymers and polymer nanocomposites are crucial in dictating the ultimate thermal, mechanical, optical and transport properties of such advanced materials and must be fully characterized in 3D to understand their role in property development and stability. While methods employing progressive (layer-by-layer) etching in conjunction with either surface probe microscopy [3] or field-emission scanning electron microscopy [4] have been introduced for this intention, TEMT has provided the most detailed 3D analysis of nanostructured polymers and polymer nanocomposites to date. The present work will provide a timely overview of TEMT in the investigation of various "soft" materials possessing nanoscale morphological features.Our previous studies of block copolymer systems self-organizing into periodic [5] and nonperiodic [6] bicontinuous morphologies have demonstrated that the local and global topological characteristics of such morphologies can be fully quantitated from TEMT volume elements reconstructed (by the filtered back-projection technique) from digital image sets with sub-pixel alignment error, thereby yielding unprecedented direct measurement of, for instance, interfacial curvature/area, coordination and genus. As demonstrated earlier [6], the principal advantage of TEMT over other strategies developed to elucidate the 3D characteristics of nanostructured polymers and polymer nanocomposites is its ability to provide quantifiable information with regard to nonperiodic morphologies. The images shown in Fig. 1 have been acquired from a macro/microphase-separated block copolymer/homopolymer blend exhibiting both periodic and nonperiodic channels of the minor component in a matrix of the major component. Topological analysis of these data reveals that the coexisting morphologies only differ in their genus. A single section of the reconstruction of a templated block polymer is displayed with its 3D volume element in Fig. 2. Time-dependent nanostructured polymer morphologies, as well as discrete shapes (such as nanotubes), will also be presented and discussed in th...

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Layer by layer imaging of diblock copolymer films with a scanning electron microscope

Cited by 88 publications

References 24 publications

Protein Nanopatterning on Self-Organized Poly(styrene-b-isoprene) Thin Film Templates

Protein Nanopatterning on Self-Organized Poly(styrene-b-isoprene) Thin Film Templates

Shear‐Induced Alignment in Thin Films of Spherical Nanodomains

Transmission Electron Microtomography (TEMT) of Nanostructured Polymers and Polymer Nanocomposites

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