Zigzag Morphology of a Poly(styrene-b-hexyl isocyanate) Rod-Coil Block Copolymer

Chen, J. T.; Thomas, Edwin L.; Ober, Christopher K.; Hwang, Seung Sang

doi:10.1021/ma00109a048

Cited by 224 publications

(193 citation statements)

References 14 publications

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“…The supramolecular structures of rod-coil polymers arise from a combination of organizing forces including the repulsion of the dissimilar blocks and the packing constraints imposed by the connectivity of the blocks, and the tendency of the rod block to become orientationally ordered. It is not surprising that many unusual symmetries such as zigzag and arrowhead phases have been observed [61,70]. The thin film structure, however, of rod-coil block copolymers is not nearly as well understood or reproducible as that of the coil-coil type blocks discussed elsewhere in this review.…”

Section: Ordering Of Functional Block Copolymersmentioning

confidence: 85%

“…These molecular pairs may be influenced by an enthalpic contribution to x through the effective coordination number which is maximized when both blocks are elongated [60]. Fascinating self-assembled structures observed by Chen et al indicate that the presence of a much stiffer rod block fundamentally affects microphase separation [61]. Many simulations predict that as the stiffness of one of the blocks is significantly increased, a new class of intermolecular interactions is introduced, in particular the display of liquid crystalline phases such as nematic or layered smectic structures with molecules arranged with their long axes nearly parallel to each other [62][63][64][65][66][67][68][69].…”

Section: Ordering Of Functional Block Copolymersmentioning

confidence: 99%

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Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

933

921

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The nanometer-scale architectures in thin films of self-assembling block copolymers have inspired a variety of new applications. For example, the uniformly sized and shaped nanodomains formed in the films have been used for nanolithography, nanoparticle synthesis, and high-density information storage media. Imperative to all of these applications, however, is a high degree of control over orientation of the nanodomains relative to the surface of the film as well as control over order in the plane of the film. Induced fields including electric, shear, and surface fields have been demonstrated to influence orientation. Both heteroepitaxy and graphoepitaxy can induce positional order on the nanodomains in the plane of the film. This article will briefly review a variety of mechanisms for gaining control over block copolymer order as well as many of the applications of these materials. Particular attention is paid to the potential of perfecting long-range two-dimensional order over a broader range of length scales and the extension of these concepts to functional materials and more complex architectures. #

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Section: Ordering Of Functional Block Copolymersmentioning

confidence: 85%

Section: Ordering Of Functional Block Copolymersmentioning

confidence: 99%

Patterning with block copolymer thin films

Segalman

2005

Materials Science and Engineering: R: Reports

933

921

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“…Experimental studies by J. T. Chen et al [24] demonstrated both monolayer and bilayer smectic ordering in rod-coil diblock copolymers consisting of a highly rigid polyhexyl-isocyanate block joined to a flexible polystyrene coil. However, these results were complicated by the simultaneous occurrence of tilted (or smectic-C) ordering and crystallization of the rigid blocks.…”

Section: Introductionmentioning

confidence: 99%

Entropy-induced smectic phases in rod coil copolymers

Düchs¹,

Sullivan²

2002

J. Phys.: Condens. Matter

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We present a self-consistent field theory (SCFT) of semiflexible (wormlike) diblock copolymers, each consisting of a rigid and a flexible part. The segments of the polymers are otherwise identical, in particular with regard to their interactions, which are taken to be of an Onsager excludedvolume type. The theory is developed in a general three-dimensional form, as well as in a simpler one-dimensional version. Using the latter, we demonstrate that the theory predicts the formation of a partial-bilayer smectic-A phase in this system, as shown by profiles of the local density and orientational distribution functions. The phase diagram of the system, which includes the isotropic and nematic phases, is obtained in terms of the mean density and rigid-rod fraction of each molecule. The nematic-smectic transition is found to be second order. Since the smectic phase is induced solely by the difference in the rigidities, the onset of smectic ordering is shown to be an entropic effect and therefore does not have to rely on additional Flory-Huggins-type repulsive interactions between unlike chain segments. These findings are compared with other recent SCFT studies of similar copolymer models and with computer simulations of several molecular models.

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“…Work conducted collaboratively by the Ober (Cornell) and Thomas (MIT) groups has focused on both LC rodamorphous coil block copolymers [19][20][21][22][23] and amorphous side-group LC-amorphous coil block copolymers [6,15,19,20,24], as well as fluorinated side group LC copolymers [25]. The structure of the azobenzene mesogen based stryene-isoprene side-group LC diblock is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

Understanding and controlling the morphology of styrene–isoprene side-group liquid crystalline diblock copolymers

Osuji

Chen

Mao

et al. 2000

Polymer

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In side-chain liquid crystalline diblock copolymers, driving forces for ordering of the material may be provided by the chemical incompatibility between the blocks and by the liquid crystalline nature of one of the blocks. We study the microstructure and its development from initially isotropic solutions in side-group liquid crystalline copolymers based on styrene-isoprene diblocks. Hierarchical structure from the 5 Å to the 500 Å length scale is observed, the product of coherent block copolymer microphase separation and liquid crystalline mesophase formation. The presence of cylindrical microdomains of either the poly(isoprene-LC) or poly(styrene) block markedly increased the thermal stability of the LC. Confinement of the LC to cylindrical microdomains strongly inhibited defect formation within the mesophase after suitable orientation and thermal treatment, readily manifested by the significantly improved optical clarity of these samples versus LC matrix or LC lamellar samples. We consider the relative stabilities of parallel-transverse, perpendicular-parallel, parallel-parallel and transverse-perpendicular arrangements of the microdomain and mesophase structures in interpreting the development of structure in these materials under oscillatory shear. ᭧

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Zigzag Morphology of a Poly(styrene-b-hexyl isocyanate) Rod-Coil Block Copolymer

Cited by 224 publications

References 14 publications

Patterning with block copolymer thin films

Patterning with block copolymer thin films

Entropy-induced smectic phases in rod coil copolymers

Understanding and controlling the morphology of styrene–isoprene side-group liquid crystalline diblock copolymers

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