Orientation Flip of Lamellar Polystyrene−Polyisoprene Diblock Copolymers under Extrusion

Leist, Heike; Geiger, K.; Wiesner, Ulrich

doi:10.1021/ma981544c

Cited by 30 publications

(39 citation statements)

References 24 publications

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“…[21,22] Wiesner and co-workers have found that a combination of strain and shear frequency determines the orientation process of diblock copolymers. [17] The evolution of microstructural orientation in block copolymers was studied in real time by Kornfield and coworkers using birefringence measurements on diblocks sheared in situ. [18,19] During recent years Ikkala and co-workers have introduced a new concept to prepare functional polymeric materials based on self-assembly of comb-shaped supramolecules.…”

Section: Introductionmentioning

confidence: 99%

Rheology Pathway to Macroscale Ordered Nanostructures of Polymeric Nanotemplates: Nanopores, Nanosheets and Nanofibers

Fahmi

Gutmann

Vogel

et al. 2006

Macro Materials & Eng

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Summary: The creation of nanotemplates under dynamic shear flow conditions is described. The structures used are based on the self‐organization of comb‐coil‐like diblock copolymer systems with two intrinsic length scales, resulting from combining diblock copolymers with hydrogen‐bonding amphiphiles. Rheological data of polymeric supramolecular order formation are studied under oscillating shear flow conditions and it was observed that the order of the polymeric nanodomains can be extended to macroscopic distances. It is proposed that the key success factor to obtain highly ordered samples is to perform the orientation process using appropriate rheological conditions (temperature, frequency and strain) selected such that the ratio of the elastic component G′ to the viscous component G″ is larger than 1. This observation was used to select the rheological parameters for the three different samples investigated, where three different types of nanotemplates are observed after extracting the hydrogen‐bonding amphiphile; nanosheets, hollow cylinders and nanofibres. SAXS is primarily used to inspect the resulting structures. Additionally, AFM and TEM were utilized to image the morphologies and to further act as visual proof for the efficiency of the rheological orientation process.AFM phase image of PS‐b‐P4VP nanosheets on Si wafer substrate after extracting the PDP.magnified imageAFM phase image of PS‐b‐P4VP nanosheets on Si wafer substrate after extracting the PDP.

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Section: Introductionmentioning

confidence: 99%

Rheology Pathway to Macroscale Ordered Nanostructures of Polymeric Nanotemplates: Nanopores, Nanosheets and Nanofibers

Fahmi

Gutmann

Vogel

et al. 2006

Macro Materials & Eng

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“…[21,22] Wiesner and co-workers have found that a combination of strain and shear frequency determines the orientation process of diblock copolymers. [28] Perpendicular orientation has been found at intermediate frequencies, while parallel orientations exist at low and high frequencies. Furthermore, a certain threshold value of strain amplitude needs to be crossed to obtain perpendicular orientation.…”

Section: Introductionmentioning

confidence: 99%

Organisation of Designed Nanofibres Assembled in Filaments via Flow Alignment

Fahmi¹,

Brünig²,

Weidisch³

et al. 2005

Macro Materials & Eng

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Summary: Well‐aligned polymeric nanofibres have been prepared by a simple but effective melt‐spinning procedure. The influence of the extrusion process of a diblock copolymer polystyrene‐block‐poly(4‐vinylpyridine) (PS‐block‐P4VP) hydrogen bonded with surfactant [Ikkala et al., Science 2002, 295, 2407] pentadecylphenol (PDP) on orientation and their structural features have been investigated. Atomic Force Microscopy (AFM) and small angle X‐ray scattering (SAXS) demonstrated that the resulting nanofibres were based on PS cylinders within P4VP(PDP) matrix. The large scale orientation of the PS cylindrical structures were formed by microphase segregation in the melt when low flow rates were applied. The diameter of PS nanofibres in P4VP(PDP) matrix was about 90 nm. After removing the PDP surfactant with suitable solvent, polymeric nanofibres were obtained with diameter of 110 nm. The diblock copolymer nanofibres were formed from a PS core with P4VP shell and were more than 15 μm long. These nanofibres can be produced in large quantities, because extrusion is a continuous process. They can serve as templates for further modifications such as metallization [A. W. Fahmi et al., Adv. Mater. 2003, 15, 1201] or as components for composites with other materials.Topography image and resulting cross section obtained from AFM of PS/PVP nanofibres.imageTopography image and resulting cross section obtained from AFM of PS/PVP nanofibres.

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“…Roll casting has proved to be a reliable method for producing films with long-range order starting from block copolymer solutions [171]. For the case of extrusion, it has been reported that diblock copolymers orient in parallel and perpendicular directions or become disordered, depending on the shear rate and annealing [172,173]. Still more puzzling, the extrusion of pentablock solutions at high shear rates produces a stable transverse orientation [174].…”

Section: Extensional and Other Complex Flowsmentioning

confidence: 99%

Block Copolymers in External Fields: Rheology, Flow‐Induced Phenomena, and Applications

Cloître

Vlassopoulos

2011

Applied Polymer Rheology

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Orientation Flip of Lamellar Polystyrene−Polyisoprene Diblock Copolymers under Extrusion

Cited by 30 publications

References 24 publications

Rheology Pathway to Macroscale Ordered Nanostructures of Polymeric Nanotemplates: Nanopores, Nanosheets and Nanofibers

Rheology Pathway to Macroscale Ordered Nanostructures of Polymeric Nanotemplates: Nanopores, Nanosheets and Nanofibers

Organisation of Designed Nanofibres Assembled in Filaments via Flow Alignment

Block Copolymers in External Fields: Rheology, Flow‐Induced Phenomena, and Applications

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