Interphase control in poly(styrene-block-butadiene-block-styrene) copolymer/magnesium hydroxide composites

Dumitru, Paul; Lees, Graham C.; Liauw, Christopher M.; Rothon, Roger

doi:10.1002/1521-3900(200106)170:1<213::aid-masy213>3.0.co;2-e

Cited by 5 publications

(5 citation statements)

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“…Many researchers have pursued nanocomposites based on either intercalated or exfoliated clay dispersed into various matrix polymers. − However, to date, there has not been a report of an exfoliated nanocomposite structure within a block copolymer matrix. − Forming an exfoliated clay nanocomposite is a challenge due to the unfavorable interactions between the intrinsically hydrophilic clay and the hydrophobic matrix polymer chains. − Thus, methods of organically functionalizing the surfaces of the clay, utilizing the inherent negative surface charges on the clay layers, have been successfully developed. , …”

Section: Introductionmentioning

confidence: 99%

An Orientationally Ordered Hierarchical Exfoliated Clay−Block Copolymer Nanocomposite

Kwon

Breiner

et al. 2005

Macromolecules

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Creation of an orientationally ordered hierarchical nanocomposite can be done by the preferential insertion of individual polymer-covered clay layers into block copolymer (BCP) microdomainsin the present instance, PS-functionalized silicate layers into the polystyrene (PS) domains of a styrene−butadiene−styrene triblock copolymer (SBS). We present here the method required to achieve such an ordered block copolymer−nanoparticle composite and report preliminary mechanical properties. PS is grafted-to or polymerized-from individual clay sheets in order to provide a neutral enthalpic interaction between the PS chains on the clay layers and the PS blocks in the SBS. The molecular weight of the PS chains tethered to the clay was varied, and we show that higher molecular weight is critical in obtaining individual clay sheets dispersed in the SBS matrix. When exfoliated, the clay sheets serve as a template for the lamellar domains. Because of their large areal dimensions and concentration, the clay particles likely form a discotic nematic that is responsible for the observed orientational flipping transition of the BCP layers during the roll-cast process. We also show through experiments and simulations that the mechanical properties of these anisotropic hierarchical nanocomposites are not significantly changed by the insertion of 2 wt % of the clay sheets for deformation parallel to the lamellae.

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Section: Introductionmentioning

confidence: 99%

An Orientationally Ordered Hierarchical Exfoliated Clay−Block Copolymer Nanocomposite

Kwon

Breiner

et al. 2005

Macromolecules

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“…Dumitru et al 29 have studied the effect of adding a very large amount of organically modified clay (60 wt %) in a SBS triblock containing 27.5 wt % styrene. Samples were produced by injection molding.…”

Section: Introductionmentioning

confidence: 99%

Deformation Behavior of a Roll-Cast Layered-Silicate/Lamellar Triblock Copolymer Nanocomposite

Thomas

2002

Macromolecules

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We have produced layered-silicate-lamellar triblock copolymer nanocomposites possessing a uniaxial texture. Solution blending of the layered-silicate suspension with a block copolymer solution and subsequent roll-casting or static casting and annealing resulted in a partially immiscible and intercalated structure with only a low degree of exfoliation. Isotropic polygranular nanocomposite samples prepared by static solution casting exhibit increase in modulus, higher yield stresses, earlier onset of strain hardening, increased strain hardening rate, and higher residual strains upon unloading with increasing layered-silicate content. In-situ and ex-situ deformation studies were performed along various directions on roll-cast nanocomposite samples to elucidate the effects of anisotropic particles upon deformation of the globally textured nanocomposite system. Deformation parallel to the roll-cast direction shows an earlier onset of strain hardening with modest increases in the modulus for particle-loaded films compared to that of the roll-cast neat triblock. The evolution of the triblock copolymer microstructure with applied strain shows the breakup of the glassy polystyrene domains as was found for pure triblock copolymers. Upon unloading, the residual strain increases with increased loading content, and the unloaded SAXS patterns show a distribution of lamellar spacings, suggesting significant unloading effects due to the presence of the clay layers. Deformation perpendicular to the texture axis shows a dramatic increase in the tensile modulus compared to the unreinforced material. The evolution of microstructure with strain in this direction is reminiscent of a neat triblock copolymer where at high strains (∼100%) the layers kink to form the chevron morphology, and the lamellar normals continue to rotate away from the deformation direction with increasing strain at constant lamellar spacing. Unlike a pure triblock copolymer, however, the chevron morphology remains locked in place upon unloading due to the presence of the layered-silicate particles.

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“…As the silicate layers are only about 1 nm thick, the preparation of novel nanostructured polymer materials using microphase-separated block copolymers as the host scaffold and exfoliated clay platelets as the filler presents an interesting challenge . Research on block copolymer/clay nanocomposites has to date been focused on styrene based thermoplastic elastomers. − Blocks in those elastomers generally have relatively low polarity, so inorganic silicate layers usually aggregate and complete exfoliation is difficult to achieve. Several studies have investigated the interaction between clay nanoplatelets and the nanophase structures of the block copolymer.…”

Section: Introductionmentioning

confidence: 99%

Highly Ordered Hierarchical Poly(ethylene oxide)-b-polystyrene/Organoclay Nanocomposites

Zhao

2011

ACS Appl. Mater. Interfaces

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A lamellar forming poly(ethylene oxide)-b-polystyrene (PEO-b-PS)/organoclay nanocomposite with a unique hierarchical structure has been fabricated, by casting solution blends of the block copolymer and organoclay, with subsequent annealing at 180 °C for 8 h under uniaxial constraint. PEO-b-PS provided the nanocomposite lamellar structure with a slightly increased long period. Lamellar layers of the nanocomposite block copolymer were oriented parallel to the film plane. Fully exfoliated clay platelets were localized mostly in the aligned PEO layers, and all platelets were found to be parallel to the interface between PEO and PS layers. PEO crystals in the nanocomposite were oriented with the c-axis perpendicular to the phase-separated layers. The orientation function degree of the PEO crystals within the nanocomposite was lower than that of the crystals within the neat block copolymer.

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Interphase control in poly(styrene-block-butadiene-block-styrene) copolymer/magnesium hydroxide composites

Cited by 5 publications

References 0 publications

An Orientationally Ordered Hierarchical Exfoliated Clay−Block Copolymer Nanocomposite

An Orientationally Ordered Hierarchical Exfoliated Clay−Block Copolymer Nanocomposite

Deformation Behavior of a Roll-Cast Layered-Silicate/Lamellar Triblock Copolymer Nanocomposite

Highly Ordered Hierarchical Poly(ethylene oxide)-b-polystyrene/Organoclay Nanocomposites

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