Small-Angle X-ray and Neutron Scattering from Bulk and Oriented Triblock Copolymer Gels

Mischenko, N; Reynders, K.; Koch, Marta; Mortensen, K.; Pedersen, Jan Skov; Fontaine, F.; Graulus, R; Reynaers, Harry

doi:10.1021/ma00110a045

Cited by 69 publications

(96 citation statements)

References 5 publications

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“…3). Besides the existence of the most disordered state which can be found for every gel series and corresponds to 18-20% in the case of G1651 (Mischenko et al, 1995) and the general tendency for increased order when moving away from this concentration, there are some specific features around the 12% concentration. This concentration seems to correspond to the most ordered gel, whereas different concentrations, even very close to 12%, already give gels that have scattering patterns exhibiting much broader interference maxima.…”

Section: Influence Of the Polymer Concentrationmentioning

confidence: 91%

“…They have high elasticity and deformability (100-1000%, depending on the molar mass and block ratio of the copolymer). These materials are also interesting from the structural point of view, because the rather ordered arrangement of the network nodes results in a morphology intermediate between liquid-like and crystalline types (Mischenko et al, 1995;Lorenzen, 1995;Reynders, 1996). Ordered structures have also been observed in micellar triblock copolymer solutions (Mortensen, Brown & Norden, 1992;Mortensen, Schwahn & Janssen, 1993;Raspaud, Laires, Adam & Carton, 1996), although they do not have elastic rubber properties.…”

Section: Introductionmentioning

confidence: 99%

“…Two models were found useful to describe the morphology of triblock copolymer gels: (i) a liquid of effective (fictitious) hard spheres surrounding the PS domains and (ii) a local coordination model or highly distorted lattice of close-packed spheres (CPS's) (Mischenko et al, 1994(Mischenko et al, , 1995Lorenzen, 1995). The latter model refers to either hexagonal close-packed (HCP) or face-centered cubic (FCC) distorted morphologies.…”

Section: Introductionmentioning

confidence: 99%

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Ordering Phenomena in ABA Triblock Copolymer Gels

Reynders¹,

Mischenko²,

Kleppinger³

et al. 1997

J Appl Cryst

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Temperature and concentration dependencies of the degree of order in ABA triblock copolymer gels are discussed. Two factors can influence the ordering phenomena: the conformation of the midblocks (links of the network) and the polydispersity of the endblock domains (nodes of the network). The latter is defined by the scattering density profile (polymer chain packing) at the domain boundary: a sharp boundary corresponds to less polydisperse domains and to increased order in the arrangement of the network nodes. The structure of the network can be described in terms of a highly distorted crystalline lattice with close-packed spheres or with cubic (presumably BCC) equilibrium morphology. The appearance of the latter is never detected in the gels with a stretched conformation of the midblock.

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Section: Influence Of the Polymer Concentrationmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ordering Phenomena in ABA Triblock Copolymer Gels

Reynders¹,

Mischenko²,

Kleppinger³

et al. 1997

J Appl Cryst

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“…1 (curve A) shows a typical SAXS diffraction pattern for a neat PS-PEB-PS triblock copolymer gel. As extensively discussed elsewhere [21][22][23], the plot of I(q) as a function of q is dominated by the polystyrene micellar cores, and contains information on the corresponding structure factor and the form factor, respectively. The polystyrene form factor peaks, which result from intradomain interferences contain information on the size and shape of the polystyrene domains, whereas the structure factor peaks, which originate from the interdomain interference, provide information on the mutual arrangement of the polystyrene domains within the rubbery matrix.…”

Section: Combined Mechanical and Small-angle Neutron Scattering Expermentioning

confidence: 99%

“…The midblocks form either loops or bridges between micelles, depending on whether the polymer endblocks are located in the same nanophase or not. Two models were found to be useful to describe the scattering patterns of the triblock copolymer gels: a hard sphere liquid model (Percus-Yevick model) or a local co-ordination model [22][23]. The first model represents a liquid of effective hard-sphere cores surrounded by a (fictitious) hard-sphere shell.…”

Section: Introductionmentioning

confidence: 99%

Silica reinforced triblock copolymer gels

Theunissen

Overbergh

Reynaers

et al. 2004

Polymer

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The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to evaluate the influence of the compatibility between gel and filler.Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a viscoelastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel.

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