Effect of unidirectional shear on the structure of triblock copolymers. 2. Polystyrene-polyisoprene-polystyrene

Morrison, Faith A.; Winter, H. Henning; Gronski, W.; Barnes, John

doi:10.1021/ma00221a004

Cited by 68 publications

(58 citation statements)

References 4 publications

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“…Much less attention has been given to the rheological behaviour of triblock copolymers in the lamellar phase. [13][14][15] Studies so far have focused on cylindrical domains [16][17][18][19][20][21][22][23][24] and on triblock copolymer solutions. [25] The main emphasis of our present work is to compare the orientation behaviour and the kinetics between phase separated linear diblock and linear triblock copolymer under LAOS conditions.…”

Section: Full Papermentioning

confidence: 99%

Kinetics of Shear Microphase Orientation and Reorientation in Lamellar Diblock and Triblock Copolymer Melts as Detected via FT‐Rheology and 2D‐SAXS

Oelschlaeger

Gutmann

Wolkenhauer

et al. 2007

Macro Chemistry & Physics

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The microphase orientation/reorientation alignment kinetics behaviour of lamellar PS‐b‐PB diblock and PS‐b‐PB‐b‐PS triblock copolymers under LAOS conditions is studied. By online monitoring the degree of the mechanical nonlinearity during the orientation process, as determined via the higher harmonics in FT rheology [i.e: I3/1(t), ϕ3(t)], and investigation of the orientation distribution by 2D‐SAXS, the kinetics of the microphase alignment for different experimental shear conditions was followed. For di‐ and triblock copolymers, the shear orientation into parallel alignment is possible and the kinetics of orientation is strongly dependent on the strain amplitude.

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Section: Full Papermentioning

confidence: 99%

Kinetics of Shear Microphase Orientation and Reorientation in Lamellar Diblock and Triblock Copolymer Melts as Detected via FT‐Rheology and 2D‐SAXS

Oelschlaeger

Gutmann

Wolkenhauer

et al. 2007

Macro Chemistry & Physics

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“…27 As noted earlier, zero measured birefringence in the 1-3 plane is consistent with parallel alignment, but confirms neither it nor provides a measure of the quality of the orientation state. Using the oblique light path methods described in section 2.3.3, it is possible to characterize the degree of alignment achieved by oscil- a T ) (6.14 × 10 -12 )e 7672/T(K) (7) latory flow at high frequencies. The specialized flow cells for these measurements are, however, limited to room-temperature experiments.…”

Section: Alignment In Oscillatory Shear Flowmentioning

confidence: 99%

Steady and Oscillatory Shear Flow Alignment Dynamics in a Lamellar Diblock Copolymer Solution

Zryd

Burghardt

1998

Macromolecules

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Shear flow alignment in a symmetric polystyrene-polyisoprene (PS-PI) diblock copolymer solution in dioctyl phthalate has been studied using flow birefringence and rheology. In large amplitude oscillatory shear, we find behavior similar to that previously reported in lamellar PS-PI melts. At high reduced frequency, parallel alignment of the layers is preferred, confirmed with birefringence measurements using oblique light paths. At low reduced frequency, perpendicular alignment is favored. In steady shear flow experiments well below the ODT, a similar behavior pattern is found: perpendicular alignment results at low shear rates, and parallel alignment is found at high shear rates. These are the first results demonstrating flipping by a change in steady shear flow conditions. As temperature is increased, the degree of perpendicular alignment obtained at low reduced shear rates decreases, unlike the behavior in large amplitude oscillatory flow, where high degrees of perpendicular alignment are achieved at low frequencies even close to the ODT. This suggests that flow alignment in steady shear is more complex than that in oscillatory shear flow, perhaps owing to an increased likelihood for defect formation. Finally, no flow-induced changes were observed in the order-disorder transition in either steady or large amplitude oscillatory shear flow.

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“…In this case, the effective composition f", associated with the statistical segments of blocks measured along the field is equal: j~"'p N. I -f Keller, Pedemonte, and Willmouth [11], Hadziioannou et al [12), Balsara and Hammouda [13], Rorno-Uribe and Windle [14], and Albalak and Thomas [15] studied the alignment of hexagonally cylindrical and lamellar microdomains in diblock copolymers, solvated diblock copolymers, and random copolymers, respectively, under deformations. Le Meur et al [16]reported on a shift of the order-disorder transition temperature by a shear, and Morrison et al [17] have shown that the degree of phase mixing depends on the strain. Finally, reorientational transitions in dynamically sheared diblock copolymers were recently observed by Koppi et al [18].…”

Section: Reentrant Phase Transitionsmentioning

confidence: 99%

Why Does an Electric Field Align Structures in Copolymers?

Gurovich

1995

Phys. Rev. Lett.

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A microscopic statistical theory of diblock copolymer melts in an electric field is developed within the framework of the random phase approximation.It is found that copolymer melts reveal four different universal types of behavior under an applied field near the spinodal point. The mean-field theory predicts a field-induced shift of both transition temperatures and the spinodal line, the suppression of the body-centered-cubic phase, and the orientational and reorientational phase transitions. New parameters determining the phase behavior have been identified. PACS numbers: 83.70.Hq, 47.20.Hw, 64.70.Md Complex polymeric liquids reveal an extremely strong tendency to segregation. The incompatibility of monomers sequences gives rise to various phase transitions in block copolymers, blends, and binary polymeric solutions. The past few years have seen a renewal of interest in the behavior of these systems under electric fields.Ten years ago Moriya, Adachi, and Kotaka [1] demonstrated that anisotropic structures in blends could be generated by applying an electric field and .uggest ed a new approach for the modulation of polymer blends morphology (see also [2]). The effect of an electric field on diblock copolymer patterns and on the orderdisorder transition temperature was recently discussed by Amundson et al. [3]. They reported on the macroscopic alignment of a lamellar microstructure induced by application of an electric field while cooling through the orderdisorder transition. Small angle x-ray scattering (SAXS) results clearly showed the persistence of the ordered structure even after heating the materials 14 K above the critical temperature given for zero electric field. The electric field-induced remixing for binary polymer solutions at a temperature below the coexistence curve, for the first time, was discussed by Wirtz, Berend, and Fuller [4].In this Letter, we report the basic results [5] of a microscopic theory of microphase separation of diblock copolymers in an applied field near the spinodal point.The analysis will be within the framework of the random phase approximation.The random phase approximation for microphase separation in zero electric field was developed by Leibler [6]. The essential result [6] is that the only parameters on which the phase diagram depends are product gN (~i s the Flory-Huggins effective interaction parameter) and f, the fraction of A statistical segments N~to a full number of statistical segments N~+ N~in a chain. Since the squared gyration radii of blocks [R(")]2 and [R ] are proportional to the numbers of statistical segments N~and

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Effect of unidirectional shear on the structure of triblock copolymers. 2. Polystyrene-polyisoprene-polystyrene

Cited by 68 publications

References 4 publications

Kinetics of Shear Microphase Orientation and Reorientation in Lamellar Diblock and Triblock Copolymer Melts as Detected via FT‐Rheology and 2D‐SAXS

Kinetics of Shear Microphase Orientation and Reorientation in Lamellar Diblock and Triblock Copolymer Melts as Detected via FT‐Rheology and 2D‐SAXS

Steady and Oscillatory Shear Flow Alignment Dynamics in a Lamellar Diblock Copolymer Solution

Why Does an Electric Field Align Structures in Copolymers?

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