Tacticity effects on polymer blend miscibility

Beaucage, Greg; Stein, Richard S.; Hashimoto, Takahiro; Hasegawa, Hirokazu

doi:10.1021/ma00011a062

Cited by 50 publications

(53 citation statements)

References 8 publications

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“…As we can see from the wave-vectors at which a maxima in the values of R(q) and I tZ0 are observed, the manifestation of the maximum growth rate in the scattering experiment (I tZ0 ) occurs at a length scale smaller than the maximum growth rate itself. Normally, phase ripening is observed in spinodal decomposition driven by a reduction in surface area [22][23][24] leading to an increase in size for q*. The data shows the opposite of this behavior as q*!q I tZ0 .…”

Section: Spinodal Analysismentioning

confidence: 93%

“…Normally, for linear polymer mixtures at deep thermal quenches, a spinodal-peak is seen to decay to lower-q and to broaden as Ostwald ripening occurs at later stages of phase separation driven by the reduction in free energy of the system through reduction in the surface area of phases [22][23][24]. Surprisingly, in the crosslinked system, phases are not observed to ripen whatsoever (Fig.…”

Section: Vinyl-terminated Systemmentioning

confidence: 96%

“…A 20 mW helium-neon gas laser at 632.8 nm wavelength was used. Using a single pinhole near the sample, the scattering pattern was projected on a screen and imaged with a CCD camera, Princeton Instruments Optical Multichannel Analysizer (OMA) [20][21][22][23]. Background scattering from an identical sample except for the absence of crosslinker was subtracted from the lightscattering patterns.…”

Section: Light Scattering Measurementsmentioning

confidence: 99%

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Reaction induced phase-separation controlled by molecular topology

Kulkarni

Beaucage

2005

Polymer

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Binary phase-separation driven by a difference in branch content of the two components has been widely reported in polyolefins. This concept is applied to polysiloxanes in an attempt to control morphology in chemically driven phase separation. It is shown that selfassembled, non-reversible spinodal morphologies (SD) as well as low-polydispersity nucleation and growth morphologies can be controlled through the rate of network formation in these systems. Time-resolved light scattering and optical microscopy were used to determine the character and kinetics of phase separation. The mechanism of phase separation in two similar systems was dictated by the rates of the crosslinking reactions. Both morphologies were 'locked-in' by network formation and late-stage phase-ripening was prevented by low surface energy associated with topologically driven phase-separation. q

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Section: Spinodal Analysismentioning

confidence: 93%

Section: Vinyl-terminated Systemmentioning

confidence: 96%

Section: Light Scattering Measurementsmentioning

confidence: 99%

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Reaction induced phase-separation controlled by molecular topology

Kulkarni

Beaucage

2005

Polymer

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“…The temporal scaling behavior in the present blend of poly(bromostyrene) and conventional PS is consistent with those reported for other isomeric polymer blends. [2][3][4][5] The blends of PS with high molecular weight Br-PS (M w ϳ100k) and a narrow molecular weight distribution (M w /M n ϳ1.06) that synthesized by anionic polymerization showed complete immiscibility.…”

Section: Effect Of Bromination On Polystyrenementioning

confidence: 99%

“…It is well known that polymer phase diagrams show profound sensitivity not only to molecular weight 1 but also to detailed chemical structures of the constituent polymers. [2][3][4][5][6][7][8] For instance, even a slight modification of a chemical structure of one polymer in a miscible mixture could render the pair immiscible. A notable example includes the influence of tacticity, 2,3 microstructure, 4,5 and/or halogen substitutions on phase diagrams of isomeric polymer blends.…”

Section: Introductionmentioning

confidence: 99%

Effect of aromatic substitution on phase behavior of blends of halogenated polystyrene and conventional polystyrene

Thaweephan

Meng

Sigalov

et al. 2001

J. Polym. Sci. B Polym. Phys.

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Miscibility phase behavior in blends of poly(bromostyrene) with polystyrene (PS) has been investigated by means of time-resolved light scattering, optical microscopy, and DSC. Cloud point phase diagrams of blends of conventional PS with poly-(2-bromostyrene) (P2BrS), poly-(3-bromostyrene), and poly-(4-bromostyrene) of comparable molecular weights were established by light scattering. Of particular interest is the fact that ortho, meta, and para substitutions in the styrenic aromatic rings of poly(bromostyrene) show profound effects on the composition-temperature phase diagrams of their blends with PS, exhibiting a lower critical-solution temperature (LCST), an upper critical solution temperature (UCST), and combined LCST/UCST diagrams, respectively. Poly-(2-chlorostyrene) exhibits an LCST behavior very close to that of the P2BrS blend, suggesting that these types of halogen atoms may be inconsequential to phase behavior. A similar study has been extended to a PS blend containing commercial brominated PS (66 mol % bromine substitution) to determine what location of bromine substitution is crucial for miscibility enhancement in the flameretardant brominated PS blends.

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Tacticity in Vinyl Polymers

Woo

Chang

2011

Encyclopedia of Polymer Science and Technology

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Various issues of tacticity in vinyl polymers are discussed. First, tacticity is defined and the concepts of tactic forms in polymers as a stereoregular configuration order are introduced, and illustration schemes for common polymer tacticity are shown. Effects of tacticity in polymer structures on crystalline morphology and property are briefly discussed. Several commercially useful tactic polymers are examined, by using examples of vinyl‐type polymers such as tactic polypropylene (PP), polystyrene (PS), and poly(methyl methacrylate) (PMMA). Catalysts and synthesis routes for producing stereoregular tactic polymers are discussed mainly using PMMA as an example. Tacticity in polymers is related to differences in microstructures, morphology, crystalline polymorphism, and physical/mechanical properties. Tactic polymers possess structural order and are to crystallize. Tacticity and crystalline properties of polymers are discussed. Crystal polymorphism in some tactic polymers, such as syndiotactic polystyrene (s‐PS), is discussed in greater detail. Complex formation in mixtures of polymers of opposite tacticities, just like mixtures of polymers of opposite chiral forms, has been reported. Complex formation in mixtures of polymers of opposite (s‐ and i‐tacticity) is discussed using examples of isotactic PMMA (i‐PMMA) and syndiotactic PMMA (s‐PMMA); on the other hand, complex formation of mixtures of other tactic polymers, such as i‐PS/s‐PS or i‐PP/s‐PP, is not known. Effects of tacticity on the miscibility and phase behavior in blends of tactic polymers with other polymers are surveyed and expounded. Blends of polymers of same chemical structure but opposite tacticities are not always miscible, as exemplified in a blend of nonpolar and highly crystalline s‐PP with i‐PP, showing immiscibility with upper critical solution temperature behavior but a‐PP being miscible with s‐PP or i‐PP. In addition, phase behaviors of binary blends of two isomeric polymers are addressed. In blends with weak interactions and borderline phase homogeneity, the tacticity effect on miscibility is usually more pronounced; in contrast, the effect on the phase behavior may be minimal in systems with strong intermolecular interactions.

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Tacticity effects on polymer blend miscibility

Cited by 50 publications

References 8 publications

Reaction induced phase-separation controlled by molecular topology

Reaction induced phase-separation controlled by molecular topology

Effect of aromatic substitution on phase behavior of blends of halogenated polystyrene and conventional polystyrene

Tacticity in Vinyl Polymers

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