Probing Nanoscale Polymer Interactions by Forced‐Assembly

Liu, Richard Y. F.; Jin, Yuliang; Hiltner, A.; Baer, E.

doi:10.1002/marc.200300051

Cited by 114 publications

(138 citation statements)

References 18 publications

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“…In addition, these results indicate that multilayer films with layer thicknesses at or near the nanoscale [63][64][65] and nanostructured or quasi-nanostructured polymer blends with substantial interfacial area [66][67][68] have the potential for properties that are strongly modified from those expected on the basis of the behavior of bulk, neat polymer or thin films of individual polymers. Bilayer and multilayer experiments employing fluorescence dyes in one layer provide a particularly sensitive method for characterizing novel behavior associated with nanostructured multilayer films and nanostructured blends, and further studies are underway.…”

Section: Ellison and Torkelson Indicating The Large Negative Values Ofmentioning

confidence: 87%

Eliminating the Enhanced Mobility at the Free Surface of Polystyrene: Fluorescence Studies of the Glass Transition Temperature in Thin Bilayer Films of Immiscible Polymers

et al. 2007

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By selective placement of fluorescent dyes, we have measured the glass transition temperature (T g ) of individual layers within supported bilayer films of different polymers to determine the extent to which strong free-surface effects and substrate interactions are mediated by a narrow interface between immiscible polymers. We have discovered that the impact a free surface has on T g within an ultrathin PS layer is extremely sensitive to the polymer species used in the underlayer. The large T g reduction of ∼32 K relative to bulk T g observed for a 14 nm thick surface layer of polystyrene (PS) supported on bulk PS is virtually eliminated when a 14 nm thick surface layer of PS is placed on an underlayer of poly(methyl methacrylate) or poly(2-vinylpyridine) (P2VP), even of bulk thickness. Thus, the cooperative segmental mobility associated with the T g of the PS freesurface layer is greatly hindered by the narrow, several-nanometer-wide interfacial region formed with the dissimilar polymer underlayer. This indicates that the dynamics of nanoscale layers can be strongly modified by adjacent layers or domains of unlike polymers via propagation of effects across an interfacial layer of cooperatively rearranging regions containing segments of the two immiscible polymers, which has important implications for multilayer films and nanostructured blends. Conversely, the T g of an ultrathin P2VP film is unaffected by the presence of a PS capping layer, indicating that strong attractive interactions of P2VP with hydroxyl groups on the surface of the silica substrate dominate over a much weaker free-surface effect in P2VP.

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Section: Ellison and Torkelson Indicating The Large Negative Values Ofmentioning

confidence: 87%

Eliminating the Enhanced Mobility at the Free Surface of Polystyrene: Fluorescence Studies of the Glass Transition Temperature in Thin Bilayer Films of Immiscible Polymers

et al. 2007

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“…74,75 The scientifically and technologically important interphase between two immiscible polymers is probed with assemblies of thousands of alternating layers of two glassy polymers, with the individual layer thickness on the nanometer size scale of the interphase. 76,77 By sensing the composite nature of the assembly, gas transport becomes a primary method for extracting the dimension and other fundamental characteristics of the interphase. Nanolayer assemblies of crystalline polymers are also fabricated by layer-multiplying coextrusion.…”

Section: New Opportunities For Gas Transport As a Structure Probementioning

confidence: 99%

Oxygen transport as a solid‐state structure probe for polymeric materials: A review

Hiltner

Liu

et al. 2005

J Polym Sci B Polym Phys

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ABSTRACT:In the quest to elucidate the solid-state structures of polymers, insight into the amorphous phase is particularly elusive. Although the permeability of small molecules is often measured as an important performance property, numerous researchers have found that a deeper analysis of the transport characteristics provides insight into polymer morphology, especially if used in combination with more usual characterization techniques. The transport of small gas molecules senses the permeable amorphous structure and probes the nature of the free volume. In recent years, our interest in the gas barrier of polyesters has resulted in an unusual opportunity to investigate the nature of the free volume in the polymer glassy state. This effort has been aided by access to aromatic polyesters with designed variations in their chemical structure. This review focuses on oxygen transport, supplemented with other methods of physical analysis, as a probe of the excess-hole free volume. The review addresses the profound effects of orientation and crystallization on the free volume of the glassy state. The discussion also presents a simple odel for the gas permeability of the isotropic glass based on lattice concepts and tests more sophisticated models for the gas permeability of semicrystalline polymers. The final section addresses other opportunities for fruitful applications of oxygen transport as a solid-state structure probe.

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“…In pioneering work, Baer and coworkers have used this "forced assembly" technique and have shown that immiscible polymer pairs and filled/unfilled polymers can be forced to combine into a unique multilayer structure, accompanied with interesting confined crystallization effects [19], gas barrier properties [20], and optical properties [21]. In addition, Koets et al report the toughening of immiscible amorphous polymer pairs by multilayer coextrusion [22].…”

Section: Introductionmentioning

confidence: 99%

Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites

McKenna

Miquelard‐Garnier

et al. 2014

Polymer

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. t r a c tA potential advantage of platelet-like nanofillers as nanocomposite reinforcements is the possibility of achieving two-dimensional stiffening through planar orientation of the platelets. The ability to achieve improved properties through in-plane orientation of the platelets is a challenge and, here, we present the first results of using forced assembly to orient graphene nanoplatelets in poly(methyl methacrylate)/ polystyrene (PMMA/PS) and PMMA/PMMA multilayer films produced through multilayer coextrusion. The films exhibited a multilayer structure made of alternating layers of polymer and polymer containing graphene as evidenced by electron microscopy. Significant single layer reinforcement of 118% at a concentration of 2 wt % graphene was achieveddhigher than previously reported reinforcement for randomly dispersed graphene. The large reinforcement is attributed to the planar orientation of the graphene in the individual polymer layers. Anisotropy of the stiffening was also observed and attributed to imperfect planar orientation of the graphene lateral to the extrusion flow. Ó

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Probing Nanoscale Polymer Interactions by Forced‐Assembly

Cited by 114 publications

References 18 publications

Eliminating the Enhanced Mobility at the Free Surface of Polystyrene: Fluorescence Studies of the Glass Transition Temperature in Thin Bilayer Films of Immiscible Polymers

Eliminating the Enhanced Mobility at the Free Surface of Polystyrene: Fluorescence Studies of the Glass Transition Temperature in Thin Bilayer Films of Immiscible Polymers

Oxygen transport as a solid‐state structure probe for polymeric materials: A review

Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites

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