Interfacial Phenomena in Thin Polymer Films: Phase Coexistence and Segregation

Budkowski, Andrzej

doi:10.1007/3-540-48836-7_1

Cited by 93 publications

(33 citation statements)

References 237 publications

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“…These data were then used to determine the dynamics of the segregation process of a copolymer to the interfacial region with the model of Kramer and Jones. Kramer and Jones37–40 developed this model to describe the kinetics of the growth of the surface excess layer, invoking a model that includes a depletion layer neighboring the surface excess layer. With the copolymer volume fraction profile derived from NR, the copolymer interfacial excess Z * value can be calculated as follows: where Φ c ( z ) and Φ b are the copolymer volume fraction at depth z and the copolymer volume fraction in the bulk, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The growth of such a wetting layer at the free surface of miscible polymer blends has been widely investigated 34–44. Kramer and Jones37–40 considered a local equilibrium between the surface layer and a depletion layer located immediately below the surface layer to describe the surface segregation process. This model predicts the square root of time ( t 1/2 ) kinetics of a polymer wetting layer that saturates after a sufficient annealing time.…”

Section: Introductionmentioning

confidence: 99%

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Using neutron reflectivity to determine the dynamic properties of a copolymer in a homopolymer matrix

Arlen

Dadmun

Hamilton

2004

J Polym Sci B Polym Phys

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A protocol for using neutron reflectivity to monitor the dynamic properties of a copolymer in a homopolymer matrix is described. This technique may be used to monitor a broad range of systems, as long as the copolymer and homopolymer form a miscible blend at low copolymer concentrations. Moreover, with knowledge of the Flory-Huggins interaction parameter between the copolymer and homopolymer, the molecular dynamic parameters of the copolymer, such as the tracer diffusion coefficient, segmental friction factor, and longest relaxation time, can be quantitatively determined. This technique is demonstrated by the determination of these parameters for a series of styrene/methyl methacrylate alternating copolymers dispersed in a matrix of deuterated poly(methyl methacrylate). Interestingly, the segmental friction factor of these alternating copolymers is significantly different from that of similar diblock copolymers.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using neutron reflectivity to determine the dynamic properties of a copolymer in a homopolymer matrix

Arlen

Dadmun

Hamilton

2004

J Polym Sci B Polym Phys

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“…[22][23][24] Phase separation in blends proceeds either via the nucleation and growth of one phase in a surrounding medium or by the spontaneous (spinodal) route because of miscibility of the two components. [22] In some instances, when phase separation happens quickly, preceeding wetting, such blends result in nanoscale phase separation as in the classical case of polymer:fullerene bulk heterojunction organic solar cells. [25] Vertical phase separation, including stratification, occurs when the formation of wetting layers is given sufficient time to progress without the onset of bulk phase separation.…”

Section: Introductionmentioning

confidence: 99%

Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

Wodo

Ren

Khan

et al. 2016

Adv Funct Materials

107

100

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Abstract:Blending of small-molecule organic semiconductors (OSCs) with amorphous polymers is known to yield high performance organic thin film transistors (OTFTs). Vertical stratification of the OSC and polymer binder into well-defined layers is crucial in such systems and their vertical order determines whether the coating is compatible with a top and/or a bottom gate OTFT configuration. Here, we investigate the formation of such blends prepared via spincoating in conditions which yield bilayer and trilayer stratifications, and use a combination of experimental and computational tools to study the competing effects of formulation thermodynamics and process kinetics in mediating the final vertical stratification. We show that trilayer stratification (OSC/polymer/OSC) is the thermodynamically favored configuration and that formation of the buried OSC layer can be kinetically inhibited in certain conditions of spincoating, resulting in a bilayer stack instead. Our analysis reveals that preferential loss of the Zhao et al., Adv. Func. Mater. 2016 2 OSC, combined with early aggregation of the polymer phase due to rapid drying, inhibit the formation of the buried OSC layer. We then moderate the fluid dynamics and drying kinetics during spin-coating to promote trilayer stratification with a high quality buried OSC layer which yields unusually high mobility >2 cm 2 V -1 s -1 in the bottom-gate top-contact configuration.

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“…Intermolecular interactions can lead to blend phase separation. While phase separation in bulk samples leads to isotropic domain structures 11,12 , strongly anisotropic domains up to a self-stratified film are expected in the vicinity of any surface confining a bulk sample 13,14 . Interactions with the substrate and the vacuum surfaces can add dewetting as a further structure directing mechanism.…”

Section: Introductionmentioning

confidence: 99%

Interface control in organic heterojunction photovoltaic cells by phase separation processes

et al. 2007

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Significant progress is being made in the photovoltaic energy conversion using organic semiconducting materials. One of the focuses of attention is the nanoscale morphology of the donor-acceptor mixture, to ensure efficient charge generation and loss-free charge transport at the same time. Using small molecule and polymer blend systems, recent efforts highlight the problems to ensure an optimized relationship between molecular structure, morphology and device properties. Here, we present two examples using a host/guest mixture approach for the controlled, sequential design of bilayer organic solar cell architectures that consist of a large interface area with connecting paths to the respective electrodes at the same time. In the first example, we employed polymer demixing during spin coating to produce a rough interface: surface directed spinodal decomposition leads to a 2-dimensional spinodal pattern with submicrometer features at the polymer-polymer interface. The second system consists of a solution of a blend of small molecules, where phase separation into a bilayer during spin coating is followed by dewetting. For both cases, the guest can be removed using a selective solvent after the phase separation process, and the rough host surface can be covered with a second active, semiconducting component. We explain the potential merits of the resulting interdigitated bilayer films, and explore to which extent polymer-polymer and surface interactions can be employed to create surface features in the nanometer range.

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Interfacial Phenomena in Thin Polymer Films: Phase Coexistence and Segregation

Cited by 93 publications

References 237 publications

Using neutron reflectivity to determine the dynamic properties of a copolymer in a homopolymer matrix

Using neutron reflectivity to determine the dynamic properties of a copolymer in a homopolymer matrix

Vertical Phase Separation in Small Molecule:Polymer Blend Organic Thin Film Transistors Can Be Dynamically Controlled

Interface control in organic heterojunction photovoltaic cells by phase separation processes

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