Microphase Separation in Poly(oxyethylene)−Poly(oxybutylene) Diblock Copolymers

Shaomin,; Fairclough, J. Patrick A.; Terrill, Nicholas J.; Turner, Simon C.; Hamley, Ian W.; Matsen, Mark W.; Ryan, Anthony J.; Booth, Colin

doi:10.1021/ma981089k

Cited by 64 publications

(71 citation statements)

References 38 publications

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“…Rather, it suffices to choose values that map our χ model system qualitatively onto the experimental structure. A relationship between (or in this χ case, N) and temperature T that is commonly used is [40,41] These values produce reasonable interfacial structures, as shown in Figure 5 for T=2.0 and T=2.5 at the two different pressures. To assign specific units to the temperature such as Kelvin or degrees centigrade, the parameters A should be specified in the desired units.…”

Section: Surface Tension As a Function Of Temperature And Pressurementioning

confidence: 99%

Effect of Temperature and Pressure on Surface Tension of Polystyrene in Supercritical Carbon Dioxide

et al. 2007

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This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry B, copyright 2007 © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see DOI: 10.1021/jp065851tThe surface tension of polymers in a supercritical fluid is one of the most important physicochemical parameters in many engineering processes, such as microcellular foaming where the surface tension between a polymer melt and a fluid is a principal factor in determining cell nucleation and growth. This paper presents experimental results of the surface tension of polystyrene in supercritical carbon dioxide, together with theoretical calculations for a corresponding system. The surface tension is determined by Axisymmetric Drop Shape AnalysisProfile (ADSA-P), where a high pressure and temperature cell is designed and constructed to facilitate the formation of a pendant drop of polystyrene melt. Self-consistent field theory (SCFT) calculations are applied to simulate the surface tension of a corresponding system, and good qualitative agreement with experiment is obtained. The physical mechanisms for three main experimental trends are explained using SCFT, and none of the explanations quantitatively depend on the configurational entropy of the polymer constituents. These calculations therefore rationalize the use of simple liquid models for the quantitative prediction of surface tensions of polymers. As pressure and temperature increase, the surface tension of polystyrene decreases. A linear relationship is found between surface tension and temperature, and between surface tension and pressure; the slope of surface tension change with temperature is dependent on pressure.

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Section: Surface Tension As a Function Of Temperature And Pressurementioning

confidence: 99%

Effect of Temperature and Pressure on Surface Tension of Polystyrene in Supercritical Carbon Dioxide

et al. 2007

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“…1−4 Numerous experimental and theoretical studies have shown that the morphology and domain spacing of nanophase-separated block copolymers can be predictably controlled by varying the degree of polymerization ( N ), the volume fraction ( f ), and the interaction parameter between blocks (χ). 5−10 Block copolymers containing polydimethylsiloxane (PDMS) are particularly desirable, as the generally high incompatibility between siloxanes and many organic components facilitates ordered phase separation at low N , yielding correspondingly small features. 11,12 For example, our group has utilized the high χ and etch contrast between blocks in PDMS- b -poly(lactic acid) to create ordered arrays of sub-20 nm features.…”

Section: Introductionmentioning

confidence: 99%

End Groups of Functionalized Siloxane Oligomers Direct Block-Copolymeric or Liquid-Crystalline Self-Assembly Behavior

et al. 2016

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Monodisperse oligodimethylsiloxanes end-functionalized with the hydrogen-bonding ureidopyrimidinone (UPy) motif undergo phase separation between their aromatic end groups and dimethylsiloxane midblocks to form ordered nanostructures with domain spacings of <5 nm. The self-assembly behavior of these well-defined oligomers resembles that of high degree of polymerization (N)–high block interaction parameter (χ) linear diblock copolymers despite their small size. Specifically, the phase morphology varies from lamellar to hexagonal to body-centered cubic with increasing asymmetry in molecular volume fraction. Mixing molecules with different molecular weights to give dispersity >1.13 results in disorder, showing importance of molecular monodispersity for ultrasmall ordered phase separation. In contrast, oligodimethylsiloxanes end-functionalized with an O-benzylated UPy derivative self-assemble into lamellar nanostructures regardless of volume fraction because of the strong preference of the end groups to aggregate in a planar geometry. Thus, these molecules display more classically liquid-crystalline self-assembly behavior where the lamellar bilayer thickness is determined by the siloxane midblock. Here the lamellar nanostructure is tolerant to molecular polydispersity. We show the importance of end groups in high χ–low N block molecules, where block-copolymer-like self-assembly in our UPy-functionalized oligodimethylsiloxanes relies upon the dominance of phase separation effects over directional end group aggregation.

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“…Block copolymers have been the subject of much research over the last three decades, largely due to the interesting behaviour of amphiphilic species [25][26][27][28][29][30][31]. In these polymeric systems the blocks show differing affinity towards a potential solvent and, frequently, a tendency to avoid mixing of dissimilar blocks with one another.…”

Section: Introductionmentioning

confidence: 99%

Toughening by nanostructure

Ruiz‐Pérez

Royston

Fairclough

et al. 2008

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a b s t r a c tBlock copolymer modified epoxy resins have generated significant interest since it was demonstrated that the combination could lead to nanostructured thermosets through self-assembly. Over moderate to high polymer concentration the system behaves as expected for a block copolymer in a solvent selective for one block. Two types of copolymers have been studied: non-reactive and reactive modifiers. Morphologies such as copolymer vesicle and spherical/wormlike micelles can be formed under the appropriate conditions. The enhancement of the modified thermosets' mechanical properties depends on the morphology adopted by the polymers. Besides improving mechanical properties, the morphology was found to also have an effect on the glass transition in the studied systems. In this review we collect the available data on the block copolymers used to fabricate nanostructured epoxy resins and critically appraise the properties reported.

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Microphase Separation in Poly(oxyethylene)−Poly(oxybutylene) Diblock Copolymers

Cited by 64 publications

References 38 publications

Effect of Temperature and Pressure on Surface Tension of Polystyrene in Supercritical Carbon Dioxide

Effect of Temperature and Pressure on Surface Tension of Polystyrene in Supercritical Carbon Dioxide

End Groups of Functionalized Siloxane Oligomers Direct Block-Copolymeric or Liquid-Crystalline Self-Assembly Behavior

Toughening by nanostructure

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