Morphology transition from cylindrical to lamellar microdomains of block copolymers

Sakurai, Shinichi; Momii, Toshikazu; Taie, Kazuhiro; Shibayama, Mitsuhiro; Nomura, Shunji; Hashimoto, Takeji

doi:10.1021/ma00055a013

Cited by 143 publications

(142 citation statements)

References 11 publications

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“…30 Besides varying the parameter, OOTs can also be achieved utilizing supramolecular comb-coil diblock copolymers, as has been demonstrated previously. 26,31 Comb-coil diblock copolymers consist of a coil block and a comb block, where side chains are regularly grafted to a usually flexible backbone.…”

Section: Introductionmentioning

confidence: 87%

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

et al. 2006

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Hydrogen-bonding amphiphilic low molecular weight plasticizing compounds to one block of diblock copolymers to form supramolecular comblike blocks leads to hierarchical self-assembly at the block copolymer (long) and amphiphile (short) length scales, in which lamellar-in-lamellar order and the related phase transitions have previously been shown to allow thermal switching of electrical and optical properties [Science 1998, 280, 557; Nat. Mater. 2004, 3, 872]. In this work other hierarchies and phase transitions are systematically searched, a particular interest being hierarchies containing gyroid structures and the related order−order transitions. Polymeric supramolecular comb−coil diblock copolymers consisting of a polystyrene (PS) coillike block and a supramolecular comblike block based on poly(4-vinylpyridine) (P4VP) are used, where the pyridines are either directly hydrogen bonded with 3-pentadecylphenol (PDP), i.e., PS-block-P4VP(PDP)1.0, or first protonated with methanesulfonic acid (MSA) and then hydrogen bonded to PDP, i.e., PS-block-P4VP(MSA)1.0(PDP)1.0. In this way the comblike block can be noncharged or charged. The morphologies were determined using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) at different temperatures. In the case of PS-block-P4VP(PDP)1.0, all classical diblock copolymer morphologies were observed at room temperature, where the P4VP(PDP)1.0 domains contain an additional lamellar structure due to the supramolecular comblike blocks. Here we report novel gyroid and hexagonal perforated layer morphologies, i.e., where the PS and P4VP(PDP)1.0 blocks form gyroid or hexagonal perforated layer order and the P4VP(PDP)1.0 domains have an internal lamellar order. Heating past ca. T = 60 °C causes an order−disorder transition within the P4VP(PDP)1.0 domains. Further heating leads to gradually reduced hydrogen bonding strength, and importantly PDP becomes soluble in PS at T > ca. 120 °C. At such temperatures PDP is found in both the P4VP and PS domains, thus leading to changes in the relative volume fractions of the domains, which in turn leads to order−order transitions. In PS-block-P4VP(MSA)1.0(PDP)1.0, typically lamellar and cylindrical block copolymeric structures were observed, where there was an additional internal lamellar order within the P4VP(MSA)1.0(PDP)1.0 domains. Coincidentally, an order−disorder transition within the P4VP(MSA)1.0(PDP)1.0 domains takes place at T = ca. 125 °C. Above that temperature, PDP is in both PS and P4VP(MSA)1.0 domains, but most interestingly at ca. T > 175 °C PDP becomes a nonsolvent for P4VP(MSA)1.0 and it is therefore expelled to predominantly to the PS domains. This manifests as an order−order transition. All samples exhibit at least two thermoreversible order−order transitions, and some of them show even five consecutive self-assembled phases as a function of temperature. Besides being amphiphilic, PDP can also be regarded as a plasticizer, i.e., relatively nonvolatile solvent, for the P4VP, PS, and P4VP(MSA)1.0 with cha...

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Section: Introductionmentioning

confidence: 87%

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

et al. 2006

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“…Their molecules are composed of blocks usually immiscible with each other, resulting in phase-separated structures at the nanometer level. According to the thermodynamic affinity between the blocks of a copolymer, as well as their absolute and relative length, block copolymers can present different types of morphologies, the most common ones being the spherical, lamellar, and cylindrical structures [1][2][3][4][5][6]. In particular, styrenic block copolymers such as polystyrene-b-polyisoprene-b-polystyrene (SIS) and polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene triblock copolymers (SEBS) have drawn the attention of the industry, as they can be used as thermoplastic elastomers (TPE) due to their structure composed of immiscible rigid (styrene) and flexible blocks (such as ethylene-co-butylene (EB), butadiene, or isoprene) [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Morphological evolution of block copolymer nanocomposites submitted to extensional flows

Amurin¹,

Carastan²,

Demarquette³

2016

Journal of Rheology

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In this work, the effect of extensional flow on the morphology of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymers and their clay-containing nanocomposites was evaluated. Four types of SEBS copolymers with different block compositions and cylindrical morphology were chosen to understand the effects of cylinder orientation and state of clay dispersion on the evolution of morphology during extensional flow. The effect of clay concentration (ranging from 2.5 to 7.5 wt. %) was also studied. The samples were subjected to extensional flow using a Sentmanat extensional rheometer attached to a rotational rheometer at Hencky strain rates varying from 0.01 to 20 s À1 . Small angle X-ray scattering analysis was subsequently performed to evaluate the morphological changes caused by extensional flow. When preoriented block copolymers [SEBS-30% PS (polystyrene)] and their nanocomposites undergo elongation, the styrene cylinders and clay nanoparticles align themselves in the flow direction and their rheological behavior and morphological evolution are influenced by the stretching direction (longitudinal and transverse), strain rate magnitude, clay concentration, and dispersion state of the clay nanoparticles. When isotropic block copolymers (SEBS-13% PS) undergo elongation, it was observed that the PS cylinders only exhibit structural alignment in the stretching direction in the presence of clay. Block copolymer molecules can exhibit different relaxation times depending upon the volume fraction of PS domains (13% or 30%). The addition of clay, however, hinders complete relaxation, helping to promote a permanent domain alignment after flow cessation, especially in hard-to-align copolymers. V C 2016 The Society of Rheology.

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“…Sakurai et al examined the reverse transition in poly͑styrene-block-butadiene-block-styrene͒ triblock copolymers, where a nonequilibrium cylinder phase produced by a selective solvent transforms into a stable lamellar phase upon annealing. 27 It appears that they were also observing spinodal decomposition, although the existence of isolated regions of the metastable cylinder phase in their system is interesting. Floudas et al have studied kinetics of the lamellarto-cylinder transition in poly͑isoprene-block-ethylene oxide͒ where the ethylene oxide block is crystalline in the lamellar phase.…”

Section: Introductionmentioning

confidence: 99%

Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt

Wickham

Shi

Wang

2003

The Journal of Chemical Physics

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The nucleation of a droplet of stable cylinder phase from a metastable lamellar phase is examined within the single-mode approximation to the mean-field Landau-Brazovskii model for diblock copolymer melts. By employing a variational ansatz for the droplet interfacial profile, an analytic expression for the interfacial free energy of an interface of arbitrary orientation between cylinders and lamellae is found. The interfacial free energy is anisotropic and is lower when the cylinder axis is perpendicular to the interface than when the cylinders lie along the interface. Consequently, the droplet shape computed via the Wulff construction is lens like, being flattened along the axis of the cylinders. The size of the critical droplet and the nucleation barrier are determined within classical nucleation theory. Near the lamellar-cylinder phase boundary, where classical nucleation theory is applicable, critical droplets of size 30-400 cylinders across with aspect ratios of 4 -10 and nucleation barriers of (30-40)k B T are typically found. The general trend is to larger critical droplets, higher aspect ratios, and smaller nucleation barriers as the mean-field critical point is approached.

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Morphology transition from cylindrical to lamellar microdomains of block copolymers

Cited by 143 publications

References 11 publications

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

Self-Assembled Structures in Diblock Copolymers with Hydrogen-Bonded Amphiphilic Plasticizing Compounds

Morphological evolution of block copolymer nanocomposites submitted to extensional flows

Nucleation of stable cylinders from a metastable lamellar phase in a diblock copolymer melt

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