Modelling of the Phase Separation Behaviour of Semiflexible Diblock Copolymers

Friedel, Peter; John, Andreas; Pospiech, Doris; Jehnichen, Dieter; Netz, Roland R.

doi:10.1002/1521-3919(20020901)11:7<785::aid-mats785>3.0.co;2-e

Cited by 30 publications

(36 citation statements)

References 14 publications

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“…[9][10][11] Furthermore, unlike coil-coil block copolymers which are composed of two blocks exhibiting similar conformations, the assembly of rod and coil blocks to form a single polymer chain induces strong conformational asymmetry and thus original phase separation properties and mechanisms. 12 An increasing number of experimental studies have been carried out during the past 10 years, enabled by remarkable advances in the synthesis of rod-coil block copolymers. Two main approaches for the synthesis of π-conjugated rod-coil block copolymers have been developed: the divergent path consists of the living polymerization of the coil block started from a rod macroinitiator, [13][14][15] whereas in the convergent way the coil block obtained by living polymerization is linked, either quenched [16][17][18] or condensated, [19][20][21][22][23] with the end-functionalized rod.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly of Poly(diethylhexyloxy-p-phenylenevinylene)-b- poly(4-vinylpyridine) Rod−Coil Block Copolymer Systems

et al. 2007

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We describe the synthesis, the morphology, and self-assembly behavior of semiconducting poly-(4-vinylpyridine-b-diethylhexyloxy-p-phenylenevinylene) (P4VP-b-PPV) rod-coil block copolymer systems. Three different block copolymers with 55%, 80%, and 88% coil volume fraction were synthesized by convergent anionic polymerization in THF using lithium R-methylstyrene as initiator. The morphology of the block copolymers was studied by transmission electron microscopy, small-angle X-ray scattering, and small-angle neutron scattering as a function of the volume fraction of the rod block as well as different annealing conditions. The microphaseseparated morphologies in these block copolymers vary from lamellar, to hexagonal, and spherical, when the volume fraction of the rod is progressively reduced. By combining the lattice parameter measured by scattering techniques with the volume fraction of rod domains obtained by nuclear magnetic resonance, it was shown that the block copolymers in the lamellar structure are organized in a smectic C double layer, while in the hexagonal phase they self-organize in a homeotropic arrangement, with the rod blocks forming the dispersed phase. Furthermore, while self-assembly of rod-coil block copolymers in columnar hexagonal phase prevents close rod packing, for the lamellar phase evidence of this configuration among rods is shown by wide-angle X-ray scattering. As a consequence, the morphology and long-range order in the lamellar phase are the result of simultaneous inter-rods liquid crystalline interactions and the tendency to microphase segregation of rod and coil. As a result, depending on temperature, the lamellar phase can exist both with rods oriented in a smectic configuration and with randomly packed rods. We show that annealing the lamellar phase below its order-disorder transition temperature, T ODT , but above the maximum affordable temperature for inter-rods liquid crystalline interactions, called smectic-in-lamellar to lamellar order-disorder transition temperature, T SL (with T SL < T ODT ), leads to highly improved long-range lamellar order, which is then preserved when the system is cooled below T SL , at which temperature rod close packing is fully recovered.

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Section: Introductionmentioning

confidence: 99%

Self-Assembly of Poly(diethylhexyloxy-p-phenylenevinylene)-b- poly(4-vinylpyridine) Rod−Coil Block Copolymer Systems

et al. 2007

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“…Both types of intermolecular forces are expected to greatly affect the phase separation mechanisms. Finally, the strong anisotropy of rod-like blocks introduces large conformational asymmetry effects in rod-coil block copolymers which can have a considerable impact on the perturb self-assembled morphologies compared to coil-coil block copolymers [19]. The steadily increasing number of experimental and theoretical studies devoted to rod-coil block copolymers, has been triggered by the considerable advances in the synthetic 380 The European Physical Journal E routes followed to control their synthesis [5,[20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Self-assembly of rod-coil block copolymers from weakly to moderately segregated regimes

Sary

Brochon²,

Hadziioannou³

et al. 2007

Eur. Phys. J. E

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Abstract. We report on the self-assembly behaviour of two homologue series of rod-coil block copolymers in which, the rod, a π-conjugated polymer, is maintained fixed in size and chemical structure, while the coil is allowed to vary both in molecular weight and chemical nature. This allows maintaining constant the liquid crystalline interactions, expressed by Maier-Saupe interactions, ω, while varying the tendency towards microphase separation, expressed by the product between the Flory-Huggins parameter and the total polymerization degree, χN . Therefore, the systems presented here allow testing directly some of the theoretical predictions for the self-assembly of rod-coil block copolymers in a weakly segregated regime. The two rod-coil block copolymer systems investigated were poly(DEH-p-phenylenevinylene-b-styrene), whose self-assembly takes place in the very weakly segregated regime, and poly(DEH-p-phenylenevinylene-b4vinylpyridine), for which the self-assembly behaviour occurs under increased tendency towards microphase separation, hereby referred to as moderately segregated regime. Experimental results for both systems are compared with predictions based on Landau expansion theories.PACS. 61.46.-w Nanoscale materials -61.30.Vx Polymer liquid crystals -64.60.Cn Order-disorder transformations; statistical mechanics of model systems

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“…Under certain circumstances the rods may form highly oriented, liquid crystalline-like structures whereas the flexible, chain-like parts stay in a wide range of thermodynamic parameters disordered. In several articles, [1][2][3][4][5][6][7][8][9][10] the phase diagram for melts of rod-coil polymers is studied as an extension of the case of flexible copolymers under different architecture. For example, significant work has been done for di-and triblock rod-coil copolymers using scaling arguments, see ref.…”

Section: Introductionmentioning

confidence: 99%

Rod‐Coil Globular Structures – Simple Models for Proteins

Nowak

Rostiashvili

Vilgis

2004

Macro Chemistry & Physics

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Summary: In this article, we discuss the phase behavior of rod‐coil copolymers with two main methods. First, a scaling theory on different conformations is presented, which shows how micelles form. The circumstances of their stability is discussed. In the second part, we have formulated the general self‐consistent field theory (SCFT) for the rod(or helix)‐coil multiblock copolymer globule. This model and both approaches provide a simple description of the interplay between the secondary and tertiary structures in a globule α‐helix proteins.Pictorial representation of a used series ratio: each bar, zigzag line and fat dot correspond to $\hat G_{{\rm rod}} ,\;\hat G_{{\rm coil}} ,$ and σ1/2, respectively.magnified imagePictorial representation of a used series ratio: each bar, zigzag line and fat dot correspond to $\hat G_{{\rm rod}} ,\;\hat G_{{\rm coil}} ,$ and σ1/2, respectively.

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Modelling of the Phase Separation Behaviour of Semiflexible Diblock Copolymers

Cited by 30 publications

References 14 publications

Self-Assembly of Poly(diethylhexyloxy-p-phenylenevinylene)-b- poly(4-vinylpyridine) Rod−Coil Block Copolymer Systems

Self-Assembly of Poly(diethylhexyloxy-p-phenylenevinylene)-b- poly(4-vinylpyridine) Rod−Coil Block Copolymer Systems

Self-assembly of rod-coil block copolymers from weakly to moderately segregated regimes

Rod‐Coil Globular Structures – Simple Models for Proteins

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