Self-consistent field theory of block copolymers with conformational asymmetry

Vavasour, J. D.; Whitmore, M. D.

doi:10.1021/ma00077a054

Cited by 140 publications

(166 citation statements)

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“…Over the past decade new synthesis techniques have been developed to synthesis graft copolymers having well-defined molecular architectures [1][2][3] , which allow to control the molecular weight of the backbone and the graft arm, the arm polydispersity, the placement and number of branch points and the number of armes grafted to each branch point. The morphological behaviour of graft copolymers with a complex architecture is predicted by the constituting block copolymer hypothesis [4][5][6][7] and theories for mictoarm stars [8,9] or conformationally asymmetric linear diblocks [10,11] . It has been found that the morphological behavior of regular multigraft copolymers with multiple tri-, tetra-or hexafunctional junction points is generally consistent with the morphologies of their constituting unit [7,12,13] .…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Hysteresis Behaviour of Multigraft Copolymers

Staudinger

Weidisch

Zhu

et al. 2006

Macromolecular Symposia

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Summary: PS-PI multigraft copolymers with tri-tetra-and hexafunctional polystyrene branch points have been studied to investigate the influence of molecular architecture on morphological and tensile properties and to find novel material concepts. It was found that the morphological behaviour of these grafted copolymers can be predicted using theoretical approaches. The number of branch points, however, greatly influences the long-range order of microphase separation. Additionally, two new parameters for adjusting mechanical properties of multigraft copolymers are found in our investigations: 1) functionality of the graft copolymer: tri-, tetra-or hexafunctional and 2) number of branch points per molecule. Tetrafunctional multigraft copolymers show surprising high strain at break values up to 1550 %. With increasing number of branch points strain at break and tensile strength increase, where a linear dependence of mechanical properties on the number of branch points is obvious. Excellent elasticity of tetra and hexafunctional multigraft copolymers at high deformation was proved in hysteresis experiments.

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Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Hysteresis Behaviour of Multigraft Copolymers

Staudinger

Weidisch

Zhu

et al. 2006

Macromolecular Symposia

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“…Delicate balance[3] of chain conformational entropy and repulsive interaction energy between unlike monomers allows block copolymers to readily self-assemble into a number of ordered morphologies. Typical morphologies [3,8,9] include lamellar, cylinder, sphere, gyroid and Fddd network phases, which have been proven to be equilibrium states.Experimentally, the balance of the energy and entropy can be tuned by a number of molecular characteristics such as molecular weight [3], chain architecture [10,11], conformational asymmetry [12,13], polydispersity [14,15,16,17,18] and temperature. A number of studies [1,2,3,4,5,6,7] have been done to elucidate the effects of molecular weight, polydispersity, conformational asymmetry and temperature on the mircophase separation in linear di-block copolymer melts.…”

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confidence: 99%

Morphology diagrams forA₂Bcopolymer melts: real-space self-consistent field theory

Kumar

Sides

et al. 2012

J. Phys.: Conf. Ser.

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The standard Gaussian model for block copolymermelts M W Matsen -Stability of the fcc structure in block copolymer systems Makiko Nonomura -SCFT simulation and SANS study on spatial distribution of solvents in microphase separation induced by a differentiating non-solvent in a semi-dilute solution of an ultra-high-molecular-weight block copolymer K Ando, T Yamanaka, S Okamoto et al. Abstract. Morphology diagrams for A2B copolymer melts are constructed using real-space self-consistent field theory (SCFT). In particular, the effect of architectural asymmetry on the morphology diagram is studied. It is shown that asymmetry in the lengths of A arms in the A2B copolymer melts aids in the microphase separation. As a result, the disorder-order transition boundaries for the A2B copolymer melts are shown to shift downward in terms of χN, χ and N being the Flory's chi parameter and the total number of the Kuhn segments,respectively, in comparison with the A2B copolymers containing symmetric A arms. Furthermore, perforated lamellar (PL) and a micelle-like (M) microphase segregated morphologies are found to compete with the classical morphologies namely, lamellar, cylinders, spheres and gyroid. The PL morphology is found to be stable for A2B copolymers containing asymmetric A arms and M is found to be metastable for the parameter range explored in this work. IntroductionMicrophase separation in block copolymer melts [1,2,3,4,5,6,7] has motivated the scientific community over the last couple of decades. Delicate balance[3] of chain conformational entropy and repulsive interaction energy between unlike monomers allows block copolymers to readily self-assemble into a number of ordered morphologies. Typical morphologies [3,8,9] include lamellar, cylinder, sphere, gyroid and Fddd network phases, which have been proven to be equilibrium states.Experimentally, the balance of the energy and entropy can be tuned by a number of molecular characteristics such as molecular weight [3], chain architecture [10,11], conformational asymmetry [12,13], polydispersity [14,15,16,17,18] and temperature. A number of studies [1,2,3,4,5,6,7] have been done to elucidate the effects of molecular weight, polydispersity, conformational asymmetry and temperature on the mircophase separation in linear di-block copolymer melts. However, the effects of chain architecture are not that well established. On the computational side, this is primarily due to a large parameter space for the simulations and resulting large number of morphologies, which need to be compared in terms of their free-energy

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“…Values for the statistical segment length have been published in the literature and monomer volumes were calculated from the monomer mass divided by the measured density at 175 8C. The segment lengths for HDPE and PS are 0.63 nm [24,25] and 0.68 nm, [26,27] respectively. The corresponding monomer volumes are 60 6 10 3 and 175 6 10 3 nm -3 , respectively.…”

Section: Resultsmentioning

confidence: 99%