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ELECTRIC FIELD VERSUS SURFACE ALIGNMENT IN CONFINED FILMS OF A BLOCK COPOLYMER MELT A.V. Kyrylyuk, G.J.A. Sevink, A.V. Zvelindovsky, J.G.E.M. Fraaije Leiden University, P.O.Box 9502, 2300 RA Leiden, The Netherlands email: a.kiriluk@chem.leidenuniv.nl ABSTRACT The dynamics of alignment af a block copolymer microstructure in thin films in the presence of an external electric filed has been studied numerically. We considered in detail a symmetric diblock copolymer melt, exhibiting a lamellar morphology. The method used is a dynamic mean-field density functional method, derived from the generalized time-dependent Ginzburg-Landau theory. We allow for a slight compressibility by adding a Helfand penalty function to the free energy. We investigated the effect of an electric filed on block copolymers under the assumption that the dipolar interaction induced due to the fluctuations of composition pattern is a dominant mechanism of electric field induced domain alignment. As a result, depending on the ratio between electric filed and interfacial interactions, perpendicular, parallel or intermediate (mixed) final lamellar structures were obtained. The intermediate mixed structures remains to be stable, though these structures do not correspond to the minimum of the free energy. While alignment process, the mesophases passes through fascinating states of coexistence of several lamellae clusters with different orientations.
MACROMOLECULES AT INTERFACES, A FLEXIBLE THEORY FOR HARD SYSTEMS F.A.M. Leermakers Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Dreijenplein 6, 6703 HB Wageningen, The Netherlands email: frans@fenk.wau.nl ABSTRACT On January 11 1985 Jan Scheutjens defended his thesis entitled “Macromolecules at interfaces, a flexible theory for hard systems”. In this thesis the Scheutjens-Fleer self-consistent field SF-SCF theory is presented and applied mainly, but not exclusively, to homopolymers at interfaces. It condensed the work done over a period of about 10 years in close harmony with Gerard Fleer and several MSc students of whom I was one, into a booklet of 168 pages. In retrospect one can say that Jan re-invented (almost single-handedly) the selfconsistent-field method. In the early days (before 1980) there was no knowledge in laboratory of Physical Chemistry and Colloid Science in Wageningen about comparable approaches in quantum mechanics. Also the close relation of his work to the Edwards diffusion equation was not known. The work has long been (and still is) associated to lattice models. The reason for this is clear, because the deep understanding of the theory was based on counting conformations and interactions of polymer chains on a lattice. The goal of this lecture is to prove that the discretisation scheme of Scheutjens (and Fleer) of the self-consistent field equations for polymer adsorption is even today a very powerful, flexible tool to obtain better insights in hard systems such as macromolecules at interfaces. I will do this in the context of the state of the art 10 years ago (when Jan passed away). I will discuss a new self-consistent-field method, that better than in the classical SF-SCF approach, accounts for the intra-molecular excluded-volume effects of the polymer molecules. The method that has been developed together with Ph.D’s Jan van Male and Jos van den Oever, features translationally constraint molecules in a two-gradient cylindrical coordinate system. The equilibrium between chains in the bulk and near the surface can only be established by hand. For this the accurate evaluation of appropriate thermodynamic quantities is necessary. A selection of applications will be discussed. Homopolymer adsorption The theory of homopolymers at solid–liquid interfaces was the first problem considered by Jan Scheutjens. It also turns out to be (numerically) one of the hardest problems. The adsorption-desorption transition in polymer adsorption is smooth. It is shown that the polymer conformation near the adsorption transition transforms from the coil to the pancake. The radius scales as R ∝ α g N , whereα ≈ 0.6 for the coil and α = 3 / 4 for the pancake. Ten years ago, the self-similar scaling in the central region of the polymer adsorption profile was basically understood (Van der Linden worked in close cooperation with the Strasbourg group on this issue) from a ground-state approximation. However, the mean-field power law ϕ ( ) ∝ −2 z z that was found in the limit of long chains and strong adsorption, of course deviated from the prediction of De Gennes: ϕ ( ) ∝ −4/3 z z . The failure was often attributed to the fact that ‘correlations’ were neglected. The new method (still being a mean-field theory) is in reasonable agreement with the result of De Gennes.
Page 1 and 2: Frontis - Wageningen International
Page 3 and 4: Prof. dr. Hans Fraaije Leiden Unive
Page 5 and 6: Prof. Ullrich Steiner University of
Page 7 and 8: Preface Self-consistent field model
Page 9 and 10: covered by polymers), and R. Rajago
Page 11 and 12: FIRST-ORDER WETTING TRANSITION AT F
Page 13 and 14: MOLECULAR SCF MODELLING OF PORES IN
Page 15 and 16: COLLAPSE OF POLYMER BRUSHES GRAFTED
Page 17 and 18: SURFACE FORCES, SUPRAMOLECULAR POLY
Page 19 and 20: SWEET BRUSHES: SYNTHESIS AND INTERF
Page 21 and 22: EFFECT OF MIXING OF TWO CHARGED PHO
Page 23 and 24: Figure 2 show a semi-log comparison
Page 25 and 26: MODELING OF STATIONARY POLYMER DIFF
Page 27 and 28: THEORY AND SIMULATION OF BILAYER ME
Page 29 and 30: Figure 1. Time evolution of the she
Page 31: SALT EFFECT TO RAYLEIGH DROPLETS OF
Page 35 and 36: APPLICATION OF HETEROGENEOUS LATTIC
Page 37 and 38: 8. Linse, P., 1993b. Phase behavior
Page 39 and 40: MODELING INTERFACIAL EFFECTS ON THE
Page 41 and 42: Using this patterned electrode, we
Page 43 and 44: span the gap between the electrodes
Page 45 and 46: desirable to use a probe with a muc
Page 47 and 48: span the gap between the electrodes
Page 49 and 50: MEMBRANE FUSION: RESULTS FROM SIMUL
Page 51 and 52: the transition temperature T * when
Page 53 and 54: PROTEIN ADSORPTION ON SURFACES WITH
Page 55 and 56: MODELLING STRUCTURE AND ADHESION AT
Page 57 and 58: References 1. Fischel, L.B. and The
Page 59 and 60: MULTIDOMAIN CONFORMATIONS OF RANDOM
Page 61 and 62: SUPRAMOLECULAR COORDINATION POLYMER
Page 63 and 64: INFLUENCE OF POLYMERS ON THE BENDIN
Page 65 and 66: SPINODAL DECOMPOSITION IN BINARY PO
Page 67 and 68: PERSISTENCE LENGTH OF WORM-LIKE MIC
Page 69 and 70: For small particles with radius R <
Page 71: MEAN-FIELD THEORY FOR THE ADSORPTIO

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