Phase diagram of morphologies formed by the ABC star terpolymer confined in narrow nanopores with varying pore diameters, D, in units of L0. The pore wall has a strong attraction to the A component; the A component is not shown in this figure for reasons of clarity. We plot the isosurfaces of B/C volume fractions (indicated by green/blue color) of morphologies, including three different-shape morphologies for the single-cylinder phase, C1, four single-helix, H1, morphologies with different repeat numbers of B/C domains in a helical period, and one morphology for the double-helix phase, H2. The top views of the single-helix and double-helix morphologies indicate that the repeat number of nBC from left to right is 5, 6, 7, 8, and 10, respectively. For the reason of clarity, only one helix is plotted in the top view of the double-helix morphology.
(a) Free energy of different morphologies relative to that of the single helix with nBC = 5, indicated by the horizontal solid line at ΔF = 0. The plot of the volume-fraction isosurface of a fourfold stacked-disk phase, DK4, is also shown. (b) Free energy of morphologies of the single helix with various nBC. Here the free energy of the helical morphology with nBC = 7 is used as a reference.
Comparison between different free-energy contributions for the morphologies C1, H1 of nBC = 5, and DK4: (a) interfacial energy contributions of UAB and UBC; (b) entropy, S. The dashed lines indicate the first-order transition between C1 and H1.
Free-energy comparisons, at fixed D = 7.8R g (filled symbols) and D = 8.0R g (unfilled symbols), between H1 and H2. Here, we examine two helical periods of H1 and H2. The two dotted lines indicate that H1 has lower free energy than H2 at D = 7.8R g , and inversely at D = 8.0R g .
(a) Pitch angle θ of the single helix for various nBC, as a function of the pore diameter, D. (b) Average B/C-domain thickness, h, along the helix axis, in units of the bulk value of h0. The three unfilled circles indicate those values of h obtained for 2*nBC = 13, 15, and 17, from the top down, respectively, in the case of double helical periods. The dashed lines indicate these transition points between the H1 morphologies with various values of nBC.
Article metrics loading...
Full text loading...