Mechanisms of ordering in block copolymer sub-monolayer films upon selective solvent annealing

Dewetting behavior of Langmuir−Blodgett films of polystyrene‐b‐poly(methyl methacrylate) induced by solvent vapor annealing

“…In our minds, it is worthwhile and possible to compare the SVA effect on the dewetting of the ultrathin spin‐coated and LB films with similar initial thickness of several nanometers. Actually, ultrathin BCP films that are spin‐coated usually exhibit disordered structures since vitrification as a result of the rapid solvent evaporation and geometric confinement prevent the development of microphase separation along with chain movement . In contrast, LB films with well‐defined two‐dimensional structures would thus provide a convenient platform for assessing SVA.…”

Effects of copolymer composition, film thickness, and solvent vapor annealing time on dewetting of ultrathin block copolymer films

“…A reasonable schematic illustration is given to describe the whole dewetting process of the SMMA34K films with different initial thicknesses. As far as we know, only a few studies were done on dewetting of ultrathin copolymer films (<20 nm thick) induced by solvent vapor annealing and the final droplet evolution was not reported [27,31,37,38]. It is well known that droplets with a wide distribution usually exhibit in polymer films induced in different dewetting processes.…”

“…The pattern totally disappears with the further annealing and it should not be regarded as microphase separation structure according to the low phase contrast in its phase image (Fig. S1), which is because microphase separation is usually suppressed in ultrathin films due to geometric confinement [37]. Furthermore, on the basis of BCP phase diagram, the vN parameter is given to be 16 at disordering condition for a cylinder-forming BCP with an asymmetric u = 0.75 (here v is the Flory-Huggins segmental interaction parameter between the two blocks).…”

“…Peng et al systematically studied the morphologies of some polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) films annealed in various solvent vapors, and they found that PMMA-selective acetone vapor could induce thin film dewetting, while neutral and PS-selective solvents could not [36]. As far as we know, only a few studies were done on dewetting of ultrathin copolymer films (<20 nm thick) induced by solvent vapor annealing and the final droplet evolution was not reported [27,31,37,38]. In this work, we used acetone vapor to induce dewetting of PS-b-PMMA films on hydrophilic silicon substrates.…”

Exploring the Self-Assembly Capabilities of ABA-Type SBS, SIS, and Their Analogous Hydrogenated Copolymers onto Different Nanostructures Using Atomic Force Microscopy

“…As morphologies with highly ordered domains are needed for most of those applications, the different orientations of block copolymer domains in the self-assembled morphologies are very crucial and attract a lot of interest. Several methods are used for the ordering and alignment of block copolymers: chemical patterning [ 42 , 43 ], electric-field alignment [ 42 , 43 , 44 ], graphoepitaxy [ 42 , 43 , 44 ], contact line pinning [ 42 ], soft lithography [ 42 ], shear alignment [ 42 , 43 ], directional crystallization [ 42 , 43 ], and thermal or solvent vapor annealing [ 44 ], among others.…”