Copolymers grain size

The self-assembly of block polymers, in the bulk, thin film and solution states, produces uniformly sized nanostructured patterns that are very useful for nanofabrication. Optimal utilization of these nanoscopic patterns requires complete spatial and orientational control of the microdomains. However, the microdomains in the bulk state normally have grain sizes in the submicron range and have random orientations. In block copolymer thin films, the natural domain orientations are generally not desirable for nanofabrication. In particular, for composition-asymmetric cylindrical thin films, experimental... 

The metallic layers were examined either by conventional or cross-section TEM in a Jeol 200 Cx microscope. For the cross section preparation a sandwich of two laminates is made, glued face to face with an epoxy, cut in small pieces, mechanically polished, and then ion milled to a final TEM observation thickness. The plane section TEM sample are prepared by dissolving the PET in trifluoroacetic acid for 5 to 10 mn. The area observed, on plane section TEM, for the grain size calculation is close to 0.2 urn. For the adhesion measurements, test pieces consist of aluminum support (1 mm thick) double sided tape (Permacel P-94) PET (12pm) / evaporated aluminum/ ethylene acrylic acid (EAA) copolymer film. These laminates are prepared for the peel test by compression under 1.3 105 N.m2 at 120°C for 10 seconds. The peel test is performed by peeling the EAA copolymer sheet from the laminate in an INSTRON tensile tester at 180° peel angle and 5 cm min peel rate. 

Diblock copolymers with roughly equal block lengths can microphase— separate into a lamellar phase, with alternating layers of mostly A monomer and mostly B monomer. When quenched into the lamellar phase from the isotropic phase, these layers form roughly parallel to each other locally. A polydomain texture is created from this quenching, with a typical grain size of order 0.1 pm. The oscillatory shear response of such a quenched sample is observed to have at the lowest measurable frequencies. Can this observed response be the real terminal response of the sample Is this sample a viscoelastic solid or a viscoelastic liquid ... 

Fig. 5.13 When confined to a thin fihn, the orientation of block copolymer domains with respect to the substrate surface is crucial for many applications, (a) Lamellae lying parallel to the substrate, (b) lamellae aligned perpendicular, (c) cylinders lying parallel, (d) cylinders perpendicular, and (e) spheres. In the case of lamellae in the perpendicular orientation and cylinders in parallel, lines can be patterned if the persistence length of the structure can be controlled. In the case of upright cylinders and spheres, the grain size and perfection of the hexagonal array is of primary importance. Reproduced with permission from ref. [105]...

Colson JP, Eby RK (1966) Melting temperatures of copolymers. J Appl Phys 37 3511-3514 Evans UR (1945) The laws of expanding circles and spheres in relation to the lateral growth of surface films and the grain-size of metals. Trans Faraday Soc 41 365-374 Fischer EW (1957) Stufen- und spiralfijrmiges Kristallwachstum bei Hochpolymeren. Z Naturforsch 12a 753-754... 

Ultra-Small Angle X-niy Scattering and Transmission Electron Microscopy Studies Probing Grain Size of LameUar Styrene-Butadiene Block Copolymers... 

Bondzic, S., Polushldn, E., Schouten, A.J. et al. (2007) The influence of grain size on the aUgnment of hexagonally ordered cyUnders of self-assembled diblock copolymer-based supramolecules. Polymer, 48,4723 732. 

The allyl alcohol copolymer with vinyl acetate, used as a self-contained stabilizer during the polymerization of vinyl acetate, forms a porous product with a relatively large dispersion of grain sizes. 

Alternatively, one can directionally solidify a crystallizable material for the purposes of templating the orientation of microdomains. Researchers have shown that benzoic acid can be suitably crystallized and polystyrene-polyethylene diblock copolymers that are dissolved into benzoic acid will form microdomains with an orientation perpendicular to the substrates [62]. While this is very powerful, it not clear that suitable solvents can be found for a wide variety of copolymer systems such that this can be generalized. Additionally, the grain size of the cylinders is very small, so that addressability of the cylinders is rendered difficult. 

Low-angle light-scattering (LALS) has proved useful in studying some of the coarser features of interest in block copolymer morphology such as grain size, and sperulitic textures in systems containing crystallizable blocks. ... 

A thin layer of crosslinked block copolymer can also act as a pattern upon which a thicker lamellar morphology can assemble perpendicularly. For the crosslinked underlayer, Park et al. used a monolayer of lamellar PS-b-PMMA oriented perpendicularly via a neutral substrate underlayer, while Ruiz et al. used parallel cylinders, which form larger grains than perpendicular lamellae, to direct a block copolymer with perpendicular lamellae deposited on top to form with large grain size. °°... 

In the suspension polymerization of PVC, droplets of monomer 30—150 p.m in diameter are dispersed in water by agitation. A thin membrane is formed at the water—monomer interface by dispersants such as poly(vinyl alcohol) or methyl cellulose. This membrane, isolated by dissolving the PVC in tetrahydrofuran and measured at 0.01—0.02-p.m thick, has been found to be a graft copolymer of polyvinyl chloride and poly(vinyl alcohol) (4,5). Early in the polymerization, particles of PVC deposit onto the membrane from both the monomer and the water sides, forming a skin 0.5—5-p.m thick that can be observed on grains sectioned after polymerization (4,6). Primary particles, 1 p.m in diameter, deposit onto the membrane from the monomer side (Pig. 1), whereas water-phase polymer, 0.1 p.m in diameter, deposits onto the skin from the water side of the membrane (Pig. 2) (4). These domain-sized water-phase particles may be one source of the observed domain stmcture (7). 

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