Lamellar Domain Spacings of Diblock Copolymer/Homopolymer Blends and Conformations of Block Chains in Their Microdomains

Abstract

Lamellar domain spacings (D) of blends of a styrene-2-vinylpyridine (SP) diblock copolymer and homopolymers corresponding to the block polymers (S and/or P), of which molecular weights are lower than that of the block polymer, were examined by small-angle X-ray scattering (SAXS), and the dimensions of block chains in the lamellae were investigated by small-angle neutron scattering (SANS). The D's for SP/S/P ternary and SP/S (or SP/P) binary blends increase with increasing the molecular weight of the homopolymers, MH, as well as the volume fraction of the homopolymers, ΦH, in the corresponding lamella. The variations of the D's with ΦH for the blends with homopolymers having different MH's reveal that homopolymers with higher MH are localized at the center of the corresponding lamella, while those with lower MH are distributed throughout the lamella. Moreover, the comparison between the D's for ternary and binary blends with homopolymers having equal MH's implies that the homopolymers in binary blends are more localized than those in ternary blends. In these ternary and binary blends the radii of gyration of styrene block chains along the direction parallel to lamellar interface are not much different from that for a pure diblock copolymer irrespective of ΦH as well as MH.

Nanostructured Thermosets from Self-Assembled Amphiphilic Block Copolymer/Epoxy Resin Mixtures

“…The sequence of morphologies identified in the OP5/BPA348 blends as a function of block copolymer concentration (see Figure 1) mimics prior experimental results obtained with block copolymer/homopolymer blends, [30][31][32][33] as anticipated by meanfield theoretical calculations. 19 This progression of morphologies can be rationalized by considering the PEO chains as brushes extending from the PEO/PEP interface (Figure 5a).…”

Phase Behavior of Symmetric Ternary Block Copolymer-Homopolymer Blends in Thin Films and on Chemically Patterned Surfaces

“…The natural lamellar periods of the H 0, 0.2, and 0.4 blends were calculated based on q to be L B;L 50:7, 56.6, and 69.0 nm, respectively, and in general L B;L L O 1 ÿ H ÿ0:74 for blends with 0:4 where L O is the lamellar periodicity of the pure diblock copolymer. This scaling of lamellar blend periodicity with H is consistent with that found by Torikai et al [15].…”

“…The phase behavior and domain dimensions of symmetric ternary blends is determined by the volume fraction of total homopolymer in the blend, H , and the ratio of the degree of polymerization of the homopolymers to that of the block copolymer, . These materials in the bulk have been characterized as a function of H and using small angle neutron scattering (SANS) [6 -15], small angle x-ray scattering [15][16][17], transmission electron microscopy [7,9,16], rheology [8,18,19], light scattering [9,10,20], and theoretical approaches [21][22][23]. Below the order-disorder transition (ODT) temperature, symmetric ternary blends form lamellae at low H and macrophase separated morphologies at high H .…”

“…Ternary blends may hold some advantages for directed assembly over pure block copolymers because (1) the periodicity of the lamellar blends can be matched to the desired pattern dimensions simply by tuning the blend composition [7,15,16,32] and (2) homopolymer redistribution within the blend domains facilitates the formation of nonregular geometries such as sharp bends [4]. We have therefore characterized the behavior of symmetric ternary blends on chemically striped surfaces with periodicities, L S , from 45 to 110 nm.…”

Monte-Carlo simulation of ternary blends of block copolymers and homopolymers

“…The experimental work by Torikai et al 57 is conducted in bulk, like this study. It proposes that if all A homopolymers are distributed uniformly throughout the A domain and likewise for B homopolymers, then β = 1/3.…”