Computational Design of High-χ Block Oligomers for Accessing 1 nm Domains

Abstract

Molecular dynamics simulations are used to design a series of high-χ block oligomers (HCBOs) that can self-assemble into a variety of mesophases with domain sizes as small as 1 nm. The exploration of these oligomers with various chain lengths, volume fractions, and chain architectures at multiple temperatures reveals the presence of ordered lamellae, perforated lamellae, and hexagonally packed cylinders. The achieved periods are as small as 3.0 and 2.1 nm for lamellae and cylinders, respectively, which correspond to polar domains of approximately 1 nm. Interestingly, the detailed phase behavior of these oligomers is distinct from that of either solvent-free surfactants or block polymers. The simulations reveal that the behavior of these HCBOs is a product of an interplay between both "surfactant factors" (headgroup interactions, chain flexibility, and interfacial curvature) and "block polymer factors" (χ, chain length N, and volume fraction f). This insight promotes the understanding of molecular features pivotal for mesophase formation at the sub-5 nm length scale, which facilitates the design of HCBOs tailored toward particular desired morphologies.

Rapid access to discrete and monodisperse block co-oligomers from sugar and terpenoid toward ultrasmall periodic nanostructures

“…Therefore, strong segregation between hydrophilic saccharidic blocks and hydrophobic isoprene-based hydrocarbon chains would be expected, which would in turn allow microphase separation in the molecular-weight regime below 2000 g mol −1 . In addition, recent reports [33][34][35] by Lodge, Siepmann, and Hillmyer on sugarbased amphiphiles with a hydrocarbon chain, leading to a lamellar morphology with d of 3.5 nm (even down to d of 1.2 nm as revealed by molecular dynamic simulation), also supports that the combination of sugars and terpenoids is highly promising for realizing ultrasmall nanostructure formation. More importantly, oligosaccharide and terpenoid blocks showing defined and discrete degrees of polymerization (DPs) are commercially available, and a series of BCOs featuring monodispersity and discrete DPs can be synthesized readily from them, providing rapid access to various ultrasmall nanostructures showing diverse morphologies, features, and sizes.…”

Multifunctional Structured Platforms: From Patterning of Polymer-Based Films to Their Subsequent Filling with Various Nanomaterials

“…Although, as pointed out by Kim et al additional challenges such as selectivity of etching or density of patterns [211] still need to be controlled and further improved; BCPL can already overcome limitations of conventional photo-, beam-, and soft lithography, and it can not only produce sub-10 nm scale features [26,214,217,219,225], but it can also lead to the fabrication of sub-5 nm relief patterns [196,199,213,226] (Figure 12a). In the future, this could be further improved as theory simulations predict the possibility to access sub-2 nm domains when employing the self-assembly of model amphiphiles [227] or even 1 nm-sized domains when making use of oligomers [228] (Figure 12b). Nonetheless, this high lateral resolution might come often with challenges such as mechanical stability [196].…”

“…In the past years, BCPL was widely used in nanotechnological applications [200,208,211,217], including opto- [207] and microelectronics [228]. This method has proven itself to be a highly promising method, especially because it relies on a multitude of ordered structures obtained by directed and self-assembly such as parallel or perpendicularly oriented lamellar structures [26,219,221,225,226,228,229], (hexagonally packed) cylinders [26,199,217], semispherical [197] or body-centered cubic spherical structures [26], nanomesh structures [209], strand structures [222], double-gyroids [26], square, rectangular, and rhombic arrays of BCPs [220], quasi-hexagonal micellar structures [216], Archimedean tilings [200], and more [195,212,213,215,218,232].…”

“…In the past years, BCPL was widely used in nanotechnological applications [200,208,211,217], including opto- [207] and microelectronics [228]. This method has proven itself to be a highly promising method, especially because it relies on a multitude of ordered structures obtained by directed and self-assembly such as parallel or perpendicularly oriented lamellar structures [26,219,221,225,226,228,229], (hexagonally packed) cylinders [26,199,217], semispherical [197] or body-centered cubic spherical structures [26], nanomesh structures [209], strand structures [222], double-gyroids [26], square, rectangular, and rhombic arrays of BCPs [220], quasi-hexagonal micellar structures [216], Archimedean tilings [200], and more [195,212,213,215,218,232]. Moreover, other more complex 2D [195] and hierarchical [195] or non-native [232] 3D BCP structures can be obtained via multiple self-assembly (because the fabrication of ordered structures requires an extremely precise control over ordering in BCP thin films [229], the latter can be further improved [216,218] inclusively through the use of chemical vapor deposition [201]).…”

Engineering block copolymer materials for patterning ultra-low dimensions

“…Siepmann and co-workers explored the limit of segregated systems and conceptualized the perfect system leading to the smallest CD possible using computational simulations. 139,140 Amphiphilic block cooligomers that act in the boundaries between nonionic surfactants and BCPs were calculated to form lamellae and cylinders domain size as small as 3 and 2.1 nm, respectively. Adapting mean field theory to block co-oligomers led to an interaction parameter χ value of 4.3 at 150°C which is 6 times greater than PS-b-PDHS, one of the highest reported value for BCPs.…”