Stable Thermotropic 3D and 2D Double Gyroid Nanostructures with Sub‐2‐nm Feature Size from Scalable Sugar–Polyolefin Conjugates

Abstract

Ultra-low molecular weight disaccharide-polyolefin conjugates with cellobiose, lactose and maltose head groups and atactic polypropene tails, such as 1, undergo a series of irreversible thermotropic order-order transitions with increasing temperature to provide nanostructured phases in the sequence: lamellar (L), hexagonal perforated lamellar (HPL), double gyroid (DG) and hexagonal cylindrical (C). The DG phase displays exceptional stability at ambient temperature and features two interpenetrating sugar domain networks having a sub-2-nm strut width and a lattice parameter, a DG , of 13.1 nm. The unique stability of this DG phase extends further within ultrathin films all the way down to the two-dimensional limit of 15 nm in which film thickness, l, is now less than the surface-oriented unit cell height, h DG . In addition to raising the fundamental question of what minimally constitutes a Schoen triply periodic minimal surface and DG lattice, these results serve to establish the class of sugarpolyolefin conjugates as a new material platform for nanoscience and nanotechnology.Scheme 1. Structures of sugar-polyolefin conjugates 1-5.

Fabrication of Ultrafine, Highly Ordered Nanostructures Using Carbohydrate-Inorganic Hybrid Block Copolymers

“…However, our previous study [ 37 ] demonstrated that when a saccharide volume fraction of 0.21–0.25 occurs, discrete BCPs composed of oligosaccharide and terpenoid blocks self-assembled into GYR. Additionally, Sita’s group [ 36 ] demonstrated that BCPs containing atactic polypropylene and cellobiose with a saccharide volume fraction of 0.23 formed GYR structures, which is consistent with our previous work [ 37 ]. Thus, the glucose block’s rigidity and strong intermolecular interaction may play a significant role in the formation of unusual GYR.…”

“…To overcome this constraint, the enhancement of χ is required, and indeed, numerous research groups have demonstrated microphase-separation from so-called “high χ /low N ” BCPs, resulting in ordered morphologies with d of less than 10 nm. Thus far, silicon-containing [ 3 , 5 , 6 , 7 , 10 , 12 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], metal-doped [ 31 , 32 , 33 ], and oligosaccharide-based BCPs [ 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 ] have been developed. The high χ /low N BCP strategy is now widely accepted as a standard method for obtaining smaller d , although several novel approaches have emerged recently [ 19 , 34 , 35 , 40 , 49 ,…”

“…More precisely, we used maltooligosaccharides as the carbohydrate building block because maltooligosaccharides with a discrete number of glucose repeating units are readily available, allowing for the precise control of the volume fraction and, consequently, the resulting morphology. Indeed, our research group [ 37 ] and Sita’s research group [ 36 ] independently reported a variety of microphase-separated nanostructures derived from oligosaccharide-based organic BCPs by varying glucose unit counts. The molecular structures and synthetic route for the target ultrahigh χ /low N organic–inorganic hybrid triblock copolymers (Glc m - b -DMS n - b -Glc m ; m = 1–3), which are composed of maltooligosaccharides (glucose, Glc 1 ; maltose, Glc 2 ; maltotriose, Glc 3 ) and oligodimethylsiloxane ( o DMS), are shown in Scheme 1 .…”

Ordered Nanostructures in Thin Films of Precise Ion-Containing Multiblock Copolymers

“… 46 − 48 Recently, a disaccharide–atactic polypropylene conjugate showed double gyroids ( a gyr = 13.1 nm) in thin films (15–150 nm) on carbon-coated silicon substrates, suggesting hydrogen-bonding interaction of saccharides is a crucial factor in determining the morphology. 49 Here, we demonstrate that a precise ion-containing multiblock copolymer self-assembles into highly oriented double gyroids with a smaller lattice parameter of 6.1 nm in thin films (≥26 nm). We attribute these double-gyroid morphologies in thin films to (1) the precisely alternating (AB) n multiblock architecture with perfectly monodisperse block length and (2) the large interaction parameter between the blocks that drive microphase separation via ionic functionalities.…”

Stabilizing a Double Gyroid Network Phase with 2 nm Feature Size by Blending of Lamellar and Cylindrical Forming Block Oligomers

“… 28 − 37 For example, NET phases with sub-5 nm domain spacing are observed in glycolipids and T-shaped liquid crystals. 38 − 42 In our previous simulation and experimental studies, a series of block oligomers containing sugar-based (A) and hydrocarbon-based (B) blocks were found to self-assemble into ordered thermotropic phases including LAM, perforated lamellae (PL), and CYL with domain periods as small as 1.2 nm, 43 − 45 and good agreement is observed for the domain spacing with experimental data. 44 , 46 …”