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

Abstract

Discrete block co-oligomers (BCOs) are gaining considerable attention due to their potential to form highly ordered ultrasmall nanostructures suitable for lithographic templates. However, laborious synthetic routes present a major hurdle to the practical application. Herein, we report a readily available discrete BCO system that is capable of forming various self-assembled nanostructures with ultrasmall periodicity. Click coupling of propargyl-functionalized sugars (containing 1–7 glucose units) and azido-functionalized terpenoids (containing 3, 4, and 9 isoprene units) afforded the discrete and monodisperse BCOs with a desired total degree of polymerization and block ratio. These BCOs microphase separated into lamellar, gyroid, and cylindrical morphologies with the domain spacing (d) of 4.2–7.5 nm. Considering easy synthesis and rich phase behavior, presented BCO systems could be highly promising for application to diverse ~4-nm nanofabrications.

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

“…GYR is typically formed from BCPs with a volume fraction of 0.35–0.39, but Glc 1 - b -DMS n - b -Glc 1 lies outside this range (saccharide volume fraction is around 0.18). 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 ].…”

“…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 .…”

Enhanced Self-Assembly and Mechanical Properties of Cellulose-Based Triblock Copolymers: Comparisons with Amylose-Based Triblock Copolymers

“…An alternative pathway for producing carbohydrate BCPs involves the end-to-end coupling of end-functionalized carbohydrates and synthetic polymer segments, to which various synthetic polymer segments can be joined. 11,12,[17][18][19]26 In particular, the copper-catalyzed azido-alkyne cycloaddition (CuAAC) reaction has been widely employed for end-to-end coupling because of its high efficiency, simplicity, and functional group tolerance. 32−34 Most carbohydrate-based BCPs comprise dextran and amylose.…”