Consequences of Molecular Architecture on the Supramolecular Assembly of Discrete Block Co-oligomers

Abstract

Supramolecular block copolymers composed of discrete blocks have promising properties for nanotechnology resulting from their ability to combine well-defined morphologies with good bulk material properties. Here, we present the impact of a well-defined siloxane block in either the main-chain or present as pendant grafts on the properties of supramolecular block copolymers that form ordered nanostructures with sub-5 nm domains. For this, two types of supramolecular block copolymers were synthesized based on the ureidopyrimidinone–urethane (UPy-UT) motif. In the first, oligodimethyl­siloxanes (oDMS) of discrete length were end-capped with the UPy-UT motif, affording main-chain UPy-UT-Si n . In the second, the UPy-UT motif was grafted with discrete oDMS affording grafted UPy-UT- g -Si 7 . For the two systems, the compositions are similar; only the molecular architecture differs. In both cases, crystallization of the UPy-UT block is in synergy with phase segregation of the oDMS, resulting in the formation of lamellar morphologies. The grafted UPy-UT- g -Si 7 can form long-range ordered lamellae, resulting in the formation of micrometer-sized 2D sheets of supramolecular polymers which show brittle properties. In contrast, UPy-UT-Si n forms a ductile material. As the compositions of both BCOs are similar, the differences in morphology and mechanical properties are a direct consequence of the molecular architecture. These results showcase how molecular design of the building block capable of forming block copolymers translates into controlled nanostructures and material properties as a result of the supramolecular nature of the interactions.

Room-Temperature Solid-State UV Cross-Linkable Vitrimer-like Polymers for Additive Manufacturing

“…This is similar to the cross-linked polybutadiene reported in [ 22 ], in which the quadruple hydrogen-bonding interactions of UPy play the same role as chemical cross-linking in the polybutadiene chains. When compared with other UPy-functionalized polymers, [ 9 , 11 ] it appears that the relatively lower strain observed here is mostly due to the structure of HTPB itself.…”

“…Hence, a polymer with UPy groups has interesting functions, such as the shape memory effect and self-healing [ 7 , 8 , 9 , 10 ]. Due to the strong quadruple hydrogen bonding of UPy, oligomers can be assembled into supramolecular polymers, which are ductile [ 11 , 12 ]. The formation and breakage of the quadruple hydrogen bonds are affected by the temperature and right solvent [ 13 , 14 ].…”

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

“…However, the majority of organic–inorganic hybrid BCPs formed a microphase-separated structure with a d of at least 10 nm. Vantomme’s group [ 14 ] previously reported an organic–inorganic hybrid BCP that formed a microphase-separated structure with a d of 3.5 nm, but only the lamellar structure was observed. As a result, fabricating various nanostructures with a 5 nm scale periodicity remains a significant challenge for applications in nanotechnology, such as next-generation lithography, and the synthesis of a novel BCP capable of achieving microphase-separated structures with a d of around 5 nm or less is desired.…”

“…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 ,…”

“…Despite having a molecular weight of less than 2500, Glc m - b -DMS n - b -Glc m self-assembled into highly ordered lamellar and gyroid morphologies in the bulk and thin film states. Owing to the ultrahigh χ /low N nature of the material and the ABA-type architecture, a d of as little as 5 nm was achieved, which is among the smallest in microphase-separated organic–inorganic hybrid BCPs [ 14 , 25 , 29 , 30 ].…”