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

Highly Ordered Gyroid Nanostructured Polymers: Facile Fabrication by Polymerizable Pluronic Surfactants

Highly ordered, network-nanostructured polymers offer compelling geometric features and application potential. However, their practical utilization is hampered by the restricted accessibility. Here, we address this challenge using commercial Pluronic surfactants with a straightforward modification of tethering polymerizable groups. By leveraging lyotropic self-assembly, we achieve facile production of double-gyroid mesophases, which are subsequently solidified via photoinduced cross-linking. The exceptionally ordered periodicities of Ia3d symmetry in the photocured polymers are unambiguously confirmed by synchrotron small-angle X-ray scattering (SAXS), which can capture single-crystal-like diffraction patterns. Electron density maps reconstructed from SAXS data complemented by transmission electron microscopy analysis further elucidate the real-space gyroid assemblies. Intriguingly, by tuning the cross-linking through thiol-acrylate chemistry, the mechanical properties of the polymer are modulated without compromising the integrity of Ia3d assemblies. The 3-D percolating gyroid nanochannels demonstrate an ionic conductivity that surpasses that of disordered structures, offering promising prospects for scalable fabrication.

Self-Assembly of Unusually Stable Thermotropic Network Phases by Cellobiose-Based Guerbet Glycolipids

Bicontinuous thermotropic liquid crystal (LC) materials, e.g., double gyroid (DG) phases, have garnered significant attention due to the potential utility of their 3D network structures in wide-ranging applications. However, the utility of these materials is significantly constrained by the lack of robust molecular design rules for shape-filling amphiphiles that spontaneously adopt the saddle curvatures required to access these useful supramolecular assemblies. Toward this aim, we synthesized anomerically pure Guerbet-type glycolipids bearing cellobiose head groups and branched alkyl tails and studied their thermotropic LC self-assembly. Using a combination of differential scanning calorimetry, polarized optical microscopy, and small-angle X-ray scattering, our studies demonstrate that Guerbet cellobiosides exhibit a strong propensity to self-assemble into DG morphologies over wide thermotropic phase windows. The stabilities of these assemblies sensitively depend on the branched alkyl tail structure and the anomeric configuration of the glycolipid in a previously unrecognized manner. Complementary molecular simulations furnish detailed insights into the observed self-assembly characteristics, thus unveiling molecular motifs that foster network phase self-assembly that will enable future designs and applications of network LC materials.

Stabilizing Differential Interfacial Curvatures by Mismatched Molecular Geometries: Toward Polymers with Percolating 1 nm Channels of Gyroid Minimal Surfaces

Soft materials with self-assembled networks possess saddle-shaped interfaces with distributed negative Gaussian curvatures. The ability to stabilize such a geometry is critically important for various applications but can be challenging due to the possibly "deficient" packing of the building blocks. This nontrivial challenge has been manifested, for example, by the limited availability of cross-linkable bicontinuous cubic (Q) liquid crystals (LCs), which can be utilized to fabricate compelling polymers with networked nanochannels uniformly sized at ∼1 nm. Here, we devise a facile approach to stabilizing cross-linkable Q mesophases by leveraging the synergistic self-assembly from pairs of scalably synthesized polymerizable amphiphiles. Hybridization of the molecular geometries by mixing significantly increases the propensity of the local deviations in the interfacial curvature specifically required for Q assemblies. "Normal" (type 1) double gyroid LCs possessing 1 nm ionic channels conforming to minimal surfaces can be formulated by simultaneous hydration of the amphiphile mixtures, as opposed to the formation of hexagonal or lamellar mesophases exhibited by the single-amphiphile systems, respectively. Fixation of the bicontinuous network in polymers via radical polymerization has been efficaciously facilitated by the presence of the bifunctional polymerizable groups in one of the employed amphiphiles. High-fidelity lock-in of the ordered continuous 1 nm channels has been unambiguously confirmed by the observation of single-crystal-like diffraction patterns from synchrotron small-angle X-ray scattering and large-area periodicities by transmission electron microscopy. The produced polymeric materials exhibit the required mechanical integrity as well as chemical robustness in a variety of organic solvents that benefit their practical applications for selective transport of ions and molecules.

Temporal Control over Two- and Three-State Living Coordinative Chain Transfer Polymerization for Modulating the Molecular Weight Distribution Profile of Polyolefins

A highly versatile new strategy for manipulating the molecular weight profiles, including breadth, asymmetry (skewness) and modal nature (mono-, bi-, and multimodal), of a variety of different polyolefins is reported. It involves temporal control over two- and three-state living coordinative chain transfer polymerization (LCCTP) of olefins in a programmable way. By changing the identity of the R' groups of the chain transfer agent, ER'_n , with time, different populations of chains within a bi- or multimodal polyolefin product can be selectively tagged with different end-groups. By changing the nature of the main-group metal of the CTA, programmed manipulation of the relative magnitudes of the dispersities of the different maxima that make up the final MWD profile can be achieved. This strategy can be implemented with existing LCCTP materials and conventional reactor methods to provide access to scalable and practical quantities of an unlimited array of new polyolefin materials.