Macroscopically anisotropic supramolecular materials prepared from an undercooled liquid-crystalline phase of a cholesterol-based low-molecular-weight compound

Abstract

Supramolecular bulk materials composed of low-molecular-weight compounds offer a promising pathway toward sustainable materials. However, achieving a macroscopic structural order and tuneable mechanical properties without relying on covalently bonded macromolecular components remains a significant challenge. We develop a supramolecular material derived from a cholesterol-based low-molecular-weight compound, (3β)-cholest-5-en-3-yl dodecylcarbamate, that forms a metastable liquid-crystalline (LC) phase upon quenching from its isotropic melt. The LC phase displays sufficient fluidity at room temperature to permit bulk processing, for example, by compression; the material subsequently undergoes spontaneous crystallization to form a self-standing sheet. By controlling the quenching temperature and the incubation time prior to processing, we succeed in endowing the sheet with molecular ordering that extends beyond the centimetre scale and, as a result, the sheet exhibits anisotropic mechanical properties. These findings establish a design strategy for creating processable, structurally tuneable, bulk materials exclusively from small molecules.

Supramolecular bulk materials formed by low-molecular-weight systems offer a promising sustainability solution, but achieving order and tuneable properties is challenging. Here the authors develop a supramolecular cholesterol-based material that forms a metastable liquid crystalline phase upon quenching from its isotropic melt.

Introduction

Polymeric materials are indispensable to modern society; however, in the light of growing environmental concerns, even a partial replacement of widely used polymers by renewable alternatives has become imperative^1–4. Among emerging candidates, supramolecular polymers offer unique structural and functional advantages due to the reversibility of their noncovalent bonding^5–8, making them attractive for the design of sustainable and recyclable materials. It should be noted, however, that many polymeric systems based on supramolecular chemistry remain reliant on covalently bonded polymers (i.e., macromolecules) as key components^9–17. In this work, we shift the focus to bulk materials that are composed exclusively of low-molecular-weight compounds^18–33.

In 2008, Leibler and co-workers¹⁸ reported a self-healing rubber that harnessed the dynamic and reversible nature of noncovalent bonds. Although the molar mass (M) of the material could not be defined due to its composition as a mixture of small molecules, the study marked a seminal advance in the design of supramolecular bulk materials. In 2016, Weder and co-workers¹⁹ developed supramolecular glasses consisting of a 2-ureidopyrimidin-4-one derivative (M = 1014 g/mol) that exhibited high stiffness (flexural modulus = 3.04 ± 0.26 GPa) and light-induced self-healing capabilities. More recently, the groups of Yan²⁰ and Gazit²¹ independently reported naturally occurring peptide-based molecular glasses (M = 503 and 507 g/mol, respectively) that displayed transparency, rigidity, and biodegradability. In parallel, Aida and co-workers²² introduced a new class of ionic supramolecular bulk materials formed through liquid–liquid phase separation of low-molecular-weight ionic compounds (M = 216 and 474 g/mol for cationic and anionic species, respectively). Remarkably, these ionic supramolecular materials remained stable under ambient conditions but underwent degradation and metabolic conversion under biologically relevant conditions. Collectively, these pioneering studies underscore the versatility and promise of low-molecular-weight compounds as building blocks for the development of sustainable materials.

What, then, distinguishes a macromolecule? Insights from macromolecular systems suggest that the construction of a hierarchically organized structure is a promising pathway toward enhanced material properties^34–40. A particularly attractive feature is the ability to control the higher-order structure of materials by applying varied processing conditions, while based on identical primary structures. This, in turn, permits tailoring of material properties, a capability that is highly valued in materials science. Representative examples include liquid-crystalline (LC) spinning of aramid fibres^35,36 and the flow-induced formation of shish-kebab structures^37,38. Reflecting on these examples, it should be noted that the abovementioned supramolecular materials are inherently amorphous, exhibiting characteristics of rubbers and glasses, and lack long-range molecular order or a hierarchical structure.

Here, we report the fabrication of macroscopically anisotropic self-standing sheets and filaments derived from a cholesterol-based low-molecular-weight compound, (3β)-cholest-5-en-3-yl dodecylcarbamate (M = 598 g/mol). This derivative formed a metastable LC phase with sufficient fluidity to permit facile processing. Notably, the processing conditions critically influenced the molecular alignment within the supramolecular sheets, thereby giving rise to distinct mechanical properties. Previous studies by the groups of Würthner³¹ and Ortony³² and by our own groups³³ have demonstrated the formation of anisotropic supramolecular threads by means of solution-based techniques such as electrospinning and manual drawing. However, the resulting material properties were governed primarily by the molecular design. In contrast, the present work highlights the pivotal role of the processing protocol itself in dictating supramolecular architecture and material properties, illustrating a conceptual parallel with macromolecule-based materials^39,40.

Results

Cholesterol derivatives, identified in the late nineteenth century, represent the earliest known compounds to present an LC behaviour⁴¹. In recent decades, cholesteryl moieties have been widely employed as self-assembling units in the field of supramolecular chemistry^42–44. Motivated by this precedent, we designed a cholesterol-based molecular building block with the aim of producing a supramolecular material that would exhibit a macroscopic molecular order.

To this end, alkyl chains of varying lengths were introduced via a carbamate linkage that would serve to stabilize the ordered structure through hydrogen bonding (Fig. 1). The derivatives (3β)-cholest-5-en-3-yl hexylcarbamate (Chol-C₆), (3β)-cholest-5-en-3-yl dodecylcarbamate (Chol-C₁₂), and (3β)-cholest-5-en-3-yl octadecylcarbamate (Chol-C₁₈) were obtained in good yields (~95%) by a one-step reaction starting from a commercially available cholesterol chloroformate and the corresponding amines. Notably, single 10 g batches of the analytically pure compounds were readily obtainable without column chromatography purification.

Fig. 1.

Chemical structures of cholesterol derivatives used in this study: n = 6, 12, or 18.

Characterization of the supramolecular materials

We first assessed the thermal properties of the three cholesterol derivatives by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and polarized optical microscopy (POM). Chol-C₆, Chol-C₁₂, and Chol-C₁₈ each underwent a 2% weight loss at adequately higher temperatures of 269, 276, and 277 °C, respectively (Supplementary Fig. 7), and their melting points (T_m) were 87, 78, and 81 °C, respectively. Figure 2a shows the DSC traces of the cholesterol derivatives, excluding the first heating scan and displaying data from the first cooling scan and the second heating scan (10 °C/min). Below their melting points, the compounds displayed multiple peaks, indicating the presence of mesophases. Upon cooling from its isotropic melt, Chol-C₆ formed an LC phase in the temperature range from 86 to 3 °C, as confirmed by the observation of a characteristic texture under crossed Nicols (Supplementary Fig. 8). Chol-C₁₈ displayed multiple phase transitions, probably as a result of the complex interplay between the cholesteryl and octadecyl moieties within the LC phases. Intriguingly, the thermal behaviour of Chol-C₁₂ was found to involve an undercooled state. Specifically, cooling Chol-C₁₂ from its isotropic melt led to the formation of an LC phase (Supplementary Fig. 9) that subsequently underwent vitrification, as indicated by a glass transition at −1 °C (T_g). Upon reheating above the T_g (second heating), the sample exhibited an exothermic cold crystallization at 36 °C (ΔH = − 13.58 kJ mol⁻¹), followed by an endothermic transition to the LC phase (T_c = 46 °C, ΔH = +12.95 kJ mol⁻¹). Further heating resulted in an isotropic melt (T_m = 78 °C, ΔH = +0.89 kJ mol⁻¹). These DSC curves indicate that Chol-C₁₂ forms a metastable LC phase at room temperature. It should be noted that such a metastable LC phase of cholesterol derivatives has been known for a long time⁴⁵; we sought to exploit this metastable state to produce a new type of supramolecular bulk material.

Fig. 2. Phase transition of the cholesterol derivatives.

a DSC curves of the cholesterol derivatives (10 °C/min). b, c Changes in the XRD profiles (b) and FT-IR spectra (c) of Chol-C₁₂ during a first cooling from 100 to −10 °C followed by a second heating to 100 °C. d Gibbs energy landscape of Chol-C₁₂ in which x axis qualitatively represents structural parameters associated with the degree of molecular organization in the solid state; upon quenching from its isotropic melt, Chol-C₁₂ forms a metastable smectic phase, which transforms into crystalline lamellae structure over time. Smectic layers appear to be helically rotated with a pitch of several hundred nanometres (Supplementary Fig. 19), far exceeding the layer spacing. Such a long-pitch helical structure cannot be represented in 2 d, and a complete structural characterization of the LC phase lies beyond the scope of the present study.

Before doing so, we investigated the changes in the molecular packing of Chol-C₁₂ during its thermal phase transition by means of temperature-dependent X-ray diffraction (XRD) measurements and Fourier-transform infrared (FT-IR) spectroscopy. At 100 °C, Chol-C₁₂ is an isotropic liquid, as confirmed by the absence of birefringence in POM observations (Supplementary Fig. 9). Upon cooling to approximately 50 °C, a prominent diffraction peak appeared at 2θ = 2.66 (d-spacings of 3.32 nm), indicating the formation of a smectic phase (Fig. 2b). This phase transition was accompanied by the enhancement of hydrogen bonds, as evidenced by a shift in the N − H stretching vibration band from 3364 to 3340 cm⁻¹, down to –10 °C (Fig. 2c). Upon reheating, cold crystallization at around 40 °C induced a weakening of the hydrogen bonds; the N − H band shifted from 3340 to 3375 cm⁻¹, probably caused by enhanced packing of the cholesteryl moieties upon crystallization. In the crystallized form, diffraction peaks at 2θ = 1.78, 3.46, and 5.28 were observed: the ratio of these 2θ values (1:2:3) indicated the formation of crystalline lamellar structures consisting of bilayers of Chol-C₁₂ (d-spacings of 4.96 nm). The absence of both the amorphous halo and the smectic peak (Fig. 2b, cyan line) indicates that the material is fully crystallized. A shift of the methylene asymmetric stretching band toward a lower wavenumber (from 2925 to 2919 cm⁻¹) also suggested that crystalline lamellae were formed (Supplementary Fig. 10)⁴⁶. Collectively, the molecular packing of Chol-C₁₂ in the smectic LC and crystalline lamellae and the corresponding energy landscape can be depicted as shown in Fig. 2d. The same experiments were also conducted for Chol-C₆ and Chol-C₁₈, but these derivatives will not be discussed further in this manuscript (Supplementary Figs. 11 and 12).

The cold crystallization of Chol-C₁₂ was facilitated when it had been deeply quenched from the isotropic melt to temperatures below 10 °C, as observed by DSC measurements (Supplementary Fig. 13). In contrast, the metastable LC phase obtained by shallow quenching to the room temperature (25 °C), showed sluggish crystallization kinetics (~3 hours), as revealed by time-dependent XRD measurements (Supplementary Fig. 14c). These results suggest that nucleation of the crystalline lamellae is facilitated between the T_g (−1 °C) and ca. 10 °C. To further elucidate the cold crystallization behaviour, isothermal DSC measurements were performed. Chol-C₁₂ was isotropically melted (100 °C) and subsequently quenched to −50 °C within the sample chamber of the calorimeter, thereby arresting the LC phase. The sample was then warmed (50 °C/min) and kept at various temperatures above the T_g to promote nucleation while the exothermic response was continuously monitored over time (Supplementary Fig. 15). Crystallization completed within 10 min at about 30 °C, and Avrami plots suggested the occurrence of homogeneous nucleation and three-dimensional crystal growth (Avrami constant ≈4.0; Supplementary Fig. 16b). In fact, we observed the formation of spherulites under POM (Supplementary Fig. 17b).

Like other supramolecular rubbers and glasses^18–22,28, Chol-C₁₂ was mouldable from its isotropic melt to form a crystalline bulk solid; to complete the crystallization, the material was removed from the mould after one day (Fig. 3a, see Supplementary Information: melt-moulding method). The compression force and flexural force of the resulting material, evaluated by a compression test and a three-point bending test, were 97 N and 236 N, respectively (Figs. 3b, c). The flexural modulus of the Chol-C₁₂ solid (E_f = 194 MPa) was comparable to that of low-density polyethylene (LDPE) (E_f = 87 MPa, measured under the same condition). Although these values are lower than those of supramolecular glasses¹⁹, probably due to a lower density of hydrogen-bonding moieties, the Chol-C₁₂ solid showed properties distinct from those of other solids consisting of small molecules, such as soaps (amphiphiles) or candle wax (alkanes). To our surprise, a single piece of the material (5.0 g) withstood 2000 times its own weight (10 kg) (Fig. 3d).

Fig. 3. Chol-C₁₂ solid.

a Macroscopic appearance of a Chol-C₁₂ solid obtained by melt moulding. b, c Compression test (b) and three-point flexural test (c) conducted for the Chol-C₁₂ solid. Results of LDPE, candle wax, and soap are shown for comparison. Compression tests were conducted using a spherical jig with a diameter of 3 mm. Flexural tests were conducted with a bending span of 20 mm. d Chol-C₁₂ solid (L 39 × W 19 × H 7 mm; 5.0 g) withstanding 2000 times its own weight (10 kg).

Processing of supramolecular bulk material

The metastable smectic LC phase of Chol-C₁₂ retained an adequate degree of fluidity at room temperature for a sufficient time to render it amenable to processing (viscosity = ~10⁶ mPa·s; Supplementary Fig. 18). To produce the bulk material, 2.0 g of Chol-C₁₂ were melted at 100 °C in a silicone mould and then quenched on an aluminium block cooled in a liquid-nitrogen bath (Fig. 4a). This procedure resulted in a translucent sample of Chol-C₁₂ in its metastable LC phase with a diameter of 30 mm and a thickness of approximately 2.5 mm. This sample was then sandwiched between sheets of poly(ethylene terephthalate) (PET) and compressed under a load of 98 kN for 10 s at room temperature. Remarkably, the resulting material displayed a brilliant blue hue (Fig. 4b). Circular dichroism (CD) spectroscopic measurements confirmed that this blue colour originates from selective reflection by a helically twisted smectic structure, rather than from light scattering (e.g., Rayleigh scattering due to nuclei formation) (Supplementary Fig. 19). As the crystallization progressed, the blue colour of the compressed sheet gradually diminished over 10 min (Fig. 4c and Supplementary Fig. 20), yielding a self-standing circular sheet 130 mm in diameter with a thickness of approximately 170 µm. The parent cholesterol, liquid-crystalline cholesteryl oleyl carbonate, and a simple mixture of these two compounds all failed to yield such a self-standing flexible material through a (hot-)pressing technique (Supplementary Fig. 21). We inferred, therefore, that the liquid crystalline nature, along with its intermolecular hydrogen bonding^47,48, resulted in the crystalline self-standing material.

Fig. 4. Processing of the supramolecular bulk material.

a Metastable LC sample obtained by quenching an isotropic melt of Chol-C₁₂ in a silicone mould. b, c Macroscopic appearances of the materials immediately after pressing (b) and subsequent aging (c). d, e, i, j 2D XRD images of sheet-0 (d, e) and sheet-4 (i, j) obtained immediately after pressing (t_age = 1 min: d, i) and after subsequent aging (t_age = 30 min: e, j), upon exposure to an X-ray beam from the direction perpendicular to the sheet. The arrows indicate the radial direction of material flow caused by the pressing process. g, l Changes in the XRD profiles observed during the aging process for sheet-0 (g) and sheet-4 (l). f, k Appearances of the obtained sheet-0 (f) and sheet-4 (k) under crossed Nicols. h, m Angle dependences of the absorbance of hydrogen-bonded N-H stretching vibration band (3375 cm^–1) with respect to the radial axis, measured for sheet-0 (h) and sheet-4 (m). n Schematic illustration of the molecular ordering of Chol-C₁₂ within sheet-4, shown together with 2D XRD images obtained upon exposure to an X-ray beam from the directions perpendicular (i) and parallel ((ii) radial axis and (iii) tangential axis) to the sheet.

It is noteworthy that the crystallization kinetics (~10 min: Supplementary Figs. 14 and 15) are comparable to the time required for sheet processing (a few minutes). Accordingly, we hypothesized that the duration prior to pressing the undercooled LC phase, herein defined as the incubation time (t_inc), would be a critical parameter in determining the structural and physical properties of the resulting sheet (see, Fig. 4a). We therefore fabricated sheets of Chol-C₁₂ with various t_inc intervals: hereafter, these sheets are referred to as “sheet-t_inc”, where t_inc is the incubation time in minutes. Although no significant differences were observed in the visual appearance of the resulting sheets under room light (Supplementary Fig. 22), sheet-4 showed a markedly different birefringence property to the other sheets, such as sheet-0, under crossed Nicols (Fig. 4f, k for sheet-0 and sheet-4, respectively). The observed pattern reminiscent of Maltese cross suggested that the material flow upon compression had induced a macroscopic radial alignment of the crystalline lamellae within sheet-4 (Fig. 4k).

To gain a deeper insight into the influence of t_inc, the sheets prepared with different t_inc intervals were subjected to time-dependent XRD measurement immediately after pressing (Fig. 4g, l). The peak intensity was normalized based on the result of sheet-0. As the sheets aged over several tens of minutes (t_age), the intensity of the peak corresponding to the smectic phase diminished while distinct peaks associated with crystalline lamellae emerged (Fig. 4g), indicating a phase transformation and progressive crystallization over time. Interestingly, during the formation of sheet-4, both smectic and lamellar diffractions appeared as equatorial concentric arcs in the 2D XRD image with respect to the radial axis of the circular sheet (Fig. 4i); the order parameters (S) for these two phases (smectic and lamellar) calculated based on the 2D XRD pattern were 0.38 and 0.33, respectively (t_inc = 4 min, t_age = 1 min). On the other hand, such anisotropic patterns were absent for sheet-0 (Fig. 4d, e) or only faintly visible for other sheets prepared with shorter t_inc intervals (sheet-1, -2, and -3; Supplementary Fig. 23). Thus, the smectic LC alone does not undergo macroscopic orientation upon compression (t_inc = 0 min, t_age = 1 min; S = 0.02). These observations indicate that the smectic and lamellar layers cooperatively aligned, provided that a substantial degree of crystallization had been attained during the incubation period prior to pressing. Further crystallization then immobilized the anisotropic alignment (t_inc = 4 min, t_age = 30 min: that is, sheet-4; S = 0.42, Fig. 4j). It should be noted that longer t_inc intervals (ca. 10 min) lead to higher crystallinity and deteriorate the processability, such that alignment is no longer achievable (Supplementary Fig. 24). In addition, liquid nitrogen quenching is crucial in the processing (Fig. 4a); otherwise, nucleation occurs sporadically, and crystallization proceeds so slowly that the alignment induced by compression undergoes relaxation before being immobilized (Supplementary Fig. 25). Collectively, these observations indicate that with the optimal quenching temperature and the incubation time, macroscopic alignment extending over the centimetre-scale is achievable in a self-standing crystalline sheet consisting exclusively of a low-molecular-weight compound (Supplementary Fig. 26).

The radial alignment suggested by the Maltese cross pattern (Fig. 4k) was corroborated by mapping 2D XRD images at 35 positions (7 × 5 grid) near the centre of sheet-4 (Supplementary Fig. 27). In addition to the direction normal to the sheet plane (Fig. 4j, 4n(i)), XRD measurements were conducted toward cross-sections of sheet-4 (Fig. 4n). The 2D XRD image obtained across the radial axis revealed the periodicity of the lamellae, appearing as equatorial concentric arcs relative to the normal of the circular sheet (Fig. 4n(ii)). In contrast, for the tangential axis, the diffraction by the lamellae was only faintly observed (Fig. 4n(iii)). Furthermore, polarized FT-IR spectroscopy revealed that the hydrogen bonding array was aligned along the radial axis in sheet-4 (Fig. 4h, m). On the basis of these results, the molecular orientation within the crystalline lamellae is depicted as shown in Fig. 4n.

Reflecting its macroscopic molecular ordering, circular sheet-4 exhibited unique mechanical properties. Specifically, it was prone to fracture along the radial axis (Fig. 5b), resulting in wedge-shaped fragments. Bending the fragment in the direction of the tangential axis gave rise to fracture with a distinct cracking sound (Supplementary Movie 1), indicative of the release of internal mechanical stress associated with a brittle-failure behaviour of the material. In contrast, the fragment showed elasticity in the radial direction (Fig. 5c and Supplementary Movie 2). Such angle-dependent fracture behaviour was absent in other sheets, such as sheet-0 (Fig. 5a). These results establish a new class of supramolecular bulk material formed exclusively from a low-molecular-weight compound and exhibiting pronounced anisotropic mechanical properties.

Fig. 5. Mechanical properties of supramolecular bulk materials.

a–c Macroscopic appearances of sheet-0 (a) and sheet-4 (b, c). Sheet-4 is prone to radial fracture (c, top), and the resulting wedge-shaped fragment showed elasticity in the radial direction (c, bottom). See also Supplementary Movies 1 and 2. d Stress–strain curves of sheet-0 and sheet-4 (20 mm × 2 mm × c.a. 170 µm). e–h Comparison of the mechanical properties of sheet-0 and sheet-4 in terms of the Young’s modulus (e), ultimate strength (f), elongation at break (g), and toughness (h): The error bars represent 95% confidence intervals; n = 5.

Tensile tests were conducted for sheet-0 and sheet-4 along the radial direction (1 mm/min; Fig. 5d). The Young’s moduli and ultimate strengths of sheet-0 were 220 ± 54 MPa and 2.8 ± 1.0 MPa, respectively, whereas those of sheet-4 were 271 ± 57 MPa and 3.7 ± 0.3 MPa (Fig. 5e, f and Supplementary Fig. 28, n = 5). Remarkably, sheet-4 exhibited tensile extensibility (elongation at break: 7.9 ± 1.0%, Fig. 5g), which likely originates from sliding of the aligned lamellae. The lower extensibility of sheet-0 is attributable to sample heterogeneity or random orientation of the lamellae. Consequently, sheet-4 shows a toughness approximately one order of magnitude higher than that of sheet-0 (24.8 ± 2.4 MJ m⁻³ and 2.6 ± 1.9 MJ m⁻³, respectively: Fig. 5h). These findings demonstrate that an appropriate choice of the processing protocol permits precise control over the higher-order structures of Chol-C₁₂, which directly influences the mechanical properties of the resulting material. Unlike other supramolecular bulk materials that are dominated by hydrogen bonding^18,21,22, the mechanical properties of Chol-C₁₂ exhibited negligible susceptibility to environmental moisture due to the hydrophobic nature of the cholesterol moiety (Supplementary Fig. 29). Moreover, the material demonstrated thermal reshaping capabilities akin to those of thermoplastics, and it could be readily dissolved in organic solvents to recover chemically pure monomeric Chol-C₁₂, as verified by ¹H NMR spectroscopy (Supplementary Fig. 30). The recovered Chol-C₁₂ was processable repeatedly by the method shown in Fig. 4a. These features indicate the potential recyclability of Chol-C₁₂-based supramolecular bulk materials.

The metastable LC phase remains frozen in a state of “hibernation” as long as it is kept below its T_g. Once the temperature is raised above the T_g, the LC phase exits its dormant state, and crystallization begins (Supplementary Fig. 31). By using appropriate techniques, the metastable LC can be processed into various forms. For example, by extrusion at room temperature, we successfully fabricated a filament with a diameter of 1 mm and a length of over 1 m (Fig. 6a, b) in which crystalline lamellae of Chol-C₁₂ were unidirectionally aligned along the filament (Fig. 6c, d). The Young’s modulus of this filament was 550 ± 208 MPa (Supplementary Fig. 32), a value higher than that of sheet-4 (271 ± 57 MPa, Fig. 5d) and parallel with that of a thread composed of an aramid amphiphile (637 ± 114 MPa) reported by Ortony³¹, probably due to the better molecular ordering (S = 0.64: Fig. 6c, d). Interestingly, the filament exhibited a propensity to fracture longitudinally along its axis when stress was applied, reminiscent of the splitting behaviour of bamboo (Fig. 6b).

Fig. 6. Supramolecular filament prepared by extrusion.

a A filament of Chol-C₁₂ prepared by extrusion of a metastable smectic LC state at room temperature. b Appearance of the filament fractured longitudinally along its axis. c, d 2D XRD image observed upon exposure to an X-ray beam from the direction parallel (c) and perpendicular (d) to the long axis of the filament.

Discussion

In this study, we demonstrated the fabrication of a supramolecular bulk material derived exclusively from a low-molecular-weight compound, Chol-C₁₂ (M = 598 g/mol). By exploiting its metastable LC phase prepared from its isotropic melt, we achieved macroscopic molecular alignment through kinetically controlled processing, resulting in a self-standing crystalline sheet with anisotropic mechanical properties. Systematic investigation revealed that the quenching temperature and the incubation time prior to compression plays a critical role in dictating the degree of molecular ordering and the properties of the resulting material. We expect that the present approach, established by combining the kinetic behaviour and the processing conditions, is applicable not only to cholesterol derivatives but also to diverse molecules that crystallize through an undercooled liquid-crystalline phase.

The ability to induce molecular ordering extending beyond a centimetre scale, along with anisotropic mechanical behaviour (for example, angle-dependent fracture and elasticity), highlight the potential of low-molecular-weight compounds to emulate conventional macromolecular systems in terms of their structural sophistication realized by processing. It should be noted that macromolecular systems exhibit superior mechanical properties due to polymer-chain entanglement; therefore, enhancing the mechanical robustness of supramolecular bulk materials will require strategies fundamentally different from those used in commodity plastics. Nevertheless, the recyclability and thermal reshaping capabilities of the material underscore its promise as a sustainable alternative to macromolecule-based plastics. The successful extrusion of metastable Chol-C₁₂ into filaments that display bamboo-like fracture behaviour and enhanced stiffness further illustrates the versatility of this supramolecular platform. Collectively, our findings establish a new approach for designing processable, recyclable, and structurally tuneable bulk materials from small molecules, opening avenues for the next generation of supramolecular bulk materials.

Methods

Syntheses of Chol-C₆, Chol-C₁₂, and Chol-C₁₈, and melt-moulding and extrusion of supramolecular materials are described in Supplementary Information.

Author contributions

K.S. designed the research. C.-H.C., Y.W., and K.S. wrote the manuscript. C.-H.C. synthesized molecules and investigated their thermal and mechanical properties. T.K. conducted XRD, FT-IR, CD measurements. S.S. helped with processing the materials. All the authors discussed the results and have approved the final version of the manuscript.

Peer review

Peer review information

Nature Communications thanks the anonymous reviewers for their contribution to the peer review of this work. A peer review file is available.

Funding

K.S. discloses support for the research of this work from the Japan Society for the Promotion of Science (JSPS) KAKENHI [grant number JP22H02134; JP23K17941; and JP24H01712 in a Grant-in-Aid Scientific Research for Transformative Research Areas (A) “Materials Science of Meso-Hierarchy”]. T.K., S.S., and K.S. disclose support for the research of this work from the Japan Science and Technology Agency (JST) [grant number JPMJCR23L2 in “Precise Material Science for Degradation and Stability”, CREST]. Y.W. discloses support for the research of this work from JST [grant number JPMJAX23DM in “Trans-Scale Approach Toward Materials Innovation, ACT-X”]. K.S. acknowledges financial support from The Murata Science Foundation, Sekisui Chemical Grant Program, The Mitsubishi Foundation, Masuyakinen Basic Research Foundation, Fujimori Science and Technology Foundation, The Samco Foundation, and Toshiaki Ogasawara Memorial Foundation. C.-H.C. was supported by the Kyoto University SPRING program for Young Researchers.

Data availability

The authors declare that the data supporting the findings of this study are available within the paper and its supplementary information file. Should any raw data files be needed in another format, they are available from the corresponding author upon request. Source data are provided with this paper.

Competing interests

The authors declare no competing interests.

Supplementary information

The online version contains supplementary material available at https://doi.org/10.1038/s41467-026-77392-5.