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The impact of additives on the nanoscale structures of spin‐cast polymer composite films, particularly in polymer solar cells, is a topic of significant interest. This study focuses on the blend film comprising poly(thieno[3,4‐b]thiophene‐alt‐benzodithiophene) (PTB7) and [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM), exploring how additives like 1,8‐diiodooctane (DIO) influence the film structures spin‐cast from chlorobenzene solution. Combined results of specular X‐ray and neutron reflectivity, grazing‐incidence small‐ and wide‐angle X‐ray scattering (GISAXS and GIWAXS), and X‐ray photoelectron spectroscopy indicate that DIO could significantly enhance the dispersion of PC71BM and reduce composition inhomogeneity in the film. Time‐resolved GISAXS–GIWAXS with 100 ms resolution further captures a rapid spinodal decomposition of the mixture within 1 s in the constant‐evaporation stage of spin‐casting. Further combined with parallel analysis of time‐resolved UV–Vis reflectance, these findings reveal that DIO mitigates the spinodal decomposition process by accelerating solvent evaporation, which, in turn, decelerates phase segregation, leading to a nucleation‐driven process. These observations provide mechanistic insights into the role of additives in controlling the nanostructural evolution of spin‐cast films by altering the kinetics of solvent evaporation and phase separation during the spin‐coating process. [ABSTRACT FROM AUTHOR]

The first integration of dual slide-ring motion of [c2] daisy chain molecules (as backbones) and α-cyclodextrin (α-CD)-based polyrotaxanes (as cross-linkers) into mechanofluorophoric polyurethane (PU) frameworks was successfully proceeded through step-growth polymerization to yield PU films with distinctive mechanical and optical properties under stress. The intrinsic elastic and stretchable capabilities of the PU films consisting of both mechanically interlocked molecules (MIMs) via the molecular design of daisy chain backbones and polyrotaxane cross-linkers with long gliding movements were evidently enhanced, where the contributions of both extended/contracted forms in daisy chains and different α-CD numbers in polyrotaxane cross-linkers were also investigated. Moreover, reversible ratiometric fluorescence and energy transfer features between green-emitting naphthalimide donors and yellow-orange-emitting mechanofluorophoric rhodamine acceptors could be attained during stretching and relaxation processes. In addition, the stretching deformation of PU films was studied using X-ray diffraction (XRD) techniques for confirming the correlated morphological properties of stretching states in the oriented PU films. Appealingly, notable shape recovery and reversible ratiometric mechanofluorescence behavior of PU films could be achieved upon heating, signifying the potential of PU films with artificial molecular muscle functions of daisy chains accompanied by pulley effects of polyrotaxane cross-linkers, offering excellent mechanical and optical characteristics for various applications in advanced functional materials. [ABSTRACT FROM AUTHOR]

Self-healing properties, originating from the natural healing process, are highly desirable for the fitness-enhancing functionality of biomimetic materials. Herein, we fabricated the biomimetic recombinant spider silk by genetic engineering, in which Escherichia coli (E. coli) was employed as a heterologous expression host. The self-assembled recombinant spider silk hydrogel was obtained through the dialysis process (purity > 85%). The recombinant spider silk hydrogel with a storage modulus of ~250 Pa demonstrated autonomous self-healing and high strain-sensitive properties (critical strain ~50%) at 25 °C. The in situ small-angle X-ray scattering (in situ SAXS) analyses revealed that the self-healing mechanism was associated with the stick-slip behavior of the β-sheet nanocrystals (each of ~2–4 nm) based on the slope variation (i.e., ~−0.4 at 100%/200% strains, and ~−0.9 at 1% strain) of SAXS curves in the high q-range. The self-healing phenomenon may occur through the rupture and reformation of the reversible hydrogen bonding within the β-sheet nanocrystals. Furthermore, the recombinant spider silk as a dry coating material demonstrated self-healing under humidity as well as cell affinity. The electrical conductivity of the dry silk coating was ~0.4 mS/m. Neural stem cells (NSCs) proliferated on the coated surface and showed a 2.3-fold number expansion after 3 days of culture. The biomimetic self-healing recombinant spider silk gel and thinly coated surface may have good potential in biomedical applications. [ABSTRACT FROM AUTHOR]

We present a breakthrough in the synthesis and development of functional gas-responsive materials as highly potent anticancer agents suitable for applications in cancer treatment. Herein, we successfully synthesised a stimuli-responsive multifunctional material (I-R6G) consisting of a carbon dioxide (CO2)-sensitive imidazole moiety and spirolactam-containing conjugated rhodamine 6G (R6G) molecule. The resulting I-R6G is highly hydrophobic and non- or weakly fluorescent. Simple CO2 bubbling treatment induces hydrophobic I-R6G to completely dissolve in water and subsequently form self-assembled nanoparticles, which exhibit unique optical absorption and fluorescence behaviours in water and extremely low haemolytic ability against sheep red blood cells. Reversibility testing indicated that I-R6G undergoes reversible CO2/nitrogen (N2)-dependent stimulation in water, as its structural and physical properties can be reversibly and stably switched by alternating cycles of CO2 and N2 bubbling. Importantly, in vitro cellular assays clearly demonstrated that the CO2-protonated imidazole moiety promotes rapid internalisation of CO2-treated I-R6G into cancer cells, which subsequently induces massive levels of necrotic cell death. In contrast, CO2-treated I-R6G was not internalised and did not affect the viability of normal cells. Therefore, this newly created system may provide an innovative and efficient route to remarkably improve the selectivity, safety and efficacy of cancer treatment. [ABSTRACT FROM AUTHOR]

Visualizing color changes upon mechanical force in elastomers is attractive to understand stress transfer and failure mechanisms, which is valuable for applications ranging from tamper-proof packaging to structural integrity monitoring. Herein, we synthesize mechanochromic polyurethane films with an optimum stretchability (5500% strain) and a strongest toughness (324 MJ m−3) by using the components of bis-functionalized rhodamine, Diels–Alder (DA) adduct, 2-hydroxyethyl disulfide (HEDS), polyethylene glycol, triethanolamine and hexamethylene diisocyanate via condensation polymerization. The additions of HEDS and DA moieties enhance the healing efficiency up to 87% after 24 h of curing induced by disulfide bond exchange and Diels–Alder and retro-Diels–Alder reactions. The polyurethane film exhibits a green emission (450–500 nm) before stretching, but it shows an orange-red emission (588 nm) by force stretching because of the open form of the rhodamine moieties. A high shape recovery of 90.9% and reversible mechano-fluorescence switching by heating (immersed in 60 °C hot water) after structural deformations make it useful for shape memory and soft robotic applications. Finally, a high dielectric permittivity (160 at 1 Hz) and a good capacitance value (0.28 nF cm−2 at 1 Hz) of the film exhibit its potential applications as a flexible capacitor for energy storage in modern flexible devices. [ABSTRACT FROM AUTHOR]

Poly(ethylene succinate) (PESu), upon crystallization with a morphology‐modulating diluent and at low degree of supercooling, forms peculiarly novel sector‐face dendritic aggregates. Delicate dissection by various microscopic techniques is used to confirm the unique differences of these two faces in the PESu dendrites. Powerful synchrotron‐source generated X‐ray microbeam analysis is performed to prove without doubt the nature of the single crystals that self‐assemble into these two sectors, respectively. Both microscopy results and 1D/2D wide‐angle X‐ray patterns collectively confirm that one sector‐face of the PESu dendrites is composed all fully flat‐on with the single‐crystal's basal face contacting the substrate and branching growth with mutual perpendicular ≈90° angle intersections; the second face is composed fully edge‐on with the prism face contacting the substrate and growth with mutual oblique 5–30° angle intersections. The growth intersection angles are also proved by the azimuthal angles in 1D and 2D X‐ray patterns. [ABSTRACT FROM AUTHOR]

Transition metal high‐entropy oxides (HEOs) are an attractive class of anode materials for high‐performance lithium‐ion batteries (LIBs). However, owing to the multiple electroactive centers of HEOs, the Li+ storage mechanism is complex and debated in the literature. In this work, operando quick‐scanning X‐ray absorption spectroscopy (XAS) is used to study the lithiation/delithiation mechanism of the Cobalt‐free spinel (CrMnFeNiCu)3O4 HEO. A monochromator oscillation frequency of 2 Hz is used and 240 spectra are integrated to achieve a 2 min time resolution. High‐photon‐flux synchrotron radiation is employed to increase the XAS sensitivity. The results indicate that the Cu2+ and Ni2+ cations are reduced to their metallic states during lithiation but their oxidation reactions are less favorable compared to the other elements upon delithiation. The Mn2+/3+ and Fe2+/3+ cations undergo two‐step conversion reactions to form metallic phases, with MnO and FeO as the intermediate species, respectively. During delithiation, the oxidation of Mn occurs prior to that of Fe. The Cr3+ cations are reduced to CrO and then Cr0 during lithiation. A relatively large overpotential is required to activate the Cr reoxidation reaction. The Cr3+ cations are found after delithiation. These results can guide the material design of HEOs for improving LIB performance. [ABSTRACT FROM AUTHOR]