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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]

Giant tetrahedral molecules have sparked significant interest in the past decade due to their unique and diverse supramolecular nanostructures. The longer and bulkier peripheral substituents create deep molecular concavities and thus contribute to the different self‐assembly behaviors compared to the conventional small tetrahedral molecules. In this study, a molecular giant tetrahedra, TetraNDI, was synthesized to investigate the important roles of the molecular concavities in the self‐assembly mechanism. Single‐crystal structural characterizations indicate that the TetraNDI takes its trigonal concavities to form 1D supramolecular columns, and its tetragonal concavities to reach close inter‐columnar packing. The difficulty in occupying the concavities leads to the path‐dependent phase behaviors of the giant tetrahedra. It is also found that the remaining molecular concavities in the supramolecular scaffolds affect the CO2 affinity of TetraNDI. With an understanding of the packing principles of molecular giant tetrahedra, the structure‐property relationships could be better evaluated in the future and might broaden the horizon of porous materials. [ABSTRACT FROM AUTHOR]