An elastomeric, healable, supramolecular polymer blend comprising a chain-folding polyimide and a telechelic polyurethane with pyrenyl end groups is compatibilized by aromatic pi-pi stacking between the pi-electron-deficient diimide groups and the pi-electron-rich pyrenyl units. This interpolymer interaction is the key to forming a tough, healable, elastomeric material. Variable-temperature FTIR analysis of the bulk material also conclusively demonstrates the presence of hydrogen bonding, which complements the pi-pi stacking interactions. Variable-temperature SAXS analysis shows that the healable polymeric blend has a nanophase-separated morphology and that the X-ray contrast between the two types of domain increases with increasing temperature, a feature that is repeatable over several heating and cooling cycles. A fractured sample of this material reproducibly regains more than 95% of the tensile modulus, 91% of the elongation to break, and 77% of the modulus of toughness of the pristine material.

A series of six low molecular weight elastomers with hydrogen bonding end-groups have been designed, synthesised and studied. The poly(urethane) based elastomers all contained essentially the same hard block content (ca. 11%) and differ only in the nature of their end-groups. Solution state 1 H NMR spectroscopic analysis of model compounds featuring the end-groups demonstrate that they all exhibit very low binding constants, in the range 1.4 to 45.0 M-1 in CDCl 3 , yet the corresponding elastomers each possess a markedly different nanoscale morphology and rheology in the bulk. We are able to correlate small variations of the binding constant of the end-groups with dramatic changes in the bulk properties of the elastomers. These results provide an important insight into the way in which weak non-covalent interactions can be utilized to afford a range of self-assembled polyurethane based materials that feature different morphologies.

Control of the nucleation and growth process in self-assembled fibrillary networks (SAFiN) with the goal of preparing physical hydrogels from low molecular weight gelators (LMWG) is well-established but mainly for temperature-driven hydrogelators. In the presence of other stimuli, like pH, the fundamental knowledge behind gel formation still lacks. In particular, whether pH affects nucleation and growth of the fibers and how this aspect could be related to the stability of the hydrogel is still matter of debate. In this work, we establish a precise relationship between the pH change rate during the micelle-to-fiber transition, observed for stearic acid sophorolipids-a bolaform microbial glycolipidand supersaturation. We show that tough SAFiN hydrogels are obtained for slow pH change rates, when supersaturation is low, while weak gels, or even phase separation through powder precipitation, are obtained upon fast pH change. Interestingly, these results are independent of the pH change method, may it be through manual variation using HCl, or by using the internal hydrolysis of glucono-δ-lactone (GDL), the latter being currently acknowledged as a unique way to systematically obtain tough gel through internal pH change.

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Dispersing micronized fat crystals (MFCs) in oil is a novel route to largely decouple fat crystallisation and network formation and thus to simplify the manufacture of fat-continuous food products. MFCs dispersed in oil form a weak-interaction network organized by crystal aggregates in a continuous net of crystalline nanoplatelets. The rough surface of MFC nanoplatelets hampers stacking into one-dimensional aggregates, which explains the high mass fractal dimensions of the networks formed in MFC dispersions. Applying shear does not have a significant effect on the fractal dimensions of MFC networks, and MFC aggregates in the range of 5-10 μm remain intact. However, shear leads to a significant loss of storage modulus and yield stress over a time frame of an hour. This can be attributed to irreversible disruption of the continuous net of nanoplatelets. Rheo-SAXS revealed that shear releases nanoplatelets from the continuous net, which subsequently align in the shear field and undergo rapid recrystallisation. The release of thin and metastable nanoplatelets from the weak-link network bears relevance for simplified and more effective manufacturing of emulsified food products by effectively decoupling crystallisation, network formation and emulsification.

In this work we present a study on the effect of the aggregation on the optical properties of star-shaped molecules. We analyzed the modification of the absorption and fluorescent properties of a 1,3,5-tristyrylbenzene core due to the formation of diverse aggregates. The nature of the aggregates in solution was investigated by different spectroscopic techniques such as electronic absorption, steady-state fluorescence, fluorescence anisotropy, time-resolved fluorescence, small-angle X-ray scattering, and dynamic lightscattering spectroscopy. In order to simulate the molecular arrangement of the aggregates, the structure and electronic properties of different clusters formed by stacking of starshaped molecules were studied by means of density functional theory calculations. The theoretical insight was performed in the gas phase as well as in solution through the polarizable continuum model, and both linear response and state-specific polarization schemes were applied. In the solid state, high quantum yields of up to 0.51 were measured for a 1,3,5-tristyrylbenzene derivative. Finally, the morphological properties of different solid samples were analyzed by differential scanning calorimetry, as well as scanning and transmission electron microscopies.

The double gyroid network morphology has been the focus of extensive research efforts as one of the most appealing block copolymer structures for practical applications. We performed an extensive study of the phase behavior of the supramolecular complex PS-b-P4VP(PDP) x to develop a systematic route to its double gyroid morphology. The morphological characterization of complexes was accomplished by transmission electron microscopy (TEM) and smallangle X-ray scattering (SAXS). Several compositions with the cubic Ia3̅ d symmetry were found in a narrow region between the lamellar and the cylindrical phase. Experimental TEM images were compared to computer simulations of projections through multiple gyroid planes. Typical gyroid patterns"double wave" and "wagon wheel"were regularly found. The size of the gyroid unit cell was calculated from the SAXS data. The lattice parameter could be varied (from ca. 70 to 125 nm) by altering the molar mass of the block copolymer precursors. A number of complexes were found to exhibit characteristic biphasic morphologiescoexisting lamellar and gyroid phase or gyroid and cylindrical phase. Finally, gyroid complexes with different relative PDP ratios were obtained which provides the opportunity to generate nanoporous structures with tunable porosities by dissolving the amphiphiles.

A. (2019) Selfassembling peptide-based hydrogel: regulation of mechanical stiffness and thermal stability and 3D cell culture of fibroblasts. ACS Applied Bio Materials, 2 (12). pp. 5235-5244.