A.A.Broekhuis@rug.nl with the processability and recyclability of thermoplastic ones. [ 6 ] The concept behind re-workable thermosets is that part of the polymer network can be de-crosslinked by applying an external stimulus, the latter being for example light [ 7 ] or heat. These networks can either consist of covalent or non-covalent crosslinks. Examples of non-covalent reversible crosslinks are hydrogen bonds, [ 8 , 9 ] and ionic [ 10 ] or Van der Waals interactions (e.g., SBS rubber). [ 11 , 12 ] All these physical bonds have been demonstrated to selectively break at a given de-crosslinking temperature. On the other hand, covalently reversible chemical crosslinks are based on chemical bonds that can be broken upon an external stimulus, mainly heat or radiation energy. The most studied thermoreversible chemical systems are based on the Diels-Alder (DA) reaction [ 13 ] probably because it ensures fast kinetics and a high number of recycles with little, if any, degradation [ 14 ] between 50 ° C and 200 ° C. In order to create a 3D crosslinked network, several systems have been employed based on the [4 + 2] DA reaction and its reverse. These systems consist of multiple dienophile and diene moieties of low molecular weight, [ 15 ] of dienes or dienophiles attached to polymer backbones crosslinked with bi-functional low molecular weight crosslinker, or of polymeric chains containing both diene and dienophile. [ 16 ]

A profound understanding of how to tailor surface topographies of electrospun fibers is of great importance for surface sensitive applications including optical sensing, catalysis, drug delivery and tissue engineering. Hereby, a novel approach to comprehend the driving forces for fiber surface topography formation is introduced through inclusion of the dynamic solvent-polymer interaction during fiber formation. Thus, the interplay between polymer solubility as well as computed fiber jet surface temperature changes in function of time during solvent evaporation and the resultant phase separation behavior are studied. The correlation of experimental and theoretical results shows that the temperature difference between the polymer solution jet surface temperature and the dew point of the controlled electrospinning environment are the main influencing factors with respect to water condensation and thus phase separation leading to the final fiber surface topography. As polymer matrices with enhanced surface area are particularly appealing for sensing applications, we further functionalized our nanoporous fibrous membranes with a phosphorescent oxygen-sensitive dye. The hybrid membranes possess high brightness, stability in aqueous medium, linear response to oxygen and hence represent a promising scaffold for cell growth, contactless monitoring of oxygen and live fluorescence imaging in 3-D cell models.

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Toncelli, C. (2019). Mussel-inspired injectable hydrogel adhesive formed under mild conditions features near-native tissue properties. ACS Applied Materials and Interfaces.