We report the fabrication of scroll-like scaffolds with anisotropic topography using 4D printing based on a combination of 3D extrusion printing of methacrylated alginate, melt-electrowriting of polycaprolactone fibers, and shape-morphing of the fabricated object. A combination of 3D extrusion printing and melt-electrowriting allows programmed deposition of different materials and fabrication of structures with high resolution. Shape-morphing allows the transformation of a patterned surface of a printed structure in a pattern on inner surface of a folded object that is used to align cells. We demonstrate that the concentration of calcium ions, the environment media, and the geometrical shape of the scaffold influences shape-morphing that allows it to be efficiently programmed. Myoblasts cultured inside a scrolled bilayer scaffold demonstrate excellent viability and proliferation. Moreover, the patterned surface generated by PCL fibers allow a very high degree of orientation of cells, which cannot be achieved on the alginate layer without fibers.

This paper reports an approach for the fabrication of shape-changing bilayered scaffolds, which allow the growth of aligned skeletal muscle cells, using a combination of 3D printing of hyaluronic acid hydrogel, melt electrowriting of thermoplastic polycaprolactone-polyurethane elastomer, and shape transformation. The combination of the selected materials and fabrication methods allows a number of important advantages such as biocompatibility, biodegradability, and suitable mechanical properties (elasticity and softness of the fibers) similar to those of important components of extracellular matrix (ECM), which allow proper cell alignment and shape transformation. Myoblasts demonstrate excellent viability on the surface of the shapechanging bilayer, where they occupy space between fibers and align along them, allowing efficient cell patterning inside folded structures. The bilayer scaffold is able to undergo a controlled shape transformation and form multilayer scroll-like structures with cells encapsulated inside. Overall, the importance of this approach is the fabrication of tubular constructs with a patterned interior that can support the proliferation and alignment of muscle cells for muscle tissue regeneration.

Polyesters with 9,10‐dihydro‐9‐oxy‐10‐phosphaphenanthrene‐10‐oxide‐containing comonomers are synthesized aiming to improve the flame retardancy of aliphatic polyesters such as poly(butylene succinate) and poly(butylene sebacate). The influence of the chemical structure on the thermal decomposition and pyrolysis is examined using a combination of thermogravimetric analysis (TGA), TGA‐Fourier transform infrared (FTIR) spectroscopy, pyrolysis‐gas chromatography/mass spectrometry, and microscale combustion flow calorimetry. Thermal decomposition pathways are derived and used to select suitable candidates as flame retardants for PBS. The fire behavior of the selected polymers is evaluated by forced‐flaming combustion in a cone calorimeter. The materials show two modes of action for flame retardancy: strong flame inhibition due to the release of a variety of molecules combined with charring in the solid state.

Icing of various surfaces is often a result of the collision of supercooled water drops with substrates. Ice formation from supercooled water drops is initiated by nucleation when the size of an ice embryo reaches a critical value. The lack of controlling the inception of heterogeneous nucleation and the rate of solidification, which depend on the properties of the substrate, temperature, and impact parameters of the liquid drop, poses a very serious challenge to the design of effective ice-preventing materials. In this exploratory experimental study, we show how a significant nucleation delay during impact of supercooled water drops can be achieved by tuning the properties of the substrate and, specifically, by introducing chemical and topographical heterogeneities on the surfaces formed by a mixture of either polymer-coated hydrophilic and hydrophobic particles or Janus particles. We have discovered that the nucleation rate during drop impact is significantly reduced on heterogeneous surfaces formed by a mixture of hydrophilic and hydrophobic particles. Exceptionally, freezing is completely prevented on surfaces made of amphiphilic Janus particles. Even after a repetition of 100 drop impact experiments, no single drop froze at all. After impact of the supercooled water drops, a rebound occurs, and afterwards smaller secondary drops are formed, which can be easily removed. Moreover, the designed surfaces demonstrate good scratch resistance and robustness. The presented findings open a promising pathway for the rational design of effective passive ice-preventing coatings using Janus particles as building blocks.