These typically resemble the extracellular matrix in mechanical behavior as well as allow diffusion of nutrients so that SMH are of especial interest for biomedicine. Shape-memory hydrogels (SMH) are SMPs formed from hydrophilic polymers that are swollen in water. In addition, such biopolymer-based switching segments might impart degradability into the SMP, resulting in multifunctional materials. This has inspired utilizing biopolymers as switching segments in shape-memory polymers (SMP). As the conformations are based on non-covalent interactions, they can be altered, and, potentially, switched “on” or “off”, by changing the environment, such as pH, presence and concentration of ions or individual molecules, or temperature. The conformation is associated with the biological function of the protein, such as specificity in biological interactions or its mechanical performance. The adoption of preferred conformations is sequence (primary structure)-dependent, and is therefore inherently included information. Protein conformations are generally much more studied and better understood than, e.g., polysaccharide conformations. These conformations, typically referred to as secondary structures (short-range interactions), tertiary structures (overall conformation of a single chain), and quarternary structures (overall structure involving several polymer chains) are related to the non-covalent interactions between the functional groups and with water as well as the stereoelectronic effects of substituents along the chain. The large variety of functional groups present in biopolymers such as nucleic acids and proteins gives rise to thermodynamically preferred conformations of such biomacromolecules in an aqueous environment. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R r close to 100% were observed.
RECOVERY MAP QUANTUM ERROR CORRECTION FULL
The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 ☌ and pH = 7.4. Hydrogels had storage moduli of 0.27–23 kPa and Young’s moduli of 215–360 kPa at 4 ☌. The ability to form triple helices increased with the molar mass of the crosslinker. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) α,ω-dithiols of varying crosslinker length and amount. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine.
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