Semi‐Crystalline, Three‐Segmented Hybrid Gels with Multiple Shape‐Memory Effect

Abstract

Natural biological systems such as intervertebral disk, tendon, and ligament consist of regions with distinctly different mechanical properties, yet these regions intermesh with each other through an extremely tough interface. Here the authors present mechanically strong, three‐segmented hybrid hydrogels comprising of soft and hard components in a fused body resembling the mechanical heterogeneity of biological materials. An easy UV‐initiated bulk copolymerization method of stratified monomer solutions is used to synthesize three‐segmented hybrid hydrogels. In this method, stratification of the monomer solutions is created by means of the differences in their densities. Thus, the polymerization reactions in the monomer mixtures as well as in the interface regions occur simultaneously resulting in the formation of multi‐segmented hybrid hydrogels consisting of segments with different chemical and physical properties. Hydrophilic and hydrophobic monomer mixtures compositions of stratified solutions selected in this study lead to the formation of supramolecular, semi‐crystalline three‐segmented hybrid hydrogels with adjustable thermal and mechanical properties. They also exhibit thermally induced pseudo multiple shape‐memory function originating from distinctly different melting temperatures of crystalline domains belonging to the gel components of hybrids.

Dispersed Association of Single-Component Short-Alkyl Chains toward Thermally Programmable and Malleable Multiple-Shape Hydrogel

“…Only a few TSMHs exhibit multiple-shape-memory behaviors through thermal transitions of multiple phase domains. , For example, Argun et al have synthesized a class of multisegmented hybrid hydrogels by using copolymerization of stratified monomer solutions. , Their system convincingly demonstrates thermally induced multiple shape-memory functions originating from different melting temperatures of crystalline domains. Despite effectiveness, these multiple phase domains must be constructed by using multicomponent switching segments, making the synthesis challenging due to incompatibility and reaction ratio of the involved monomers.…”

A novel multi‐functional model thermoset and PDA‐coated PU nanocomposite based on graphene and an amphiphilic block copolymer

“…Hence, the low‐SF value for this specimen can be related to its low‐crystallization ability and its low‐elastic modulus in this region. The crystallization of soft segments during the cooling step reduces the possibility of conformational transformations after T g and hence, reducing the spontaneous partial shape recovery 23,47 . The bottom images of Figure 6 show the digital images of the B2 and B5 specimens at different time intervals.…”

“…The crystallization of soft segments during the cooling step reduces the possibility of conformational transformations after T g and hence, reducing the spontaneous partial shape recovery. 23,47 The bottom images of Figure 6 show the digital images of the B2 and B5 specimens at different time intervals. As it can be seen, the two specimens were able to recover the original shape.…”

“…19,21,22 PUs are wellestablished as materials with inherent thermal shape memory behavior. 23,24 Another way to increase functionality of PUs is to modify its surface. A simple and efficient way to achieve this goal is to use Polydopamine (PDA).…”

“…Besides the structural versatility, the PUs also possess an inherent shape memory behavior which makes them a great candidate to build bulk and surface stimuli‐responsive substrates for cell culture in the tissues' dynamic environment 19,21,22 . PUs are well‐established as materials with inherent thermal shape memory behavior 23,24 . Another way to increase functionality of PUs is to modify its surface.…”