Showing papers by "Yoshinori Takashima published in 2017"

Multifunctional Stimuli-Responsive Supramolecular Materials with Stretching, Coloring, and Self-Healing Properties Functionalized via Host–Guest Interactions

Abstract: The visualization of changes in the stress and bonding state inside polymeric materials is an attractive function in materials science In this study, phenolphthalein (PP) was selected to prepare stimuli-responsive coloring materials PP becomes purple under basic conditions in aqueous solutions; however, PP becomes colorless under basic conditions when it forms a complex with β-cyclodextrin (βCD) To exploit this property of PP, we prepared a color-changing hydrogel (βCD-PP AAm hydrogel) based on acrylamide (AAm) as the main chain and βCD and PP moieties as the side chains The βCD-PP AAm hydrogel exhibits a color change when heat or a competing molecule is applied at a pH less than 8 This color change was confirmed by ultraviolet–visible (UV–vis) spectroscopy, and the mechanical properties were determined via compression and tensile measurements The βCD-PP AAm hydrogel also exhibits a rapid, reversible color change upon Joule heating produced by an electric current passing through the gel

Supramolecular Materials Cross-Linked by Host–Guest Inclusion Complexes: The Effect of Side Chain Molecules on Mechanical Properties

Abstract: Functional polymeric materials constructed by noncovalent bonds have attracted considerable attention due to their beneficial stretching and self-healing properties. We chose host–guest interactions using cyclodextrins (CDs) as host molecules to realize supramolecular materials with stretching and self-healing properties. Notably, an inclusion complex of a CD and a guest molecule functions as a reversible bond in a material. Herein, we studied the relationship between the mechanical properties of the materials and host–guest interactions based on the association constants of CDs with guest molecules and molecular structures of the guest molecules. A chemically cross-linked poly(acrylamide) gel showed high rupture stress, although the rupture strain was noticeably low. However, the host–guest hydrogels (CDAAmMe-R hydrogels) exhibited a higher rupture stress and strain of approximately 1000%. These rupture stress and strain values were related to the association constants of the CDs with guest units on the ...

Dynamic Mechano-Regulation of Myoblast Cells on Supramolecular Hydrogels Cross-Linked by Reversible Host-Guest Interactions.

Abstract: A new class of supramolecular hydrogels, cross-linked by host-guest interactions between β-cyclodextrin (βCD) and adamantane, were designed for the dynamic regulation of cell-substrate interactions. The initial substrate elasticity can be optimized by selecting the molar fraction of host- and guest monomers for the target cells. Moreover, owing to the reversible nature of host-guest interactions, the magnitude of softening and stiffening of the substrate can be modulated by varying the concentrations of free, competing host molecules (βCD) in solutions. By changing the substrate elasticity at a desired time point, it is possible to switch the micromechanical environments of cells. We demonstrated that the Young’s modulus of our “host-guest gels”, 4–11 kPa, lies in an optimal range not only for static (ex situ) but also for dynamic (in situ) regulation of cell morphology and cytoskeletal ordering of myoblasts. Compared to other stimulus-responsive materials that can either change the elasticity only in one direction or rely on less biocompatible stimuli such as UV light and temperature change, our supramolecular hydrogel enables to reversibly apply mechanical cues to various cell types in vitro without interfering cell viability.

Movable Cross-Linked Polymeric Materials from Bulk Polymerization of Reactive Polyrotaxane Cross-Linker with Acrylate Monomers

Abstract: Topological cross-linked polymers attract much attention from their unique mechanical properties derived from their cross-linking structure. Here, we have fabricated a polymeric material (Acryl-AcO-PRx) incorporating topological cross-links into various universal acrylate polymers by using a modified polyrotaxane as a polymerizable cross-linking agent. Acryl-AcO-PRx obtained by a simple photocuring technique under bulk conditions showed a distinctly higher extensibility compared with the chemical cross-linked polymers. In addition, Acryl-AcO-PRx materials showed high stress relaxation and deformation hysteresis. These results indicate that the topologically cross-linked structure composed of polyrotaxane plays an important role in mechanical properties even in bulk state.

Supramolecular Polymeric Materials Containing Cyclodextrins.

Abstract: Smart design of polymeric materials may lead to intelligent materials exhibiting unique functional properties. Looking at nature, living systems use specific and reversible intermolecular interactions in realizing complex functions. Hence reversible bonds based on selective molecular recognition can impart artificial materials with unique functional properties. This review mainly focuses on supramolecular polymeric materials based on cyclodextrin-based host-guest interactions. Polymeric materials using molecular recognition at polymer main chain, side chain, and termini are described. Polymers carrying host and guest residues exhibit unique properties such as: 1) formation of macroscopic self-assembly of polymer gels carrying host and guest residues; 2) stimuli-responsive self-healing properties due to the reversible nature of host-guest interactions; and 3) macroscopic motion of artificial muscle cross-linked by host-guest interaction controlled by external stimuli. An overview of recent developments in this new frontier between materials science and life science is given.

Stimuli-responsive polymeric materials functioning via host–guest interactions

Abstract: Molecular recognition is essential for realizing functional supramolecular materials. Non-covalent host–guest interactions are an effective tool to introduce switching and functional properties into materials. This review focuses on the achievement of selective molecular adhesion, self-healing, toughness, and actuation properties. These functions have been achieved by reversible bond formation with cyclodextrins (CDs). Self-healing materials with host–guest interactions involving CDs have been used to achieve redox-responsive healing properties and healing efficiency. Furthermore, the materials, which undergo self-healing by chemical and physical mechanisms, exhibit rapid and efficient self-healing properties under semi-dry conditions. To prepare a supramolecular actuator using host–guest complexes, two approaches have been introduced. The first is the functionalization of a supramolecular gel actuator by changing the cross-linking density, and the second is the functionalization of a topological gel actuator by changing distances between the cross-linking points. Both actuators exhibit contractive bending behavior. This review summarizes advancements within the past 10 years in supramolecular materials that function via the chemical mechanism of host–guest interactions and the physical mechanism of the sliding motion of ring molecules.

Functioning via host–guest interactions

Abstract: Molecular recognition is essential for realizing functional supramolecular materials. Non-covalent host–guest interactions are an effective tool to introduce switching and functional properties into materials. This review focuses on the achievement of selective molecular adhesion, self-healing, toughness, and actuation properties. These functions have been achieved by reversible bond formation with cyclodextrins (CDs). Self-healing materials with host–guest interactions involving CDs have been used to achieve redox-responsive healing properties and healing efficiency. Furthermore, the materials, which undergo self-healing by chemical and physical mechanisms, exhibit rapid and efficient self-healing properties under semi-dry conditions. To prepare a supramolecular actuator using host–guest complexes, two approaches have been introduced. The first is the functionalization of a supramolecular gel actuator by changing the cross-linking density, and the second is the functionalization of a topological gel actuator by changing distances between the cross-linking points. Both actuators exhibit contractive bending behavior. This review summarizes advancements within the past ten years in supramolecular materials that function via the chemical mechanism of host–guest interactions and the physical mechanism of the sliding motion of ring molecules.

Method for producing polyrotaxane

Abstract: This invention provides a method for producing a polyrotaxane, the method being capable of producing a polyrotaxane in a high yield within a short period of time, using a small number of steps. The method for producing the polyrotaxane of the present invention is a method for producing a polyrotaxane having a structure in which a linear molecule passes through openings of cyclic molecules, the method comprising the step of heating a starting material containing the linear molecule and the cyclic molecule to the melting temperature of the linear molecule or higher, to obtain a clathrate compound of the linear molecule and the cyclic molecule.