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

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

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

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

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

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