Soluble-insoluble Changes Research Articles

Design of a Tunable Self‐Oscillating Polymer with Ureido and Ru(bpy)3 Moieties

AbstractAn upper critical solution temperature (UCST)‐type self‐oscillating polymer was designed that exhibited rhythmic soluble–insoluble changes induced by the Belousov–Zhabotinsky (BZ) reaction. The target polymers were prepared by conjugating Ru(bpy)3, a catalyst for the BZ reaction, to ureido‐containing poly(allylamine‐co‐allylurea) (PAU) copolymers. The Ru(bpy)3‐conjugated PAUs exhibited a UCST‐type phase‐transition behavior, and the solubility of the polymer changed in response to the alternation in the valency of Ru(bpy)3. The ureido content influences the temperature range of self‐oscillation, and the oscillation occurred at higher temperatures than conventional LCST‐type self‐oscillating polymers. Furthermore, the self‐oscillating behavior of the Ru‐PAU could be regulated by addition of urea, which is a unique tuning strategy. We envision that novel self‐oscillating polymers with widely tunable soluble‐insoluble behaviors can be rationally designed based these UCST‐type polymers.

Design of a Tunable Self-Oscillating Polymer with Ureido and Ru(bpy)3 Moieties.

An upper critical solution temperature (UCST)-type self-oscillating polymer was designed that exhibited rhythmic soluble-insoluble changes induced by the Belousov-Zhabotinsky (BZ) reaction. The target polymers were prepared by conjugating Ru(bpy)3 , a catalyst for the BZ reaction, to ureido-containing poly(allylamine-co-allylurea) (PAU) copolymers. The Ru(bpy)3 -conjugated PAUs exhibited a UCST-type phase-transition behavior, and the solubility of the polymer changed in response to the alternation in the valency of Ru(bpy)3 . The ureido content influences the temperature range of self-oscillation, and the oscillation occurred at higher temperatures than conventional LCST-type self-oscillating polymers. Furthermore, the self-oscillating behavior of the Ru-PAU could be regulated by addition of urea, which is a unique tuning strategy. We envision that novel self-oscillating polymers with widely tunable soluble-insoluble behaviors can be rationally designed based these UCST-type polymers.

Self-oscillating soluble-insoluble changes of polymer chain induced by the BZ reaction with Fe(phen)3 catalyst

A novel self-oscillation polymer was successfully synthesized by covalently bonding the Fe(phen)3 catalyst for the BZ reaction onto the poly(N-isopropylacrylamide) polymer chain. The lower critical solution temperatures (LCST) of the polymer chain in the reduced and oxidized states were 37 and 32 °C, respectively. The prepared polymer solution can undergo soluble-insoluble self-oscillation induced by the BZ reaction at constant temperature.

Self-oscillation of polymer and photo-regulation by introducing photochromic site to induce LCST changes

We have developed polymers and gels with autonomous self-oscillating function by utilizing the Belousov–Zhabotinsky (BZ) reaction. The self-oscillating polymer is composed of poly(N-isopropylacrylamide), in which ruthenium tris(2,2′-bipyridine) is copolymerized as a catalyst for the BZ reaction. Under the coexistence of the reactants, the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. In this study, spirobenzopyran was introduced into the self-oscillating polymer as the photochromic site. Under acidic condition necessary for the BZ reaction, photochromism of the spirobenzopyran occurs and the lower critical solution temperature of the polymer solution shifts to lower temperature with isomerization by photo-irradiation. As a result, on–off switching of the soluble–insoluble self-oscillation for the polymer solution is possible by photo-irradiation.

Self-Oscillating Polymer Gels as Novel Smart Materials

ABSTRACTAs a novel biomimetic polymer gel, we have been studying polymer gels with an autonomous self-oscillating function, since firstly reported in 1996. For developing the polymer gels, we utilized oscillating chemical reaction, called the Belousov-Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer gel is composed of a poly(N-isopropylacrylamide) network in which the metal catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous swelling-deswelling changes (in the case of gel) or cyclic soluble-insoluble changes (in the case of an uncrosslinked polymer) without any on-off switching of external stimuli. Several kinds of functional material systems utilizing self-oscillating polymers and gels such as biomimetic actuators, mass transport surface, etc. are expected. Here recent progress on self-oscillating polymers and gels and the design of functional material systems are summarized.

Self-oscillating polymer gel as novel biomimetic materials exhibiting spatiotemporal structure

As a novel biomimetic polymer gel, we have been studying polymer gel with an autonomous self-oscillating function since it was firstly reported in 1996. For developing the polymer gels, we utilized an oscillating chemical reaction, called the Belousov–Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer gel is composed of a poly(N-isopropylacrylamide) network in which the metal catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous swelling–deswelling changes (in the case of gel) or cyclic soluble–insoluble changes (in the case of uncross-linked polymer) without any on–off switching of external stimuli. Several kinds of functional material systems utilizing the self-oscillating polymer and gel such as biomimetic actuators, mass transport surface, etc. are expected. Here, these recent progress on the self-oscillating polymer and gels and the design of functional material systems are summarized.

Development of self-oscillating polymers and gels with autonomous function

In this study, polymers with an autonomous self-oscillating function were examined to obtain a novel biomimetic polymer. The author succeeded in developing a novel self-oscillating polymer and gel by using the oscillating reaction called the Belousov–Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of reactants, the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. Several kinds of functional material systems using self-oscillating polymer and gel, such as biomimetic actuators and mass transport surfaces, are expected. To obtain a novel biomimetic polymer, we have been studying polymers with an autonomous self-oscillating function. We succeeded in developing a novel self-oscillating polymer and gel by using an oscillating reaction, called the Belousov–Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. Under the coexistence of the reactants, the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. Several kinds of functional material systems using the self-oscillating polymer and gel, such as biomimetic actuators, mass transport surface and so on, are expected.

Self‐Oscillating Gels Driven by the Belousov–Zhabotinsky Reaction as Novel Smart Materials

So far stimuli-responsive polymer gels and their application to smart materials have been widely studied; this research has contributed to progress in gel science and engineering. For their development as a novel biomimetic polymer, studies of polymers with an autonomous self-oscillating function have been carried out since the first reports in 1996. The development of novel self-oscillating polymers and gels have been successful utilizing the oscillating reaction, called the Belousov-Zhabotinsky (BZ) reaction, which is recognized as a chemical model for understanding several autonomous phenomena in biological systems. The self-oscillating polymer is composed of a poly(N-isopropylacrylamide) network in which the catalyst for the BZ reaction is covalently immobilized. In the presence of the reactants, the polymer undergoes spontaneous cyclic soluble-insoluble changes or swelling-deswelling changes (in the case of gel) without any on-off switching of external stimuli. Potential applications of the self-socillating polymers and gels include several kinds of functional material systems, such as biomimetic actuators and mass transport surface.

Self-Oscillating Polymer and Gels as Novel Biomimetic Materials

Abstract Stimuli-responsive polymers and their application to biomaterials have been widely studied. On the other hand, as a novel biomimetic polymer, we have been studying a polymer with an autonomous self-oscillating function by utilizing oscillating chemical reactions. So far, we have succeeded in developing a novel self-oscillating polymer and gels by utilizing the Belousov–Zhabotinsky (BZ) reaction. The self-oscillating polymer is composed of poly(N-isopropylacrylamide) (PNIPAAm), in which Ru(bpy)32+ is incorporated as a catalyst for the BZ reaction. Under the coexistence of the reactants (malonic acid, sodium bromate, and nitric acid), the polymer undergoes spontaneous cyclic soluble–insoluble changes or swelling–deswelling changes (in the case of gel) without any on–off switching of external stimuli. In this paper, our recent studies on the self-oscillating polymer and the design of functional material systems using the polymer are summarized.

Characterization of a self-oscillating polymer with periodic soluble-insoluble changes

A copolymer of N-isopropylacrylamide (NIPAAm), ruthenium-complex (Ru(bpy) 3 ), and N-succinimidyl acrylic acid (NAS) was synthesized to investigate its selfoscillating properties in a solution. This polymer exhibits selfoscillation in turbidity and viscosity synchronized via a Belousov-Zhabotinsky (BZ) reaction. The molecular size of the polymer during oscillation was investigated by dynamic light scattering and electrochemical measurements. Both molecular size and viscosity exhibited periodic changes during the BZ reaction. A simple mechanism accounting for such periodic changes was investigated by numerical calculations.

Preparation of Spatio-temporal Functional Surface using Self-oscillating Gel

Stimuli-responsive polymers and their applications to sensors and actuators are widely studied. On the other hand, we have prepared the novel self-oscillating polymer and gels by utilizing the chemical energy of Belousov-Zhabotinsky (BZ) reaction. The polymer is composed of poly (N-isopropylacrylamide) in which Ru (bpy)3, a catalyst for the Belousov-Zhabotinsky (BZ) reaction, is covalently bonded to the polymer chain. Under the coexistence of the reactants (malonic acid, sodium bromate and nitric acid), the polymer undergoes spontaneous cyclic soluble-insoluble changes or swelling-deswelling changes (in the case of gel) without any on-off switching of external stimuli. In this review, the design of self-motive nano-conveyer by arraying the micro-gel beads on surface and novel fabrication method —double template polymerizaiton— were summarized.

Capturing of acidic macromolecules from biological samples using a temperature-responsive polymer modified with poly-l-lysine.

We synthesized a temperature-responsive polymer, N-(isopropylacrylamide)-methacrylic acid copolymer, to which poly-l-lysine was introduced. The synthesized polymer as well as the parent polymer showed reversible soluble-insoluble changes in response to temperature changes across the lower critical solution temperature at 32 degree C in an aqueous solution. We found that the polymer efficiently captured acidic bio-macromolecules such as RNA, glycosaminoglycans and mucin-type glycoproteins in biological samples, and the captured molecules were recovered using aqueous NaCl solutions at high concentration. The target acidic molecules thus obtained will be employed for further studies such as structural analysis after brief desalting procedure. The proposed method does not require any chromatographic separations, but only needs a small volume of an aqueous salt solution for releasing captured molecules. Overall procedures are quite easy and simple, and are completed at least within 1 h. We show a few examples for capturing RNA and glycosaminoglycans from cultured cells using the polymer.

Self-oscillation of polymer chains with rhythmical soluble-insoluble changes.

Self-oscillation of polymer chains in an aqueous solution has been achieved. The ruthenium catalyst for the Belousov-Zhabotinsky reaction was polymerized by using N-isopropylacrylamide and dissolved into the solution containing the BZ substrates. Periodical soluble-insoluble changes of the polymer chain were spontaneously induced by the BZ reaction. The conformational oscillations of the polymer were measured as the optical transmittance changes of the solution. This is the first report that rhythmical and reversible soluble-insoluble changes of polymer chains are realized under constant and homogeneous conditions. The transducing system from chemical energy of the BZ reaction to optical information has been constructed.