Polyionic dendrimer and hydrogel comprising same

Abstract

Provided is a hydrogel which comprises water as the main component at a high water content and has mechanical strength suitable for practical use and which exhibits high transparency and self-healing and shape-retaining properties. Also provided are both a material for the hydrogel and a novel polyionic dendrimer. A polyionic dendrimer which comprises a hydrophilic linear polymer as the core and polyester dendrons attached to both terminals of the linear polymer and in which cationic groups are bonded to the surfaces of the dendrons, said cationic groups being selected from the group consisting of guanidine group, thiourea group, and isothiourea group; a material for a hydrogel, which comprises the polyionic dendrimer and clay; and a hydrogel prepared using the material.

Description

TECHNICAL FIELD[0001]The present invention relates to a novel polyionic dendrimer. The invention also relates to a material for hydrogel that contains the polyionic dendrimer and clay minerals (i.e., clay) and a hydrogel obtained by including a great amount of water in the material for hydrogel.BACKGROUND ART[0002]Water is an essential component for living organisms on earth and it is regarded as a symbol of pureness and cleanness. 71% of the surface of earth is covered with water and 65% of a human body is composed of this simple yet fully active molecule. In nature, especially in a biological world, water plays an important role. As such, if a water-retaining material with high water retention rate is produced, it can be used as an important material having a positive effect on environment and broad spectrum of use. Until now, an attempt to produce a water-retaining material with high water retention rate was not so successful due to poor mechanical strength as easily expected. Ho...

AI Technical Summary

Benefits of technology

[0060]The invention is to provide a polyionic dendrimer in which cationic groups are bonded to the surface, and a hydrogel using the dendrimer.

[0061]According to the invention, a tough and transparent hydrogel which can contain at least 94% of moisture and is gellified only with noncovalent bond can be provided. Further, as such water-retaining material with high water content can be introduced with a protein without compromising its biological activity and there is no decrease in mechanical strength caused by introduction of a protein, the hydrogel of the invention is useful as a protein-containing hydrogel.

[0062]Further, as the hydrogel of the invention maintains a shape-retaining property even when it is immersed in an organic solvent like tetrahydrofuran, it has a characteristic of regaining the original shape even when it is dried and treated with water for re-gellation.

[0063]The supramoleucalr hydrogel obtained from the invention contains a dendrimer with a specific size. Thus, by modifying the polymerization degree of the linear polymer in the dendrimer core, generation of the dendron, and types of an ion present on the surface of dendron, molecular designing of a polyionic dendrimer with various size and shape can be made and it can be used as a component for the hydrogel. Thus, it allows designing of a broad range of physical properties. Further, the polyionic dendrimer of the invention can be easily synthesized. Further, as the hydrogel of the invention can be easily formed by simple mixing and stirring of a clay nano sheet and a polyionic dendrimer, and if necessary, a linear polymer having an ionic side chain like sodium polyacrylate (see, FIG. 1), heating or cooling cycle which is required for production of conventional polymer hydrogels is not necessary. Thus, it has a huge potential as a multi-purpose material that can be easily produced and is favorable from an environment point of view.

[0064]Specifically, the hydrogel of the invention has excellent characteristics that it has high water content (at least 94%), sufficient mechanical strength, excellent transparency, excellent shape-retaining property, anti-chemical property, and self-restoring property which guarantees regaining of the original shape after re-gellation, and it can maintain a physiologically active or enzymatically active protein and the like without altering the properties of the protein.

[0065]Further, as it is known that polyalkylene glycol, preferably polyethylene glycol, as a hydrophilic linear polymer which constitutes the core of the polyionic dendrimer constituting the hydrogel of the invention, and polyester which constitutes the dendron can be easily discharged from a human body or they are biologically easily degradable (Non-patent Documents 5 and 6), it is favorable from an environment point of view and also highly safe to human body. The clay nano sheet used for the hydrogel of the invention has, as a raw material, an inorganic minerals present in nature, and thus it is a safe material that is already widely used for cosmetics such as lotion, toothpaste, shampoo, a shower gel, and the like (Non-patent Document 7). Based on such facts, it can be said that the hydrogel of the invention is not only favorable from an environment point of view but also highly safe to human body.

Problems solved by technology

Until now, an attempt to produce a water-retaining material with high water retention rate was not so successful due to poor mechanical strength as easily expected.

The polymer hydrogel that is crosslinked by a conventional method of organic chemistry is an opaque and soft material with low strength and also it has no self-restoring property.

However, the water retention rate of these gels is only 90% and the mechanical strength decreases as the water retention rate increases.

As polymerization or crosslinking is required to produce conventionally known polymer hydrogels, it is necessary to perform a complicated process such as repeated heating or cooling cycle.

However, as the synthesis is very difficult compared to other polymers, it is not practically usable yet.

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