Vol.5 No.3 2012

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Research paper : Novel functional gels and their commercial distribution as chemical reagents (M. Yoshida)−182−Synthesiology - English edition Vol.5 No.3 (2012) and it is pointed out that “several breakthroughs have been achieved in functional gels investigations in Japan, and those have raised the level of the researches.”[2] Therefore, the important issues are how to increase the excellence of the core research level of Japan and how to develop the functional gel to practical industrial applications.While further advancement of functions is necessary to increase the excellence of functional gel development, the new materials must be mass-producible using a simple method, from the industrial perspective. From this perspective, the author embarked on problem solving from the synthetic chemical approach and engaged in new material manufacturing that realized the two points, achievement of novel function and simple synthesis. As a result, the “ionic gelator,” a material group that was totally unknown before, was originally developed. In this paper, the development process, efforts for the commercialization as a chemical reagent, and current issues will be explained.2 Process in the development of a new gelator and the research goalGels can be roughly divided into two categories, the chemical gels and physical gels, and each has its characteristics. For example, chemical gels generally have high elasticity and excellent dynamic property but are weak against strain, because the network structure of the gel is composed of the covalent bond. On the other hand, with physical gels, because the network structure is stabilized by the non-covalent bond interaction (such as hydrogen bond or - interaction), it is known that they undergo reversible sol-gel transition upon heating and cooling. The material showing the physical gel forming property is normally called a “gelator,” and both the natural-occurring and artificial gelators are used industrially. Table 1 lists the characteristics of the two gelators. The natural gelators, the most well known being agar and gelatin, are highly safe, are commercialized as food additives to add starchiness, and are available at a reasonable price. However, it is known that there is restriction in the gelation, such as the acidity of the solution must be neutral, and it is not usable in acid or alkali conditions since disintegration occurs. Also, since it does not dissolve in ordinary organic solvents, there are extreme restrictions in the gelatable solvents.[3] On the other hand, for the chemically synthesized artificial gelators, it is possible to add various functions unseen in natural gelators, by appropriate structural control and functional group introduction. However, multiple steps are usually necessary for the synthesis and refining processes of the artificial gelator. Therefore, unless a certain yield can be obtained at each step, the total yield would be low. Also, the isolation process such as column chromatography that uses large amounts of organic solvents may be inappropriate for large-scale production. As a result, although active R&Ds are done at the academic level, in most cases, the scale of synthesis remains at the laboratory level (with only a few grams of yield at most). In addition, there have been few researches on “amphiphilic gelators” that gelate in both water and organic solvents, and the gelation of multiple solvents with one gelator has been a major challenge.The author first became involved in gel material research by coincidence, as an extension of the research of dendritic polymer called the dendrimer, during the two-year study in the United States from 2002. The material used at the time was a system that was not suitable for mass production because multiple steps were required for synthesis. Also, the gelatable solvent was limited to only the organic solvent, and gelation was impossible for water that was the most common solvent (liquid). Upon returning to Japan, the author started research to develop a new material with a gelation function that could be manufactured using a commercially available starting material and which involved as few number of steps as possible, as well as the synthesis technology that was suitable for mass production and commercialization.[4]-[7]3 Molecular design as synthesiology: Use of organic electrolyte as a gelatorFrom the chemical perspective, a new material is a new molecule, and one of the optimizing methods to achieve the new molecular design and synthesis is a way of “synthesiology.” In that sense, the author paid attention to physical gelators in which the gel formation is possible through relatively weak interaction. The spontaneous aggregation of the molecules during gel formation and the formation of three-dimensional network structure are phenomena that are drawing attention in the current nanotechnology fields, as the “self-organization” of synthetic molecules. It is thought that gels with diversity from both the structural and functional aspects can be developed if this self-organization can be finely controlled. Also, the physical gelator can dramatically alter the viscosity of the basic solvent at extremely small amounts like a catalyst during a reaction, while maintaining the basic physical property of the solvent. Therefore, if gelation that could not be accomplished Table 1. Types of gelators and comparison of characteristics・In general, synthesis requires multiple steps; manufacturing process design is necessary for mass-production・Only a few types of solvents can be used・Unstable in acid condition・Unsuitable for gelation in solution other than water・Addition of function by chemical modification is difficultIssues・Chemical modification is possible・Functions such as stimulus response can be added・Abundant basic research・Available at low cost・High biocompatibilityAdvantages・Absorbing material, separation chromatography, actuator, etc.・Utilization of biocompatibility in foods, drugs, etc.Usage・Various synthetic polymer gels, etc.・Agar, gelatin, etc.Examples of compoundsArtificial gelatorsNatural gelators

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