Vol.5 No.3 2012

48/94

Research paper : Novel functional gels and their commercial distribution as chemical reagents (M. Yoshida)−183−Synthesiology - English edition Vol.5 No.3 (2012) before in a certain solvent system becomes possible through the development of a new gelator, it is expected to expand the gel application further.The author’s thoughts on the guideline for the specific molecular design of a new material are shown in Fig. 2.In this research, we focused on the “organic electrolyte compound.” Hydrogen bond between the functional group and hydrophobic interactions are generally known as the intermolecular interactions that act as the driving force of molecular self-organization, and are actually used in the gelator system (Fig. 2 “Conventional gelator”). On the other hand, the self-organization of organic electrolyte compounds that easily combine the interactions is actively investigated from the perspective of biology, in extremely complex natural systems such as the double helix structure of DNA and its further hyperaccumulation. However, the self-organization in the artificially synthesized organic electrolytes had not drawn much attention compared to the neutral compounds. In the preparation of hydrogel where the solvent is water, it is important for the gelator to have both the hydrophilic and hydrophobic sections to be amphiphilic. For conventional gelators, the hydrophilic property was mainly borne by the corresponding functional groups such as the hydroxyl group or the carboxyl group. On the other hand, the characteristic of organic electrolytes as represented by various ammonium salts is to show hydrophilic property due to the salt structure (cation and anion in pair) of the molecule, even without the functional groups. We set this nature as an important element of the molecular design. While the polymeric electrolytes are expected to be applied widely to the electrolyte and separation membranes of batteries, we expected the gelation would occur by incorporating a functional group capable of interaction to such organic electrolytes, and then oligomerizing to add multiple functions (lower part of Fig. 2). As a method to easily achieve this new concept, the one pot self-condensation reaction (reaction that takes place in one flask only, where the molecules spontaneously condense to gain relatively high molecular weight) that used commercially available starting materials was devised, as shown below. As a result, the synthesis of new organic electrolyte with oligomeric structure with a gelation property (electrolyte gelator) was established (Fig. 3).It was found that this material actually possessed various characteristics including: 1) acid resistance, 2) solvent compatibility, 3) self-healing property, 4) complexation with carbon nanotubes, and 5) antibacterial property. These comprise the main points of synthesiology, as “functions that occur in the appropriate molecular design.” The details will be explained in the following chapter.4 Property of the electrolyte gelator (ionic gelator)4.1 SynthesisThe polymer with a quaternary ammonium structure in the main chain is called the ionene polymer, and this is normally synthesized by the copolymerization of two monomers, diamines (nucleophilic) and dihalogen compound (electrophilic). We thought the synthesis of the new functional organic electrolyte compound would be possible by the molecular design of an amphoteric monomer with a rigid structure, where the electrophilic and nucleophilic sections coexist within a molecule, and in which intramolecular quaternization reaction will not occur. Based on this strategy, as shown in Fig. 3, we conducted synthesis by chemical reaction involving the mixing of two types of reagents (4-aminopyridine and 4-chloromethylbenzoic acid chloride) that were purchasable as chemical reagents, in Fig. 2 Molecular design for new gel materialDeveloped electrolyte gelatorConventional gelatorSelf-organization (gelation)Solvent moleculeSolvent moleculeCompositionAmmonium salt as hydrophilic partDifferent functional group in place of hydrophobic part

※このページを正しく表示するにはFlashPlayer9以上が必要です