Thermal and Solvent-Resistant Properties of Organic–Inorganic Polymer Hybrids Having Interpenetrating Polymer Network Structure by Formation of Metal–Bipyridyl Complex

Abstract

ABSTRACT:Organic-inorganic polymer hybrids having IPN (Interpenetrating Polymer Network) structure were synthesized utilizing an in-situ method, which was the simultaneous formation of organic gel through metal-bipyridyl complex and silica gel. Metal-bipyridyl complex was used as a cross-linking point to prepare the organic gel. The properties of the polymer hybrids, such as solvent-resistant and thermal properties, were different according to the kinds and the weight of the used metal ions. Especially, thermo-responsive polymer hybrids could be obtained using iron (II)-bipyridyl complex as a cross-linking point in the silica matrix.KEY WORDS Organic-Inorganic Polymer Hybrids / Sol-Gel Reaction / In-Situ Method / Interpenetrating Polymer Network (IPN) Structure / Solvent Resistant Property / Organic-inorganic polymer nanocomposite materials have received a great amount of scientific and technological interests. [1][2][3][4][5] Organic-inorganic polymer hybrids have not only the properties themselves of organic polymer and inorganic material but also the unique properties, which results from mixing of organic polymer and inorganic material at a nano-meter level. For instance, organic-inorganic polymer hybrids have high transparency, 6 excellent solvent-resistance, 7 gas-barrier property, flame retardance, gas-selective property, 8 and so on. The sol-gel reaction of alkoxysilane is one of the most efficient methods for the preparation of organicinorganic polymer hybrids. The method comprises initial hydrolysis of the alkoxysilane and subsequent condensation and removal of solvent, resulting in the silica gel. 9 One of the advantages of the sol-gel techniques to prepare composite materials is that the reactions can be performed under ambient condition, while conventional melt fusion technique for silica glass requires high temperature.Organic-inorganic polymer hybrids have been prepared by utilizing the formation of covalent bonds between organic polymers and inorganic phases. [10][11][12] In our group, a large variety of organic-inorganic polymer hybrids has been prepared through the sol-gel reaction of alkoxysilane. The most common method is utilizing physical interactions such as hydrogen bonding, 13-15 aromatic, 16 and ionic interactions 17 between organic polymer and silica gel. Another method is an in-situ method, in which the polymerization of vinyl monomer and the sol-gel reaction of silica gel are carried out simultaneously. By utilizing this method, trans- † To whom correspondence should be addressed. parent polymer hybrids can be prepared even if there is no covalent or physical interaction between organic polymer and silica gel. For example, transparent polymer hybrids can be prepared by the simultaneous occurrence of the polymerization of styrene monomer and the formation of silica gel. 18 Recently, we succeeded in the preparation of transparent polymer hybrids utilizing new in-situ method (Scheme 1). 19 In this method, the cross-linking reaction of bipyridyl-containing polymer was carried out together...

Creative Synthesis of Organic–Inorganic Molecular Hybrid Materials

“…Although hydrogen bonds are versatile, the number of applicable polymers is limited. There are many interactions besides hydrogen bonds, such as π-π interactions, 53 ionic interactions, 5456 covalent bonds, 5761 CT complex formation, metal-ligand coordination, 62,63 CH-π interactions, 64,65 host-guest interactions 66 and more. All of these interactions are available for preparing hybrid materials.…”

“…In particular, in the presence of ruthenium salt, the cross-linking reaction of bipyridyl-containing polymer was carried out together with the sol-gel reaction of TMOS, and the obtained polymer hybrids had IPN structure. 62,63 Using polystyrene or poly(ethylene oxide) having bipyridyl groups, organic inorganic polymer hybrids could be prepared. Cross-linking was produced by coordination bonds between two or three bipyridyl ligands and one ruthenium ion.…”

“…The obtained polymer hybrids showed excellent solvent resistance because of the IPN structure. 63 Covalent Bonds. Covalent bonds are one of the most stable interactions between materials.…”

Synthesis and Characterization of UV-Induced Interpenetrating Polymer Network (IPN) Structure of Poly(urethane acrylate) (UA Polymer)/Silica Hybrids

“…The elaborated organic-inorganic polymer hybrids exhibited both organic and inorganic features. Furthermore, the novel properties such as superior transparency, 28 excellent solvent-resistance, 13,15,17,18 flame-retardancy, high gas-barrier property 19 and surface-hardness 14 are added due to the nanometer scale miscibility between organic polymer and inorganic materials. To prepare transparent polymer hybrids based on the sol-gel approach, 29 the affinity between organic polymer and inorganic oxide is necessary.…”

“…In addition, we recently reported the simultaneous IPN formation: Organic polymer gel was prepared in-situ during the formation of silica gel matrix from sol-gel process. 13,17 The in-situ IPN formation gave the transparent polymer hybrids by controlling the gelation rate between organic polymer gel and silica gel even in the poor compatibility between organic polymer and silica gel.…”