Preparation and characterization of poly(tetramethyl- p -phenylenediamine)/clay hybrids via intercalative polymerization
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Nobuo Iyi and Taketoshi Fujita Advanced Materials Laboratory (AML), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan (Received 26 October 2002; accepted 19 November 2002)
New noncovalent bonding polymer/clay hybrids were prepared, including the polymer poly(tetramethyl-p-phenylenediamine) (poly-TMPD). Polymerization occurred in the interlayer space of clay mineral successively after intercalation of monomers. Two types of clay minerals with different surface properties—a hydrophilic lithium fluorotaeniolite (TN) and four kinds of organophilic fluorotaeniolites (org-TNs)— were used as the hosts. Powder x-ray diffraction results showed an increase of 0.7–1.0 nm in the basal spacings, indicating the formation of poly-TMPD in the interlayer space of the hosts. Intercalative polymerization was also supported by Fourier transform infrared spectroscopy. The orientation of the poly-TMPD and thermal behavior were also discussed. I. INTRODUCTION
Organic/inorganic hybrids have received substantial current interest because they integrate the advantages of organic with inorganic materials or even show unexpected physical and chemical properties.1,2 For example, polymer/clay nanocomposites exhibit unusual and better physical properties (mechanical, thermal, and gas barrier properties, etc.) when compared with their parent organic or inorganic materials.3–5 In situ intercalative polymerization, i.e., intercalation of organic monomers followed by polymerization in the interlayer space of layered materials, is an effective way to construct organic/inorganic hybrids. Up to now, many hybrids, such as nylon 6/clay6 and polystyrene/clay7 and poly(methyl methacrylate)/ clay8 nanocomposites, have been successively obtained by such a procedure. Layered silicate is one of the most important materials suitable for designing desired organic/inorganic hybrids due to its unique properties, such as cationic exchange ability, swelling property, and large specific surface area.9 Lithium taeniolite (TN) belongs to 2:1-type clay mineral consisting of negatively charged silicate layers and readily exchangeable interlayer cations, Li+. After ion exchange with certain organic cations, such as
alkyltrimethylammonium, the basal spacing is enlarged and the hydrophilic surface of TN is changed into organophilic TN (org-TN). Aromatic diamines have been studied in the fields of photophysical and photochemical processes,10,11 trace analysis of metal ions,12 and amperometric biosensors,13 mutagenicity,14 etc. Tetramethyl-p-phenylenediamine (TMPD) is an important aromatic diamine that forms radicals and can be photo-oxidatively polymerized at ambient temperature in the air.15–19 Shao et al.19 has incorporated poly-TMPD into MoO3 to construct a polymer/ MoO3 layered structure. Such types of poly-TMPD/ layered inorganic hybrids have potential applications in the fields of material chemistry, such as conducting materials. However, the study of in situ intercalative polymerization of TMPD in layered materials is very l
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