Hybrid materials development

Figure 2 shows a comparison of nitrogen adsorption isotherms at 77 K for the organic-inorganic hybrid materials developed for adsorption of mercury ions. The shape of the nitrogen adsorption isotherms indicates that the mesostructure was preserved after chemical modification of the surface. Evaluation of the shift of the capillary condensation step and reduction of its height provide information about formation of the chemically bonded layer inside mesopores. 

I. 16 g mm /(m day) compared to 12.9 g mm /(m day) for the neat polymer (Yano et al., 1997). Theoretical modeling of this data shows that the variation in H O permeability and oxygen transmission rate (OTR) values, as a function of clay type, corresponds well to the natural platelet lateral dimensions for each clay. The first successful application of polymer-clay nanocomposites (PCNC) was a rtylon-6 MMT hybrid material developed by the Toyota Corporation in 1986 (Dastjerdi and Montazer, 2010). 

Clays have long been used as fillers in polymer systems because of low cost and the improved mechanical properties of the resulting polymer composites. If all other parameters are equal, the efficiency of a filler to improve the physical and mechanical properties of a polymer system is sensitive to its degree of dispersion in the polymer matrix (Krishnamoorti et ah, 1996). In the early 1990s, Toyota researchers (Okada et ah, 1990) discovered that treatment of montmorillonite (MMT) with amino acids allowed dispersion of the individual 1 nm thick silicate layers of the clay scale in polyamide on a molecular. Their hybrid material showed major improvements in physical and mechanical properties even at very low clay content (1.6 vol %). Since then, many researchers have performed investigations in the new field of polymer nano-composites. This has lead to further developments in the range of materials and synthesizing methods available. 

In the next section, we will highlight recent developments in the engineering of mesoporous and macroporous substrates via the LbL procedure to produce porous, hybrid materials for various bioapplications. 

Given the significant recent developments in the burgeoning areas of porous materials and self-assembly, we anticipate that, with further development, bioinspired porous hybrid materials will find their way into a range of therapeutic and diagnostic applications. 

Schiraldi et al. [64] have developed this kind of material by combining silica particles and pHEMA. pHEMA is a biocompatible hydrogel that has been widely studied in the past decades due to its chemical-physical structure and mechanical properties. It has been widely used in ophthalmic prostheses (contact or intraocular lenses), vascular prostheses, drug delivery systems and soft-tissue replacement [65]. These authors have shown that by incorporating silica nanoparticles, the resulting hybrid material is highly biocompatible and promotes bone cell adhesion and proliferation of bone cells seeded on it.1 ... 

Schiraldi, C., DAgostino, A., Oliva, A., Flamma, F., De Rosa, A., Apicella, A., Aversa, R. and De Rosa, M. (2004) Development of hybrid materials based on hydroxyethylmethacrylate as supports for improving cell adhesion and proliferation. Biomaterials, 23, 3645-3653. 

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