Natural, silicone and polyurethane rubbers are considered as three important biomaterials which have found widespread applications in medical technology. Biocompatibility, biodurability, sterilisability, processibility, as well as mechanical properties, such as flexibility and resilience, are properties that make these kinds of rubbers appropriate candidates for medical applications. Medical devices based on natural rubber, silicone and polyurethane rubbers include cardiac pacemaker leads, mammary prostheses, artificial skin, catheters, denture liners, diaphragms, blood pressure cuff coil, tubes and seals. These types of rubbers are commonly used in controlled drug delivery systems as a carrier for pharmaceutical agents and in the fabrication of other medical devices. These polymers were evaluated for release of hormones (e.g. estradiol and progesterone), metronidazole, nonoxynol-9, etc. In this paper, some recent advances on the development of these polymers in the biomedical field and some reports on the modification and improvement of their properties such as drug release and mechanical properties are reviewed.

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Organic−inorganic nanocomposite protective coatings were prepared by sol−gel method using 3glycidoxypropyl-trimethoxysilane (GPTMS), tetramethoxysilane (TMOS), or tetraethoxysilane (TEOS) as silane precursors to compare the effect of two types of alkoxysilane (i.e., methoxy or ethoxy functional group) on aluminum substrate properties. In addition, the TiO 2 and AlOOH nanoparticles were derived from tetra-n-butyl titanate and aluminum butoxide, respectively, and the protective effect of these nanoparticles on the GPTMS based coatings was investigated. The formation of AlOOH and TiO 2 nanoparticles and the uniform distribution of nanoparticles in the coatings were characterized by dynamic light scattering (DLS) and different microscopic techniques. Potentiodynamic scanning (PDS) and 2000 h salt-spray testing methods were used to investigate the corrosion resistance of these hybrid sol−gel coatings. The PDS results demonstrated that the corrosion protection of hybrid coatings depends mainly on the silane content, type of the silane precursor, and type of nanoparticles. The coating protective effect improved by increasing polarization resistance (Rp) for about one decade by replacing silane precursors from TEOS to TMOS. In addition, the incorporation of TiO 2 in comparison with AlOOH nanoparticles in the GPTMS based coatings showed improving effect on polarization resistance. However, the simultaneous incorporation of TiO 2 and AlOOH nanoparticles led to high protective coatings.

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Smart corrosion-inhibiting coatings generate or release an inhibitor only when demanded by the initiation of corrosion. Supramolecular nanocontainers of the α-cyclodextrin (α-CD) corrosion inhibitor were prepared by inclusion complex (IC) formation between α-CD and 2-mercaptobenzothiazole (MBT) or 2-mercaptobenzimidazole (MBI) under various conditions (at room temperature and under sonic energy). The structure of the supramolecular nanocontainers was characterized by hydrogen nuclear magnetic resonance ( 1 H-NMR), x-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR). Supramolecular nanocontainer formation between MBT and MBI with α-CD in solid phase was emphasized by the significant differences between the 1 H-NMR, FTIR and XRD spectra of the physical mixtures with respect to those of the complexes. The crystalline complexes adopted a head to head channel-type and cage conformation for α-CD/MBT and α-CD/MBI inclusion complexes, respectively.

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