No abstract

Modern optoelectronic devices based on hybrid nanocomposite thin films composed of inorganic colloidal quantum dots (CQDs) embedded in an organic conjugated polymer have attracted much scientific attention. The CQDs are solution phase processed nanostructure which are coated with a surface ligand material that is comprised of short, organic molecules to prevent the CQDs from aggregation when placed in solution. These surface ligand materials behave as a thin, insulating layer that has been shown to prevent efficient transfer of excited carriers into and out of the CQD. Therefore, it is important to understand the effect that the surface ligand material has on the optical properties of the nanocomposite materials in order to design more efficient hybrid nanocomposite optoelectronic devices. In this paper, we present a method for calculating the electronic structure such as intraband energy levels and wave functions for CQDs in a nanocomposite thin film structure. The model is verified by comparing the results to reported data in literature. The model which is based on matrix method, causes simplicity in calculation and can easily be applied for more complicated structures.

Polymeric nanostructures for drug delivery applications including smart hydrogels and stealth micelles have been developed to overcome many obstacles in the way of timing and targeting the delivery to fulfill therapeutic potentiality of chemicals. The purpose of this investigation is to prepare and characterize novel nanoparticle-based colloidal products composed of biocompatible polymers to use for rate-controlled release and targeted/spatial drug delivery systems, aiming specifically at drug delivery via mucosal routes. We formulated the new products with inert and biocompatible polymers including sodium carboxymethylcellulose (NaCMC) and polysorbates. The synthesis process was performed by heating/cooling method, as a type of physical cross-linking method for producing hydrogel, in three steps to optimize physical and chemical characteristics of the products to make them suitable for delivery through mucosal routes. A series of nanoparticle-based colloidal products in the form of liquid suspensions were developed, and from all three steps, thirty-nine samples were selected and rheologically investigated by bench-top experiments. A freeze-thawing method was applied to two samples of product III10 for five and one repeated cycles sequentially. Test tube inversion method was also carried out on all the produced gels. Most of the products are new types of temperaturesensitive, smart, physically self-assembled hydrogels and took the forms of sol, gel (opaque and transparent), and precipitate. However, these hydrogels show opposite gelation property to customary temperature-sensitive gels. The product of five repeated freezing-thawing cycles is also thermoreversible gel with a high mechanical stability and swelling capacity, as opposed to the product of one cycle. Some types of produced hydrogels behave like a ternary system. The products of this work, with microstructure consisting of the polymeric chains of sodium carboxymethylcellulose and a large-scale self-assembly of micellar structures of polysorbates incorporated within a polymer network, show major efficacy of site-specific and controlled release drug delivery system.