Synthesis And Properties Of Nanocomposites Based On Chitosan

The nanocomposites have at least one characteristic length scale that is of the order of nanometers. Due to the special properties, such as quantum size effects, small size effect and surface effect, nanocomposites show excellent properties compared with the bulk materials. As a natural polymer, chitosan intrinsically exhibits enticing properties such as biocompatibility, biodegradability, and aqueous adsorption capabilities. These properties make chitosan an ideal polymer for a wide variety of fields and industrial applications such as biomedical applications and the treatment of water pollution. Chitosan nanofibers have potential applications in specific textile. Furthermore, polymeric hollow nanospheres have attracted considerable research attention due to their large variety of applications in chemistry, biotechnology, and materials science. The advantages of polymeric hollow nanosphere include its encapsulation property, controllable permeability, and surface functionality. Therefore, the synthesis and property of nanocomposites based on chitosan will exhibit an attractive application prospect.In this paper, the synthesis and optical properties of one-dimensional (1-D) hybrid materials based on chitosan/titania (TiO₂) have been reported, and the chitosan/polyacrylic acid (CS/PAA) nanospheres containing silicon dioxide (SiO₂) cores and Eu-doped CS/PAA nanospheres have been also investigated.1-D hybrid materials based on chitosan/titania featuring fascinating fluorescence are reported in this paper. Chitosan and TiO₂ were dispersed using a single chemical species of NaOH solution. Surfactants have a key contribution to the growth of production. The anionic surfactant sodium dodecyl sulfate (SDS) is the best guide. The effects of reaction parameters, such as surfactant, reaction temperature and reaction time, on the morphology of the products were investigated. The growth mechanism of the 1-D hybrid materials was proposed. Photoluminescence (PL) investigation shows that the 1-D hybrid materials exhibit inspiring emissions under UV excitation, indicating that these nontoxic emissive 1-D nanomaterials may find use as fluorescent fabrics in the future.The hollow structure of polymeric nanospheres is spontaneously formed by polymerization of acrylic acid monomers inside the chitosan-acrylic acid assemblies. CS/PAA nanospheres were successfully prepared with acrylic acid and chitosan via this method. Firstly, chitosan was directly dissolved in acid solution, then initiator was added to initiate polymerization in N2 atomosphere. Finally, the surface of CS/PAA nanospheres was cross-linked by glutaraldehyde. Based on this, SiO₂ nanospheres were in-situ coating by CS/PAA. The morphology, dispersity and fluoresent properties of the products were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), fourier transform infrared (FT-IR) spectrometry, and PL. The formation mechanism of the products was simply discussed.Eu-doped CS/PAA nanospheres were successfully prepared. The CS/PAA nanospheres were formed by polymerization of acrylic acid and cross-linking of chitosan at the end of polymerization. Eu³⁺ was added in the reaction solution before the cross-linking of chitosan, and then the products were synthesized by adding glutaraldehyde as the crosslinking agent. The whole reaction process was described in detail. Fluorescence studies suggested that the characteristic peaks of Eu³⁺ was detected in the product, which greatly improved the fluorescence properties of CS/PAA nanospheres. Combine with the excellent biocompatibility of CS, Eu-doped CS/PAA nanosphere may have potential applications in biolabelling.