Sharif Digital Repository

The synthesis of nanocomposites via in situ grafting polymerization due to its ability to produce polymeric materials with promising microscopic and macroscopic characteristics is becoming very attractive. In this paper, different poly(L-Lactide)-block-poly(ε-caprolactone) (PLLA-b-PCL) copolymers were in situ synthesized in the presence of modified titanium dioxide (TiO2) nanoparticles (mTNP) as the initiator and stannous octoate as the catalyst. The surface of TiO2 was modified by grafting aminopropyl trimethoxy silane to improve initiator efficiency. Copolymers with 90/10, 70/30, and 50/50 mass ratio of L-lactide/ ε-caprolactone and 5 wt% of mTNP (proportional to ε-caprolactone) were... 

Composite coatings of Hydroxyapatite (HA) with ceramics, polymers and metals are used to modify the surface structure of implants. In this research, HA/TiO2 composite coating was fabricated by electrophoretic deposition (EPD) on 316 stainless steel substrate. HA/TiO2 composite coatings with 5, 10 and 20 wt.% of TiO2, deposited at 40 V and 90 s as an optimum condition. The samples coated at this condition led to an adherent, continuous and crack-free coating. The influence of TiO2 content was studied by performing different characterization methods such as scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), corrosion resistance in simulated body fluid (SBF),... 

Titanium dioxide (TiO2) is an extensively used electron transporting layer (ETL) in n–i–p perovskite solar cells (PSCs). Although, TiO2 ETL experiences the high surface defect together with low electron extraction ability, which causes severe energy loss and poor stability in the PSC. In this study, a new intermediate layer consisting of gold nanoparticles functionalized with fully conjugated fullerene C60 derivative (C60-BCT@Au NPs) that enhances the interfacial contact at ETL/perovskite interface leading to a perovskite film with improved crystallinity and morphology is reported. Moreover, the studies demonstrate that the interface modification of the TiO2 ETL with C60-BCT@Au NPs... 

Biocompatible and biodegradable three-dimensional scaffolds are commonly porous which serve to provide suitable microenvironments for mechanical supporting and optimal cell growth. Silk fibroin (SF) is a natural and biomedical polymer with appropriate and improvable mechanical properties. Making a composite with a bioceramicas reinforcement is a general strategy to prepare a scaffold for hard tissue engineering applications. In the present study, SF was separately combined with titanium dioxide (TiO2) and fluoridated titanium dioxide nanoparticles (TiO2-F) as bioceramic reinforcements for bone tissue engineering purposes. At the first step, SF was extracted from Bombyx mori cocoons. Then,... 

In this research, an attempt was made to investigate the potential of nanophotocatalysts for treatment of hazardous wastewater streams. Titanium dioxide nanoparticles (as photocatalyst) were immobilized on a porous and low-density support called "perlite" using a very simple and inexpensive method. TiO2-coated perlite granules were used in a "Floating-bed photoreactor" to study the photocatalytic purification process of a typical wastewater polluted by furfural. The effects of initial concentration, catalyst mass/solution volume ratio, oxidant molar flow, residence time, and light intensity on process removal efficiency, and kinetics of the reactions were studied. SEM analyses showed a... 

In recent decades, utilizing of water-based muds (WBMs) in drilling oil and gas wells is ever increasing comparing to oil-based muds and synthetic-based muds due to the lower environmental issues. However, the main drawbacks with WBMs are rheological properties inefficiency and shale swelling which have caused attentions turn to improvement of WBMs’ rheological properties. In this study, the effects of various nanoparticles (NPs) namely titanium dioxide (TiO2), silicon dioxide (SiO2), and zinc oxide (ZnO) on improving rheological properties and shale recovery rate of a WBM sample at two temperatures (25 and 50 °C) were investigated. The concentrations of NPs in the base mud were set at 0.01,...