Sharif Digital Repository

In this thesis, nanocomposites based on magnetic graphene oxide and iron oxide nanoparticles coated with smart polymeric materials (by polymerization of monomers such as glycidyl methacrylate, acrylic acid, and N-isopropyl acrylamide) via Reversible Addition−Fragmentation Chain-Transfer (RAFT) polymerization were successfully synthesized. The combination of large surface area in nanoparticles and different functional groups in polymeric layers can give unique properties to nanocomposites. Therefore, we synthesized various smart nanocomposites with this perspective. After synthesizing these nanocomposites, smart magnetic nanoparticles were characterized by FT-IR, NMR, XPS, TGA, DLS, VSM, GPC,... 

Smart heat-sensitive polymers play a unique role in drug delivery systems due to reversible behavior in response to environmental changes, especially temperature changes. Among the heat-sensitive polymers, UCST polymers due to their specific behavior and very little-known polymers with this feature are the subject of many new researches. In the present study, New designed temperature-sensitive polymers with UCST capability based on acrylamide and vinyl acetate were synthesized. These copolymers were synthesized in different percentages of acrylamide by free radical polymerization in solution conditions. All polymers compounds were characterized by H-NMR, FT-IR, DSC and GPC measurements. The... 

In recent years, the tendency to use biodegradable and biocompatible polymer nanoparticles for drug delivery applications has been increasing, the reason for this being the possibility of precise control of the drug release rate, ease of use, and no need for external Surgery after the release of the drug, increases the therapeutic efficiency of the drug and reduces the side effects with its precise transfer. In this research work, drug carrier nanocomposites were prepared from polylactic acid (PLA), polyethylene glycol (PEG) and hydroxyapatite (HAp) and for the controlled release of ciprofloxacin (CIP). It was used to treat bone infections. The drug loading efficiency for nano-carriers was... 

In this work, a comprehensive dynamic model has been used for styrene emulsion polymerization in a semi-batch reactor to predict the evolution of product particle size and molecular weight distributions under non-isothermal condition. Method of moments has been applied for solving the population balance equations and the results are compared with the results obtained from finite-volume method as a precise technique. A sensitivity analysis respect to perturbation in initial values of various reagents, species and the reactor temperature has been performed to identify suitable manipulated variables for closed-loop control of the reactor. The detailed model is used to generate optimal feed... 

Heavy metals such as lead, chromium, nickel are considered as environmental pollutants. These substances are highly toxic and dangerous to humans and other organisms at low concentrations and many problems are caused by them. Chromium belongs to the group of heavy and toxic metals. Form 6-valent chromium for humans is considered a definite carcinogen and also creates other problems. One common method of chromium removal is chemical precipitation which caused a large volume of waste. Other methods such as ion exchange, solvent extraction, reverse osmosis and biological methods are used to remove chromium. Adsorption is another effective method with very few disadvantages compared to other... 

In the present thesis, intracellular fluid flows have investigated for study cell motions. It is due to firmly relation between the cell motion and these flows. Generally, the cell firstly adheres to a surface, then, moves forward with the effects of the internal fluid flows. In this study, the cell structure is invided to two general parts; the front part of the cell and the cell body. The front part of the cell plays a essential roles in the cell motion, however, the cell body is considered as a extra cargo that is carried by the front of the cell. Therefor, in the present modellings, the front part is only considered. Here, using four different models for the front part of the cell, many... 

A new technique for surface modification of flat sheet hemodialysis membranes has been investigated. This new strategy presents a dynamic surface modification for membranes in order to assess the hydrophilicity, antifouling, and biocompatibility effects of two functional monomers on dialysis membrane. PSF membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. Afterward, free radical polymerization combined with surface polymerization used to introduce acrylic acid and 2-hydroxyethyl methacrylate onto polysulfone membrane surface. Various monomer concentrations were selected to obtain an optimum condition. Field emission scanning electron microscope (FE-SEM),... 

Dissipative particle dynamics (DPD) is an emerging mesoscopic computational method in which the interparticle forces arise because of coarse-graining at the molecular level. In the asymptotic limit of large length scales, the governing equations of continuum are reproduced, as demonstrated in this work. This method of simulation has the capability of simulating larger order of time and space in compare with dynamic molecular method. One of the important applications of DPD is simulating the dilute polymer solution. In this project, we developed a general code to simulate dilute polymer behavior which consists of polymeric forces and different types of usual DPD boundary conditions. This code... 

In the present investigation, experimental design, synthesis and evaluation of Verapamil, Albumin, Immonuglubline G and Trypsin imprinted polymers and finally Albumin imprinted poly(dopamine) nano-layer were presented. A bimodal polymerization approach as a combination of precipitation and dispersion polymerization was taken towards producing 500 nm particles for verapamil imprinting purpose. In this case the imprinting factor was 2.17. In a challenge for producing spherical particles with predefined size and pore properties the hierarchical polymerization in packed beds, using porous silica particles (particle size ca. 40 µm) was developed, as well. The method resolving the problems... 

to achieve a stable elimination of colloidal suspended particles, polymer flocculants such as polyacrylamide and its derivative have been more used. To improve the performance of removing turbidity, reducing settling time, and better dewatering from sediments, hydrophobic styrene monomer copolymerized with acrylamide monomer. In this study the copolymer of acrylamide and styrene was synthesized by inverse emulsion polymerization, then this copolymer undergoes hydrolysis to form anionic groups on the polymer backbone. FT-IR, H NMR, and TGA analyses were carried out to investigate the structure of the copolymer. To evaluate flocculation, turbidity tests, zeta potential, and sedimentation rate... 

The purpose of this study is the implementation of multi-model predictive control (MMPC) approach for the co-polymerization system of methyl methacrylate - vinyl acetate. Simpler development of local models and controllers and also convenience of understanding the model and controller structure are the main reasons for using this approach. In the first step, RGA analysis has been used for pairing input and output variables. Then the performance of PI controller on the system has been investigated. For designing model predictive controller (MPC) the nonlinear model has been linearized at operational point and the controller has been designed in MPC toolbox of MATLAB software R2013a. In the... 

The separation ofacetic acids in binary water solutions hasbeenstudied using a reverse osmosis (RO) membrane. Thin film composite polyamide membrane is used in this study.Thin-film composite (TFC) membrane was prepared through the interfacial polymerization between m-phenylenediamine (MPD) and trimesoyl chloride (TMC) on the polysulphone support membrane.The solute permeation was carried out under applied pressure of 5 bar at 25°C. In this work the effect of various synthesis conditions on the membrane performance was investigated. Parametric studies were conducted by varyingconcentration of reactants, reaction time, curing time and curing temperature. By suitable combination of these... 

This thesis focuses on modeling, simulation and control of bulk polymerization of styrene in an autorefrigerated reactor where the generated heat is removed by heat of vaporization of the monomer. By means of two mathematical models for the kinetics of reaction, static and dynamic simulations were performed. For this purpose the equilibrium points were calculated using the steady state analysis, and then the reactor temperature was controlled at the unstable point using PI and adaptive generalized predictive controller (AGPC). In order to implement the GPC scheme a process model is required to provide the process output estimate over the prediction horizon. For this purpose an auto... 

In the present research the methods and challenges to ocular drug delivery have been investigated with more emphasis on ocular diseases that do not have any approved treatment. Periocular route is a promising alternative to the common routes of ocular drug delivery especially for treatment of posterior eye diseases. Based on barriers for efficient drug delivery to the eye, magnetic drug targeting revealed to be influential to eliminate some obstacles of this route which has not been worked before. It is hypothesized that the particles can pulled into the eye or will be trapped inside the sclera tissue or even if it is not happened, they can stay behind the sclera and magnetic force can... 

In the present study we examined the fabrication of electrospun polymer drug delivery system for the production of polymeric film containing Rizatriptan drug. Fabricated films were underwent X-ray diffraction and DSC tests to ensure that the drug is not in crystalline and amorphous form. And the results revealed the fact that the drug is fully dispersed in the polymer. pH changes in the aqueous phase is too low so that it enable the polymeric film to be suitable for use in oral administration. In-vitro assay for different combination of sublingual polymeric suggested that Rizatriptan film with 3% weight by volume and 30% by weight by volume of electrospun polymer PVP is the best combination... 

Lately, some investigators of polymer engineering group are working to do continuous polymer solution casting process, rather than batch process for flat sheet membrane production. For this, they use a doctor blade system but, they faced some problems during coating process. From experimental observations of the studied system, some inappropriate vorticities were seen. That’s why the system forms a non-uniform film of the solution. Air bubbling occurs at system exit which is undesirable as well. In this study simulation and optimization has been done for forming thin film in doctor blade system. COMSOL Multiphysics 4.3b was used in purpose of simulating which works on numerical finite... 

In this research UHMWPE/MWCNT nanocomposites with different concentrations of nanotubes (0.5, 1.5, 2.5, 3.5 wt %) were prepared via in situ polymerization using a novel Bi-supported Ziegler-Natta catalytic systems. Magnesium etoxide and Multi wall carbon nanotubes functionalized by hydroxyl groups were used as supports of catalyst. TiCl4 accompanied by triethylaluminum constituted Ziegler-Natta catalytic system. Preparation of catalyst and polymerization were done in slurry phase under the argon atmosphere. Support of catalyst on MWCNT was investigated using Fourier Transform Infrared Spectroscopy (FTIR). The results confirmed interaction between catalyst and hydroxyl groups on the surface... 

In this study three type of nanofiltration membranes were prepared from PVC for water softening; (i) asymmetric PVC nanofiltration membrane, and two different thin film composite (TFC) membranes: (ii) polyamide (PA)/PVC composite membrane (iii) poly vinyl alcohol (PVA)/PVC composite membrane. Asymmetric nanofiltration membranes were prepared by phase inversion. The effect of PVC concentration, solvent (THF) and additive (PVP) on morphology and performance were studied by scanning electron microscopy (SEM) and measuring pure water flux and salt rejection. Increasing PVC concentration decreased pure water flux and increased salt rejection. Adding tetrahydrofuran(THF) decreased the pure water... 

The usual method for determination of pure component parameters of SAFT-type Equation of State (EoS) is to fit them to experimental vapor pressure and liquid density data. Since high-molecular-weight compounds, like polymers, do not have a detectable vapor pressure, there is a need for a predictive calculation method for parameters of polymers and other complex compounds. In 2008, Tihic et al. proposed a Group Contribution (GC) method for estimating molecular parameters of PC-SAFT EoS. In this thesis, it is attempted to extend the suggested method of Tihic et al. by adjusting molecular parameters of PC-SAFT EoS for about 120 new non-associating compounds using experimental data extracted... 

Shape memory polymers have the potential to use in the field of biomedical applications. In this research, polyurethane structures have been synthesized based on the Diol mixtures, consisting of polycaprolactane diol (PCL-diol) and poly (lactic acid) diol (PLA-diol). Aim of reasearch is about evaluating poly (lactic acid) effect in structure of the polyurethane. At the same time, cellulose nanocrystals (CNC) have been added to polymer matrix to improve properties. The synthesis of acrylated polyurethane, included the synthesis of polyurethane acrylate prepolymer. Next, this prepolymer has been cured by adding the reactive diluent and some polyol. The cured systems were investigated, finally,...