New Approaches To Hybrid Ferrocene-Cyclophosphazenes With Their Mechanistic Chemistry And Performances

The field of polyphosphazenes is a very broad one that had its origins in small molecule chemistry begun in the early 1800’s,but the polymeric aspects have been developed mainly during the past 35 years.It is a field that has involved research carried out worldwide,with the involvement of inorganic,organic,organometallic,physical,and polymer chemists together with engineers,materials scientists,and medical researchers in academic,government laborites and industry.This dissertation is organized into four chapters.Chapter 1 covers underlying concept,historical background and mechanistic approaches towards the polyphosphazenes.It also deals in some detail with the ways in which small molecule polyphosphazenes are used as models and starting points for more challenging work with high polymers and cross-linked polymers.Thus,this section provides the background and general principles that should be valuable to readers who are newcomers to polyphosphazene chemistry.Chapter 2 describes for the first time a high-throughput preparation of crosslinking poly(cyclotriphosphazene-co-bis(aminomethyl)ferrocene)hybrid microspheres.The mean diameter of the microsphere varies from 0.3-1.3 μm,depending on the concentrations of both monomers(hexachlorocyclotriphosphazene(HCCP)and 1,1’-di(aminomethyl)ferrocene(FDA))in a calculated molar ratio.When the concentration of HCCP was changed(0.50,1.0,2.0 mM),the diameters of microspheres were in the micrometer range and,varied from 0.5-1.3 μm,while the other monomer concentration was kept constant(6.0 mM).Similarly,when the concentration of FDA was changed(7.0,8.0 mM),the diameters of microspheres varied from 0.3-1.0 μm,while the other monomer concentration was maintained constant(1.0 mM).It can be concluded that with the increase of monomer concentrations in a calculated molar ratio,the size of the microspheres increased gradually,which provides more evidence to explain the absorbing mechanism of the oligomer species.The morphology and structure of microspheres were characterized by FT-IR,SEM,EDX,elemental mapping,BET and TEM analyses.The synthesized materials were tested for various properties such as thermal stability,fluorescent,electrochemical and magnetic properties.These microspheres were found to be an excellent high capacity adsorbent for the selective organic cationic dye and anionic dye,methylene blue and methyl orange,respectively,removal from contaminated water.Chapter 3 deals the preparation of cross-linked poly(cyclotriphosphazene-co-bis(methaoxy)ferrocene)nanofibers decorated with silver nanoparticles and characterized well by various techniques.The results prove that silver nanoparticles have been completely dispersed on the surface of nanofibers showing excellent thermal stability.When the concentration of HCCP was 2.0 mM,the diameter of nanofibers varied from 50-55 nm while the other monomer concentration was 3.0 mM.Similarly,when the concentration of HCCP was 1.0 mM while the concentrations of 1,1’-ferrocenedimethanol were 3.0 and 6 mM,the average diameter of nanofibers varied from 25-30 nm.It can be concluded that with the increase of monomer concentrations in a calculated molar ratio,the size of the nanofibers increased gradually.We also examined the catalytic performance of nanofibers with silver decorated for the reduction of 4-nitrophenol into 4-aminophenol in the presence of sodium borohydride with more than 90%conversion.Chapter 4 covers the biomedical application of highly porous cross-linked polyferrocenylphosphazene hybrid microspheres and results confirm that these highly porous hybrid microspheres contain good biocompatibility and dispersibility in both inorganic and organic solvents.For designing the high porosity on the surface of microspheres,we have developed a system of solvents that led to double diffusion.The microspheres were completely dispersed in the minimum amount of the DMSO as a solvent using ultrasonic irritation for 30 min and hanged in the chloroform and then made airtight to obtain highly porous microspheres.Additionally,the microspheres have high ability drug storage and excellent sustained release property of doxorubicin hydrochloride.It can be observed that up to 78%of DOX released into the buffers at pH 7.4 after 10 days.In contrast,at pH 4.4,about 58%of DOX already released into the buffers after 10 days.HPFc microspheres would be able to sustain most of the immersed DOX from releasing within 10-12 days and thus avoid significant damage to normal tissues during a delivery procedure.The capacities these microspheres for drug storing are 406 mg g-1.