Study On Synthesis Of Ferrocene-Based Esters,Amides And Methacrylate Polymers And Their Anti-Migration And Burning Rate Catalytic Properties

Rocket design and its production is perceived as a significant research aspect in aerospace and defense industry.Most extensively used rockets are equipped with composite solid propellants.Composite solid propellants provide driving force for rocket propulsion and most of these composite solid propellants contain hydroxyl-terminated polybutadiene(HTPB)and ammonium perchlorate(AP)as their primary ingredients.The topmost element in rocket design is the burning rate of the propellant An excellent composite solid propellant should have a low pressure exponent and a very stable burning rate.To get such characteristic,the best way is the addition of a burning rate catalyst to the composite solid propellant.The use of burning rate catalysts(BRCs)in solid propellant facilitates smooth burning rate,improves ignition performance,eliminates primary smoke,and reduces sensitivity to temperature and pressure.Ferrocene-based derivatives display a higher catalytic activity due to their microscopic homogeneities in distribution,excellent ignitability in the propellant and higher compatibility with organic binder.Therefore,ferrocene-based derivatives are the most effective and widely accepted BRCs in AP-based composite solid propellants.However small ferrocene-based derivatives as BRCs have some intrinsic drawbacks,such as their migration to the surface of the solid propellant in long-time storage and sublimation or evaporation loss during processing.Migration makes the propellant burn unevenly and reduces its anti-aging ability due to formation of highly sensitive boundary layers Furthermore,migration affects the pourability of the propellant to a large extent.Migration increases the mechanical sensitivity toward pressure and temperatures and also changes the designed burning parameters of the propellant.To overcome these migration problems,much attention has been paid to improve the effectiveness and efficiency of ferrocene-based BRCs.The migration problems can be overcome by extending length of carbon chain on ferrocene ring,introducing polar elements like oxygen and nitrogen which make ferrocene-based BRCs polar,introducing reactive groups in ferrocene ring such as epoxide,OH,NH2,NCO,etc.,introducing inorganic groups in ferrocene ring and synthesizing high molecular weight ferrocene-based dendrimers.In our research,we have synthesized different ferrocene-based BRCs.It was found that the presence of oxygen and nitrogen in the ferrocene-based BRCs made them polar,which resulted in the dipole-dipole interactions between ferrocene-based BRCs and AP.The formation of strong hydrogen bonding and dipole-dipole interactions in the synthesized ferrocene-based BRCs resulted in excellent anti-migration properties.These ferrocene-based BRCs also exhibited high catalytic effects on the thermal degradation of AP.1)Ferrocene-based hydroquinone compounds(HQ-Fcs)were synthesized as BRCs.The structures of these synthesized HQ-Fcs were characterized by proton nuclear magnetic resonance(1H NMR)and Fourier transform infrared(FT-IR)spectroscopy.The electrochemistry of HQ-Fcs was examined by cyclic voltammetry(CV).The CV experimental results indicated that these HQ-Fcs showed good electrochemical performances,which were contributable to their catalytic activity in composite solid propellants.Anti-migration studies confirmed that the migration of HQ-Fcs was much slower than most commonly used ferrocene-based burning rate catalyst,2,2-bis(ethyl ferrocenyl)propane(catocene).Thermal stability and burning rate catalytic effect of HQ-Fcs on the thermal decomposition of AP was investigated by thermogravimetry(TG)and differential thermogravimetry(DTG)techniques.According to TG-DSC experimental results.these HQ-Fcs exhibited high catalytic effects for the thermal degradation of AP.2)Ferrocene-based aminopyridine(AP-Fcs)and aminothiazole compounds(AT-Fcs)were synthesized as ferrocene-based BRCs.The successful synthesis of AP-Fcs and AT-Fcs was confirmed by 1H NMR and FT-IR spectroscopy.The electrochemical properties of AP-Fcs and AT-Fcs were analyzed by CV.All the ferrocene-based compounds showed higher oxidative abilities.The anti-migration studies of AP-Fcs and AT-Fcs displayed low-migratory ability in the migration test.The anti-migration performance of AP-Fcs and AT-Fcs were found to be better than catocene and ferrocene.Catalytic behavior of AP-Fcs and AT-Fcs on thermal decomposition of AP were investigated by TG and DTG techniques.It was found that almost all the synthesized compounds were thermally stable and have high catalytic activity for the thermal decomposition of AP.3)Three different copolymers of poly(2-(methacryloyloxy)ethyl ferrocene carboxylate-co-glycidyl methacrylate)s(P(FHEMA-co-GMA)s)were synthesized by free radical polymerization of FHEMA and GMA.The successful synthesis of P(FHEMA-co-GMA)s was confirmed by 1H NMR and FT-IR spectroscopy.The electrochemical properties of P(FHEMA-co-GMA)s were analyzed by CV.CV results indicated that P(FHEMA-co-GMA)s showed redox processes which were diffusion controlled over the investigated scan rate range.Anti-migration studies of P(FHEMA-co-GMA)s was found to be excellent due to the formation of integrated network structures.Burning rate catalytic activity of P(FHEMA-co-GMA)s was evaluated by investigating its catalytic effects on the thermal degradation of AP using TG and DTG techniques.The results showed that these copolymers have excellent catalytic activity.4)A series of copolymers of poly(2-(methacryloyloxy)ethyl ferrocene carboxylate-co-methacrylic acid)s(P(FHEMA-co-MAA)s)were synthesized as BRCs.The structures of P(FHEMA-co-MAA)s were confirmed by 1H NMR and FT-IR spectroscopy.The electrochemical behavior of P(FHEMA-co-MAA)s was investigated by CV.The CV results indicated that P(FHEMA-co-MAA)s showed redox behavior and it was also observed that the shape and the peak values of CV curves were affected by the solvent polarity and potential scan rates.Anti-migration test proved that P(FHEMA-co-MAA)s possesses better anti-migration properties than ferrocene and catocene.P(FHEMA-co-MAA)s were found to have good catalytic activity for accelerating the thermal decomposition of AP.