Study On Synthesis Of Ferrocene And Azobenzene-based Copolymers And Their Redox And Photo-responsive Properties

Information storage materials are playing an increasingly important role in our daily life,and in both industrial and academic communities.Among different storage materials,redox and photoresponsive polymeric materials are the promising candidates for this purpose.These materials have good fast,clean and effective response properties.The introduction of a redox-responsive group into a polymer system containing a photoresponsive group provides a good information storage material.Ferrocene being a material with 18-e structure is considered suitable for information storage in comparison with its neighboring late-transition-metal neutral metallocenes such as manganocene(17-e)and cobaltocene(19-e).The robust isoelectronic 18-e ferrocene-type structures provide high thermal stability,solubility in common organic solvents,stability in air and mild/reversible redox.Likewise,photoresponsive polymers are also an important system for stimuli response and their properties can be modulated according to the requirements.Azobenzene is considered as one of the better and extensively used photo responsive compound due to its structural modifications which depends on the specific wavelength of light.What is noteworthy that femocenyl center can affect the isomerization behavior of the azobenzene.Storage devices which are constructed from small molecules having redox and photo responsive groups usually suffer from several problems such as stacking,weak mechanical strength,inappropriate photo stability and so on.It is important to develop novel ferrocene and azobenzene-based copolymers for the fabrication of new information storage materials.In our research,we synthesized different ferrocene and azobenzene-based copolymers,and their redox and photo responsive properties are deeply analyzed.1)The demand of novel information storage materials is increasing day by day.Ferrocene and azobenzene-based copolymers can serve well for this purpose.Three different copolymers(poly(2-methacryloyloxy ethyl ferrocene carboxylate-co-(methacryloaminoazotoluene)s)(P(FHEMA-co-MAAT)s)were synthesized using free radical polymerization and the redox and photo responsive behavior of ferrocene and azobenzene-based copolymers were analyzed.The copolymers were characterized by proton nuclear magnetic resonance(1H NMR)spectra and molecular weights were determined by gel permeation chromatography(GPC)analysis.Thermal stability of the polymers was confirmed using thermogravimetric/differential thermogravimetric(TG/DTG)and differential scanning calorimetry(DSC)analysis.The synthesized polymers showed good thermal stability due to the inclusion of electron donating groups on benzene rings.The resulting copolymers showed excellent redox and photoresponsive properties which were confirmed with the help of cyclic voltammetry(CV)and ultraviolet-visible(UV/vis)spectroscopy.It was concluded that when these moieties were combined together,they showed very good electro-photo responsive behavior which can be further used for information storage application.2)Three different copolymers(poly(2-methacryloyloxy ethyl ferrocene carboxylate-co-methacrylo hydroxyl hexane azobenzene)s)(P(FHEMA-co-MAZOHE)s)were prepared by introducing azobenzene with longer alkyl chain,and characterized by 1H NMR spectra and GPC results.A longer alkyl chain with azobenzene was introduced to possibly affect the properties of the copolymers.Thermal analysis was performed by TG/DTG and DSC techniques.Redox-responsive behavior was analyzed by CV curves while the reversible photoisomerization was determined by UV/vis spectra.The results exhibited that less polar solvents such as DCM and low scan rates are more favorable for the redox reactions.On the other hand,copolymers also showed reversible light-responsive behavior.Subsequent irradiations of UV and visible light showed that the copolymers were responsive to the specific wavelengths of lights.All these characteristics showed that when these moieties were combined together,the polymer provided very beneficial redox/photo responsive behavior and is a potential information storage materials.3)Three different copolymers(poly(2-methacryloyloxy ethyl ferrocene carboxylate-co-methacrylo-4-aminoazobenzene-co-methacrylicacid)s)(P(FHEMA-co-MAZO-co-MAA)s)were synthesized by introducing methacrylic acid units,and their redox and photoresponsive properties were analyzed.The synthesized copolymers were characterized by1H NMR spectra and GPC results.Thermal studies were performed by TG/DTG and DSC analysis which showed that the copolymers were thermally stable under operating conditions of the information storage devices.Redox studies and photoresponsive studies were performed by CV technique and UV/vis spectroscopy which showed that these copolymers have good redox and photoresponsive properties.The obtained results indicate that the obtained polymers have a prospect for use as an information storage material.4)Three different copolymers(poly(2-methacryloyloxyethyl ferrocene carboxylate-co-methacrylodisperseorange-3-co-methylmethacrylate)s)(P(FHEMA-co-MDO-co-MMA)s)were synthesized by introducing methyl methacrylate and thoroughly characterized by 1H NMR spectra.Molecular weights of the copolymers were obtained by GPC results.Thermal analysis was performed by TG/DTG and DSC techniques while CV and UV/vis spectroscopy were adopted for the study of redox and photoresponsive behavior.The UV/vis studies showed that reversible isomerization of the polymers was very good,which was possibly due to the addition of methyl methacrylate which helped to enhance the free volume available for the isomerization.Similarly,the redox results obtained from CV show that the copolymers have good redox properties.P(FHEMA-co-MDO-co-MMA)s have prospects for use as information storage materials.