Cellulose Derivative And Lanthanide Complex Thin Film

Cellulose is the richest natural polymer in the world,and thus it can be regarded as a very important raw material for several purposes.It has wide applications in medical products because of exceptional structural and functional properties.Cellulose structure has hydroxyl groups?OH?that can be partially or fully reacted with the different elements to give derivatives with useful properties,such as cellulose ester and ether.Cellulose derivatives have been used for numerous public life applications.Hence must be non-carcinogenic,non-poisonous,biocompatible,and in no way injurious into the bioenvironment.Cellulose ether is the most broadly utilized cellulose derivatives in the food and pharmaceutical ventures,such as Carboxymethylcellulose?CMC?and Cationic cellulose?CC?.Cellulose ether has produced by replacing the hydroxyl groups with either alkyl or hydroxyl-alkyl groups.The chemical nature,amount,and distribution of the substituted group control properties such as solubility,thermal stability,colloidal adjustment,surface action,thermo plasticity,film attributes and biodegradation.Lanthanides atomic structure has 4f orbits,which make them show exceptional chemical and spectroscopic properties.Lanthanides narcotic materials are of great interest for the potential applications in the fields of catalysis and glow.Some lanthanide ions,such as Terbium(Tb³⁺)and Europium(Eu³⁺),have been widely utilized in luminescent tests and stains for atomic gathering and bio-molecular structure.Understanding the interaction of polymer and metal ions has huge significance regarding the potential applications in science and innovation.Electrostatic force and coordination are two major interactions between polymer and metal ions.Metal ions are easy to lose electrons to become ionized while there are pairs of negative charged polymers,so the electrostatic force is extremely basic among polymers and metal ions.At the same time,atomic structure of metal ions has empty orbits while the polymer had a group that provide pair electron,which will shape coordination bond.Previous studies have been confirmed carboxylate?COO-?group reacted with metal ions basing on coordination bonds,there are several type of coordination such as unidentate,simple chelating,bridging bidentate,and chelating tridentate.In the last years,many attempts have been done to assemble cellulose derivatives into polyelectrolyte multilayers?PEMs?film by polymer interfacial complexation such as,Layer by Layer?LbL?assembly based on electrostatic interactions.LbL assembly is an effective way to prepare thin film.Lb L assembled film shows various applications,such as optical filter,ion separation,corrosion protection,chemical and biological sensor,and drug delivery.Lb L assembly is considered to expand utilization of cellulose,but cellulose cannot be directly assembled to prepare thin film.Through chemical modification,cellulose can be fit Lb L assembly.Recently,polymeric complexes have been used as building blocks by Lb L assembly.A polymeric complex is a type of supramolecular aggregate based on different secondary interactions,which includes polymer-polymer complexes,polymer-metal complexes,and polymer-surfactant complexes.The LbL of polymeric complexes makes it simple to create micrometer thick films and easy to integrate more materials into the film,which is great for achieving various functionalities,for example,super-hydrophobicity,selfhealing,and others.In our study,the aim of this research work is introducing Ln ions into cellulose derivative film.First prepare CMC-Ln complex nano-particles which are negatively charged,and then nano-particles are Lb L assembled with CC positively charged.We prepared the CMC-Ln-CC complex thin film at two pH values,at pH 4 and pH 6.This thesis is divided to three parts.The first part of this research is about the preparation of CMC-Ln complex nanoparticles at pH 4 and pH 6.CMC contains many carboxylate and hydroxide groups,and can form polymer-metal complex with Ln ions basing on coordination.CMC-Ln complex nanoparticles were prepared by mixing CMC solution and Ln ion solutions with the same volume under strictly controlling the pH value and weight ratios.We applied UV–Vis spectra,The UV-visible spectra indicate that the nano-particles contain cerium ion.At pH 4 with the ratio 6.1 or at pH 6 with the ratio 4:1,the dispersed CMC-Ce complex nanoparticles can be prepared.At weight ratio is 6:1 and 4:1,three methods used to prepare CMC-Ce complexation;?i?directly mixing Ce³⁺ solution and CMC solution?M1?,?ii?dropwise addition of Ce³⁺ solution into CMC solution at rate of 1 m L/h?M2?,?iii?dropwise addition of CMC solution into Ce³⁺ solution at the rate of 1 mL/h?M3?.We applied dynamic laser light scattering?DLS?to measure the size and the size distribution of CMC-Ce complex nanoparticles.At pH 4 the average hydrodynamic diameters of M1,M2 and M3 were 610 nm,450 nm and,740 nm respectively,and pH 6 were 650 nm,350 nm,1150 nm respectively.The Zeta potential of CMC-Ce complex nano-particles at pH 4 were-21.2,-19.2,-20.6,and pH 6 were-43.7,-36.8,and-38.6 for M1,M2,and M3 respectively.As the pH value increases,the ionization will become strong and there will be more carboxylate groups available.The FTIR spectra used to determine the ionization degree of CMC.According to the calculation from Equation?1?,at pH 2 the ionization degree of CMC is about 15 %,at pH 4 is about 55 %,and at pH 6 is close to100 %.The separation between asymmetric and symmetric stretching vibration of COO-can reflect coordiantion between CMC and cerium ion.Also the type of coordiantion depend on pH and weight ratio.The second part is about the fabrication of thin film from oppositely charged.The negatively charged dispersed CMC-Ln complex nan-particles are Lb L assembled with positively charged cellulose derivatives CC.Two films were produced at pH 4 and pH 6 by the LbL technique,and their properties were studied by different spectroscopic techniques.Reflection spectroscopy applied to characterize films,The [CC/?CMC-Ce?]₃₀ film fabricated at pH 4 is very cloudy,there are no Fabry-Perót fringes and its thickness is hard to measure.The [CC/?CMC-Ce?]₃₀ film fabricated at pH 6 is transparent,and its thickness calculated with Equation?2?.The thicknesses of the thin film prepared at pH 6 at M1 and M2 are 1222 nm and 750 nm respectively however,the film produce of M1 is very weak.Among these three methods,the first method is recommended to prepare CMC-Ln complex colloidal particles for LbL assembly due to the film has excellent properties compared to other methods.Three kinds of Ln ions,Ce³⁺,Eu³⁺,and Tb³⁺ have been successfully incorporated into films,and hence the ternary complex thin films shows blue,green and red fluorescence respectively.In addition,we can adjust the luminescence color of the film by combination of three different CMC-Ln complex nano-particles with different content.Incorporation of Ln3+ ions could be further utilized to reduce the hydration degree of CMC in natural pH value,and improve the film thickness growth and stability on the substrate.Finally,the [CC/?CMC-Ln?]₃₀ assembly archived by electrostatic interaction,and CMC-Ln assembly based on coordination generate competition due to the difference in charge interaction.Hence the Lb L assembly of CC and CMC-Ln ions complex nano-particles results in a convoluted dynamic process.When the film was incubated in different environment,the force in the film change and the equilibrium shifted.On other side,Immersion the [CC/CMC]₃₀ films in CeCl₃ solution increase the absorbance to 8 hours then start to decrease.So immersion the [CC/CMC]₃₀ films in CeCl₃ solution leads to dissolve the film after 4 days.However incubation the [CC/?CMC-Ce?]₃₀ film into CeCl₃ solution increase the thickness of the film.So the best methods to fabricate film with metal ions are first prepared the complex then fabricate film by LbL.