Micro Plasma Technique For Fabrication of Functional Silver Polymer Nanocomposites

Abstract

Metallic Nanocomposites were produced at room temperature, atmospheric pressure, and micro-plasma technique. In this experiment silver (Ag) Nano-particles were made by means of silver nitrate as a precursor. Stainless steel capillary tubes act as cathodes. copper rod act as the anode. PVP act as a stabilizer. Silver Nano-particles were characterized by UV-Visible Spectroscopy, X-Ray Diffractometer (XRD), and Fourier transform infrared spectroscopy (FTIR). In this case absorption peak was produced at 230 nm. Silver oxide Nano-particles were produced as examined by an X-ray diffractometer. Elemental evaluation of silver Nano-particles has been examined by XRD, exposing the silver particles to the colloidal solution.                          

EXPERIMENTAL WORK

In this chapter, we will talk about the apparatus used in experiments and the characterization methods to study about different qualities of Nano-particles. By applying atmospheric pressure micro-plasma on electrolytic aqueous solution Nano-particles of different diameters were produced. To fabricate adequate size and stable Nano-particles, distinct amounts of metallic target and precursors were consumed. The Nano-particles produced were tested by various characterization methods.

Material used

To synthesize nanoparticles in an aqueous solution for this research work, various metallic precursors and surfactants had been used.

Silver Nitrate

In this research work, to synthesize silver Nano-particles we use silver nitrate as a precursor. Most of the time silver nitrate was extensively used for the development of silver Nano-particles. First, we dissolve silver nitrate in distilled water to make silver ions, as it is soluble in water, using micro-plasma silver ions produced, hence silver Nano-particles generate.

Stabilizer or Surfactant

To avoid agglomeration or aggregation and to regulate the production of Nano-particles, stabilizers play a crucial role at the production level. The main reasons for oxidation and agglomerations are high surface energy and thermodynamic instability of Nano-particles. At that time stabilizers act as obstacles and shield the surface of the Nano-particles, hence stabilizers play a vital role to control the extra development of Nano-particles. It also prevents needless reactions with other Nano-particles and chemicals and disturbs the optical properties of Nano-particles. Every surfactant has a specific dielectric constant, when we add a stabilizer or surfactant agent to Nano-particles, it will cause variations in the dielectric constant of Nano-particles, like at lower height it causes a change in peak absorbance wavelength, hence producing move in band edge. Nano-particles were easily dispersed in solution because by adding surfactant in colloidal solution, their surface tension decreased hence Nano-particles were easily scattered in solution. In this experiment, we applied polyvinyl pyrrolidine (PVP) and Sodium dodecyl sulfonate (SDS) as stabilizers or surfactants

Polyvinyl Pyrrolidone (PVP)

To grow newly Nano-particles Polyvinyl pyrrolidone plays a role in steric stabilization. In some other fields, Polyvinyl pyrrolidone was recognized as a binding agent. In colloidal solution, Nano-particles can be oxidized, destabilized, or agglomerated then PVP plays a role to control the agglomeration and coagulation of Nano-particles.

Sodium Dodecyl Sulfate (SDS)

 In some experiments, we use Sodium Dodecyl sulfate as a stabilizer, also known as an anionic stabilizer. By sticking on the surface of Nano-particles, SDS regulate their size of them. In an aqueous solution, SDS has low surface tension. In colloidal solution, SDS acts as a capping agent and controls the agglomeration of NPs. with Nano-particles SDS provides unproductive capping connections.

Distilled Water

To produce the electrolytic solution and an aqueous solution of metallic salts we add distilled water as a solvent.

 

Experimental Structure for the fabrication

The experiment consists of the following arrangements

• ·         DC power supply
• ·         Measuring system
• ·         Beakers
• ·         Micro-plasma Holder
• ·         Micro-plasma Capillary tube
• ·         Gas Flow meter
• ·       Magnetic Stirrer

Experimentation

For the preparation of silver Nano-composites, purchased PVP and AgNo₃ from sigma Aldrich. Prepare AgNo₃ aqueous solution (500ml) at different concentrations (0.5 mm, 1 mm, 2 mm, 4 Mm) with the proper amount of AgNo₃ .3Ho dissolved in distilled water. Same PVP was also prepared at different concentrations (0.5 mm, 1 mm, 2 Mm) by mixing in distilled water but PVP is 10% more as compared to AgNo₃. Both PVP and Silver Nitrate solution mixed together. 60% of silver Nitrate and 40% PVP were mixed together and continuously magnetically stirred before and during plasma processing_.

In this experiment, Nano-particles consist of polymer Nanocomposites produced only in a single step. Synthesis technique which depends on room temperature, direct current atmospheric pressure, and plasma-liquid interaction AgNP’s directly produced from AgNO₃ with PVP.

This setup consists of a Stainless-steel capillary tube having an outer diameter (of 1mm) and inner diameter (0.5 mm). Capillary tube act as Cathode. Argon gas cylinder attached to the capillary tube with gas flow meter. A carbon rod that is placed at a 1.6 cm distance from the capillary tube, acts as the anode. The carbon rod dip into the electrolyte solution but the capillary tube is at some distance from the surface of the solution. The solution consisted of PVP and AgNO₃ placed in a beaker. When we turn on the gas, the gas flow through the capillary tube. To produce micro-plasma a potential difference was also applied between anode and cathode, because this potential difference cause breakdown of Argon Gas, then high energy electron produces which will be helpful in the breakdown of AgNO₃. In this experiment, a maximum amount of 5 kv voltage and 4mA current were applied in parallel to the resistance between electrodes. When gas is provided and voltage is applied to gas, then Argon Gas breakdown leads to the production of micro-plasma, leading to the production of silver ions. The color of the solution changed within a few minutes which shows the generation of silver ions. Hence silver ions produced that further reduced and produce silver Nano-particles.

X-Ray Diffraction

To recognize the crystal lattice alignment and any unidentified material crystal assembly, a Non-Destructive technique is applied called X-Ray Diffraction. This technique also brings into play calculating the mean distance among layers of the atom, size of the grain, inner pressure, and to check the shape of tiny crystalline regions. To procurement of definitive quality diffraction data, united for effortlessness usage and elasticity to rapidly shift for various applications, X-Ray Diffractometer was fabricated. The principle of X-RD is that when an X-Ray falls and operates on a substance, a diffraction pattern is produced. It gives a graphical or pictorial representation to check the quality and performance of the material. The crystal atoms have three- a dimensional assembly of atoms. Atoms are organized at equal separation. In all crystal structure assembly, atomic layer distance is different. This distance differs from the distinctive alignment of crystallographic planes.

When a specific wavelength λ of X-Ray fall on the material surface with an angle θ, few waves are bent from the material’s upper layer and few waves will have bent from the second layer. Both X-Rays meet and interrelate constructively, hence bending occurs if they accomplish the state considering that

2d Sin θ = nλ

This is called Bragg’s Law In this equation “n” is the command of diffraction and “d” is the two layers’ distance. When we design angle and consequential diffraction peaks intensity, then a characteristic spectrum of the given material sample is attained.

Ultraviolet-Visible Spectroscopy

When a light beam passes over an experimental sample or it reflects from a sample surface, then the dimensions of lessening the light beam is called Ultra-Violet Visible Spectroscopy. In contrast to visible light, UV light has a smaller wavelength. When source material release an Ultra Violet-Visible light beam in spectrophotometry, then this light can be divided into two portions.

1)    Reference Beam 

2)    Sample Beam

Sample beam is a concentrating beam that releases from the pure cell by which the solution is examined.

The remaining half light beam is called a reference beam that emits from the same source but it does not consist of the solution the only solvent is being examined. To investigate the required wavelength zone, this UV -Visible Spectroscopy is devised that can prepare the contrast between two beams. This easy, high speed, and low cast technique used to find out the intensity of a chemical in solution. In this spectroscopy technique, a beam consists of 180 to 1100 nm wavelength forwarded to a cuvette across the solution.  Hence Ultra Violet or Visible radiations taken up by the material sample of the cuvette. Then a graph was designed among different wavelength scales and beam absorption by sample. To estimate band gap of material we use the formula,                        

(αhv)ⁿ =  A (hv - E_g )

 

For numerical testing, the spectroscopy technique operates by UV and Visible spectrum which tells about the compound quantity of sample.

We use spectroscopy for

·         Detection of functional groups

·         Detection of impurities

·         Qualitative analysis

·         Quantitative analysis

·         Single compound without chromophore Drugs

·         Drugs with chromophore reagent

·         It assists to demonstrate the connection among sets.

·         It is beneficial to identify bonds of compounds.

    Fourier Transform Infrared Spectrometer (FTIR)

    Most commonly FTIR (Fourier Transform Infrared Spectrometer) operated in polymeric science, pharmaceutical industry, synthesis of organic, analysis of food and petrochemical engineering. In the chemical reaction process and to find unbalanced materials FTIR spectrometer was used. FTIR spectrometer is also related to chromatography.

FTIR spectrometer related to infrared region whose range is 12800 ~ 10 cm^-1. This zone is divided into three regions near-infrared region (12800 ~ 4000 cm^-1), mid infrared region (4000 ~ 200 cm^-1) and far-infrared region (50 ~ 1000 cm^-1).

Results and Discussion 

To study the synthesized silver Nano-particles, various characterization techniques were used. This chapter concentrate on the results and assessment that was accomplished next to the characterization of prepared Nano-particles by the micro-plasma technique. UV-Visible spectroscopy is used to know about the formation and optical properties of metallic Nano-particles. The X-ray diffraction technique is used to examine the size and shape of Nano-particles.

UV-Visible Spectroscopy of AgNP’s with Silver Nitrate

Surface Plasmon Resonance is an important process in which photons link with oscillations of plasma that were produced by the conduction of electrons. SPR phenomenon occurs at the appearance of metallic Nano-particles and is used to create a combined oscillation having definite light frequency in the oscillating electromagnetic light field relating to positive metallic lattice.

The full width at half maximum and wavelength of SPR peak influence the average size, shape and size distribution of Nano-particles. The average size of Nano-particles has a direct relation with the FWHM of the resonant peak. The energy confinement of electrons, holes, excitations, phonons, and Plasmon’s occur in accordance of the shape of Nano-particles.  The color of silver Nano-particles solutions varies with respect to the size of the Nano-particles. Thus, in controlling the optical properties of Nano-particles, their shape and size act an important role.

SPR band for noble metal Nano-particles like AgNP’s, and AgNP’s occur in UV-Visible spectrum. The composition, shape, size, and dielectric environment of Nano-particles define the band position on the SPR peak. The Color of Nano-particles change as the concentration and size of Nano-particle vary during 5minute of plasma treatment at 2mA.

UV-Visible spectrum approved the production of Silver Nano-particles by micro-plasma. The absorption peaks were examined at 206 nm, 226 nm, and 230 nm corresponding to the growth of Silver Nano-particles in an electrolytic solution that was subjected to micro-plasma for 10 minutes. This result concludes that surfactant free silver Nano-particles produced at low initial AgNO₃ precursor concentration. A very short wavelength indicates that a large amount of silver Nano-particles produced that consist of small size, and therefore sharp FWHM. Absorption peak height linked with the concentration of Nano-particles produced in solution, more density of synthesized NPs, then the SPR peak will also be large as more absorption by silver ions take place and more silver Nano-particles produced.

UV-Visible Spectroscopy of AgNo₃ with PVP

UV-Visible absorption spectra of Silver Nano-particles produced in an aqueous solution of Silver nitrate and Polyvinylpyrrolidone by micro-plasma. Silver Nano-particles with PVP as polymer indicate the SPR spectra of silver NPs that was existing in colloidal solution. Maximum and only single sharp absorption peak produced at 230 nm. This result show that silver Nano-particles produced by silver nitrate with PVP have same size, shape. The sharpness of the peak indicates that it has short FWHM and thus a small size of Silver Nano-particles. This result also informs that to produce silver Nano-particles at high concentration of silver nitrate, PVP was added to prevent agglomeration.

 FTIR spectroscopy of AgNO₃  

The main objective to use PVP in this experiment is to control the growth and agglomeration by providing shielding layer on it. This experiment shows that the particles have a diameter of less than 50 nm. By adding PVP, it maintains size, and particles were spread in an improved way. Due to the introduction of PVP silver ions will react with N or O of PVP and will produce a protective layer at the particles surface. This layer will control the development and prevent particles from agglomeration. Zhang et al studied the possible reaction of PVP and how it shields particles having about 50 nm size. According to equation (1) and (2), he assumed that both reactions are equal. The FTIR spectrum of silver Nano-particles consisting of diameter less than 50nm. There were peaks obtained due to the resonance of carbon and oxygen C-O at 1643, peaks of C-N at 1019 and 1074, and N-OH peak at 1288. By matching the above spectrum with the PVP spectrum (fig) there were no variations occurred in the C-O peak that was at 1643 due to the addition of PVP.

But their variations occur in the C-N peak at 1019 and 1074 as it becomes strengthened due to PVP and moves at 1035 and 1074 and the peak of the N-OH complex becomes a weekend. The reason of the change of spectrum due to C-N bond showed that reaction between silver and N is important and the effect of silver and O was not important.

The main cause of PVP in silver Nano-particles for providing coverage was N of PVP that reacts with silver and produces a protection layer. As it is in the knowledge that in the reaction of N and Ag⁺ steric effect occurs but there are two reasons due to which steric effect decrease. First is that electronegativity of N was less than that of oxygen, that’s why the ability to denote electron was more in N as compared to O. so N react with silver ions more fatly. The second is that the steric effect has no more influence between silver and PVP when the particle size was less than 50 nm. so, the reaction of PVP and silver was basically on N but not on O.

FTIR spectroscopy of AgNO₃ with PVP

XRD spectrum of Silver Nano-particles

 UV-Vis Spectrum approve the development of silver NPs but the structural properties like size and shape were determined by X-Ray diffraction. For this intention, colloidal solution of silver Nano-particles was placed on a glass substrate and allowed to dry. These ready samples then allowed to examined by means of X-Ray Diffraction system. The result obtained by this characterization technique was noted, shown in the figure by origin software All typical spectrums of nanostructures were presented with some extra peaks at 450 which correspond to the small presence of Nickel content in obtained results. As all samples were fabricated at atmospheric conditions and were put on a glass substrate (amorphous) for characterization, some extra peaks were observed due to air contamination and Nickel anode reduction.

XRD result demonstrate a well-defined diffraction peak at 19⁰ and 29⁰ that point out the presence of silver oxide with lattice planes (020) and (11 -1) respectively indicating Monoclinic structure (JCPDS 00-040-1054). Because the sample was characterized after a long time of fabrication process, that’s why silver Nano-particles were oxidized during that duration that demonstrating the monoclinic structure of colloidal silver Nano-particle after the treatment by micro-plasma.

XRD spectrum of silver Nano-particles with PVP

X-Ray Diffraction result demonstrate two diffraction peaks at 19 and 29 same as above specify the presence of silver Nano-particles with lattice plane (020) and (11 -1) respectively confirmed by reference code (JCPDS 00-040-1054). Because the sample were characterized after long time of fabrication process, that’s why silver Nano-particles were oxidized during that duration that demonstrate the monoclinic structure of colloidal silver Nano-particle after the treatment by micro-plasma.

Conclusions

Metallic Nano-particles and Metallic Nano-composites have been made up at room temperature, atmospheric pressure using Micro-plasma like silver Nano-particles and silver Nano-composites were manufactured using micro-plasma. In this experiment, stainless steel capillary tube was used as the cathode, and a carbon rod was used as the anode. First of all, we prepare an electrolytic solution by dissolving silver Nitrate at some ratio, then it was immersed in distilled water. Micro-plasma was produced between stainless steel capillary and an electrolytic solution. Due to the redox reaction silver ions are produced then silver ions react with high-energy electrons of micro-plasma and silver Nano-particles generate.

In second method, we use a high amount of silver nitrate so we use Polyvinyl pyrrolidone to protect it from agglomeration and to control size of Nano-particles. Prepared solution of PVP and silver Nitrate in distilled water separately, then we add PVP solution in silver nitrate solution. When this solution was open to microplasma, then silver ions were reduced by high energetic electrons of microplasma and at the end produced silver Nano-particles. These Nano-particles were analyzed by UV-Vis Spectroscopy for the confirmation of Nano-particles and for elemental analysis XRD and FTIR were used. The results obtained by UV-Vis Spectroscopy, XRD and FTIR was well dispersed silver Nano-particles consisting of standard values. These Nano-particles are fully Bio-compatible as they are pure and clean. They can be applicable for antibacterial purpose, drug delivery, antiviral, anti-fungal, and treatment of cancer etc.

Nano-particles can be produced by using this method consisting of more controlled size and shape, that can be applied in various applications. Many other metallic salts can be used for the development of their Nano-particles. Other metallic Nano-composites will also be formed by this technique.