INTRODUCTION:

Inorganic materials like metal oxides dispersed polymers constitute a new class of polymer nanocomposite materials, which shows various properties and applications. [1-2]. Composite materials exhibit markedly improved properties and applications compared to the pure polymers. Inorganic materials filled in polymer matrix are responsible for the integrity of these properties and applications [3-4]. Researchers are given more attraction for the conventionally filled polymers due its high thermal stability and heat resistant property. Several attempts are made to enhance the desired properties of polymers by preparing its nanocopmosites. Reinforcing utility at nano scale level drive improved properties for nanocomposites [5-6].

Polymeric materials with nanostructure can also be prepared by fine dispersion of inorganic nanomaterials of size typically 10-100nm dispersed in an organic polymer matrix. [7]. In same direction, nanocomposite materials based on nanosized inorganic materials have been of great interest to researchers due to their applications [8-9]. Fibrous materials like metals/ metal sulphides /metal oxides etc dispersed polymer nanocomposites have been extensively studied since they exhibit interesting properties with many applications such as quantum electronic devices, magnetic recording materials, sensors, capacitors, smart windows, toners in photocopying, conducting paints and rechargeable batteries [10-14].These composites are often prepared by dispersing nanomaterials in a non-conducting polymer matrix [15].

The present investigation reports the synthesis of lithium nickalate dispersed poly(methyl methacrylate) nanocomposite film (LiNiO₂-PMMA) through solvent casting method. The as prepared composite films were characterized by different characterization techniques.

MATERIALS AND METHODS:

Poly(methyl methacrylate) was obtained commercially. Acetone is used as a solvent for preparation of lithium nickalate dispersed PMMA composite film. Solvent casting method is adopted for the synthesis of composite film.

Synthesis of Pol(methyl methacrylate)-Lithium nickalate (LiNiO₂-PMMA) nanocomposite film.

Lithium nickalate dispersed PMMA nanocomposte film was prepared by solvent casting method. 2g of PMMA was stirred in 50ml of acetone and is kept for 10 hours in a closed container and the solution was stirred under magnetic stirrer for 10 minutes. 0.1g of as prepared lithium nickalate nanoparticles are mixed in to the PMMA gel thoroughly in a rotary evaporator which was constantly maintained at 80-90 ⁰C in a water bath. The gel solution containing Lithium nickalate was transferred into a petridish containing hot water as an immiscible solvent and it is kept 8 hours for evaporation of acetone. The fine lithium nickalate dispersed PMMA film was obtained and are characterized by various characterization techniques. The optical image of as prepared PMMA composite film is given in figure 1.

Figure1: Optical image of LiNiO₂-PMMA nanocomposite film

Instrumentation

The powder X-ray diffraction pattern of lithium nickalate dispersed poly(methyl methacrylate) nanocomposite film was obtained from GEOL JDX-8P X-ray diffractometer using CoKa radiation. The morphology of the nanocomposite film was obtained from Leica Cambridge-440 scanning electron microscope. The infrared spectrum of PMMA composite was recorded on a Perkin-Elmer FTIR spectrometer [model 100] in the range 4000-300cm^-1.

RESULTS AND DISCUSSION:

X-ray diffraction

XRD pattern of pure PMMA sample is reported in our earlier work [16]. The pattern shows the absence of Braggs reflections indicates the amorphous nature of PMMA. Figure 2 shows the indexed XRD pattern of lithium nickalate dispersed PMMA nanocomposite film. The pattern shows the presence of some lithium nickalate reflections and is indexed in the pattern by the reference of JCPDS file 09-063. The lithium nickalate peaks in the composite pattern confirm the formation of lithium nickalte dispersed PMMA composite and development of crystallinity in the polymer matrix. Development of crystallinity in PMMA matrix is due to the complexation of lithium nickalte nanomaterials with PMMA matrix. A comparison of the X-ray diffraction pattern of pure PMMAwith its lithium nickalate dispersed PMMA nanocomposites shows that the diffraction peaks is due to development of crystallinity in the amorphous PMMA. The broad halos in the region 5 to 20⁰ correspond to the organic phase present in the PMMA.

Figure2: XRD pattern of LiNiO₂-PMMA nanocomposite film

Scanning Electron Micrograph

Figure 3 shows SEM image of lithium nickalate dispersed PMMA nanocomposite film. Fine particles of lithium nickalate particles on the PMMA matrix can be observed. Irregular shaped lithium nickalate particles with self doped compact arrangement can also be seen. Close packed compact arrangemet of lithium nickalate particles with PMMA confirms the composite formation.

Figure 3: SEM image of LiNiO₂-PMMA composite film

Infrared spectroscopy

Figure 4 shows FTIR spectrum of LiNiO₂-PMMA composite film. FTIR of pure PMMA is discussed in our earlier study [16]. Some additional peaks and shift in the frequencies in the PMMA composite spectrum in comparison with that of pure PMMA is observed. Some peaks shifts in the composite spectrum are due to the presence of inserted lithium nickalatein the PMMA matrix and it may be possible due to H-type interactions between metal oxide and polymer matrix. Some characteristic peak of metal-oxygen [17]below 1000 cm^-1 is appeared in the composite spectrum indicates the presence of lithium nickalate particles. Some oxide peaks in the composite spectrum due to masked in the polymer matrix.

Figure 4: FTIR of LiNiO₂-PMMA composite film

CONCLUSIONS:

Development of crystallinity in amorphous Poly(methyl methacrylate) takes place due to incorporation of lithium nickalate. Morphological study represents the change in morphology with addition of nanoscopic inorganic materials to polymers. Additional reflections and shifted frequency in the FTIR study is observed in PMMA composite compared to its pure PMMA. The preparation of various PMMA nanocomposite films with different fibrous materials is our future direction of work.

ACKNOWLEDGEMENT:

Authors are grateful to Prof. A Venkataraman, Department of Chemistry, Gulbarga University, kalaburagi for useful discussion in spectral analysis. Thanks are due to President and Principal, BKIT, Bhalki for constant support and encouragement.

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Received on 01.02.2017 Modified on 10.02.2017

Asian J. Research Chem. 2017; 10(2):142-144.

DOI: 10.5958/0974-4150.2017.00023.2