Optical Properties of Polyvinyl Alcohol Membrane with n-HAp for Bio-Medical Applications View PDF

Composite membrane as aflexible materials have found varied applications in industrial and biomedical simultaneously, the recent studies have shown essential improvement for membrane properties by inclusion of nanoparticles as afillers with high portion ratio in inorganic polymers [1]. The combination between two parts polymer and filler is as aresult of collection the advantage of two component systems parts together [2], for example flexibility, chemical stability, elasticity, in additionmechanical and thermal stabilities [3].

Poly(vinyl alcohol) PVA, is a water-soluble polymer, it has been selected as an organic part for bio composite. PVA membranes are flexible materials and own, high dimensional stability, high transparency and super permeability properties. PVA has been a known semi-crystalline polymer which possesses certain physical properties due to its crystal-amorphous interfacial effect [4].

An inorganic bioactive essential such as, nHApnano-particles have been purposely compound with hydrogels to offer essential biological and mechanical properties [5]. Hydroxyapatite, HAP or calcium phosphate (Ca₁₀(PO₄)₆ (OH)₂, has been regularly employed formerly as scaffold or implanting materials in biomedical applications, due to its unique biological action and physicochemical properties [6]. Furthermore, nHAp has superior specific surface area and excellent mechanical and biological properties [7]. Here, the purpose behind incorporation of HAp into PVA matrix allows reducing the glass transition temperature (Tg), the crystallinity degree, and thus increases the amorphous phase of the PVA polymer matrix.

Biomedical composite have been used in many applicationsincluding dental,bone and tissue implant, temporary skin cover or burn dressing, drug delivery materials, blend membrane,synthetic cartilage in recon structure joint surgery and artificial organs because it have good properties [8], it isgood biocompatibility,carcinogenicity, non-toxityand desirable physical properties such as rubbery and elastic nature, resistant to oil, high degree of swelling in aqueous solutions [9].

The study of this materials have been a key element of bone tissue engineeringThe present study is focused toinvestigation the effect of dopingdifferent concentrationof nHApon the optical propertiesof the PVAmatrix.

Synthesis of nHAP powder

nHAp powder was prepared by wet chemical precipitation process by weighing (19.718gm) of Ca(NO₃)₂.4H₂O and (6.603 gm) of (NH₄)₂HPO₄, then dissolving the materials in deionized water separately. The pH of each aqueous solution was adjusted to 11 by using NH₄OH solution. Dropwise addition of Ca(NO₃)₂.4H₂O aqueous solution to vigorously magnetic stirred (NH₄)₂HPO₄ solution is achieved at room temperature for about 1h.The resulted mixture is a milky in color and somewhat gelatinous precipitate ions were occurred at stirred for 1h. The precipitates were washed with distilled waterand then left immersed in distilled waterfor 24h for ageingthen filtered and dried at 100?over nightusing an oven and then crushed to very fine powder.

Preparation of PVA_ nHAPmembrane

Composite films were prepared in this study by using solution casting technique,PVA was dissolved in double distilled water by using magnetic stirrer then nHAp powder was added with ratio are (5,10,15, and20) wt% and mixed until get homogeneous solutions. Absorption and transmission spectra were record for wavelength 220-820 nm.

Scanning Electron Microscopy (SEM) Analysis

Size and morphology of nHAp were studied by Scanning electron microscope,the nanoparticles are spherical in shape,the structure of Nano particlesdistributed uniformly (Figure 1).

A (UV-210⁰A shimedza) double beam spectrophotometer with wavelength range (220-820) nm was used to measure the absorption spectra of the samples. The optical absorbance against the wavelength of the light incident for (PVA_nHAp) composites waspresented in thefigure (Figure 2).

As shown in figure the absorbance increases with increase of nHAP concentration and this attributed to high absorbance of nHAp (Figure 2). Absorbance spectrum shows increase in absorption at wavelength near to the absorption edge,the energy correspondingto this region determine the band gap of the composite sample [10], the increasing of nHAp concentrationincreased absorption edge in the range (220-820) nm of wavelength.

Transmittance spectra was presented in the figure, the optical transitions was increased with wavelength for all samples,the optical transmission for pure PVA was nearly 92% while it decreased to 50%with increasing nHAp concentration to 20%, and this attributed to increase of the absorbance (Figure 3).

Figure shows the variation of absorption coefficient for (PVA-nHAP) as a function of photon energy ,absorption coefficient can calculate from equation (Figure 4) [5].

α =2.303

Where A is absorbance and d is the thickness of sample,the values of (α) are less than (10⁴ cm^-1) (the fundamental of absorption coefficient can be used to determines the nature of the optical band gap E_g, A plot of (αhν )^1/2 versus photon energy as shown in figure 5, the energy band gap of the pure sample was 3.4evand decreasedafter increasing the concentration to 3.2ev, 1.2ev and 0.6ev for (5,10 and 15) wt%, respectively, and reach to 0.2ev for sample with 20 wt%.

Reflective index and extinction coefficient for (PVA-nHAp) films as a function of wavelength are shown in figures 6 and 7 respectively.

The reflective index for composite decreases with increasing of wavelength while,reflective index closely related to the electronicpolarization of ion and local field in side materials from the figure thereflective index increasing with increased of nHAP concentration which is a result of increasing the number of atomic refractions due to increase linear polarizability (Figure 6).

energy.

Figure 8 and figure 9 presentedthe variation of real and imaginary part of dielectric constants ?₁= n²-k₂ [11] and E₂=2nk[12], ?₁ mainly depends on n²  because of small values of k², ?₂ mainly depend on the (k) values, dielectric constants increases with increasing nHAp concentration andthe parameters are almost constant at higher wavelength.

Figure 10 shows the variation of optical conductivity of (PVA-nHAp) composite optical conductivity for all samples increases with increasing of nHAp concentration due to high absorbed of polymer composite films,the increase of optical conductivity and decrease in band gap energy with increase of nHAp concentration can be attributed in the increase in number of mobile charge carriers and also to the increase in amorphous nature of polymer composite.

This paper illustrate that the optical properties of  (PVA-nHAP) enhanced and improved by increasing the concentration of nHAP. The absorbance and optical conductivity wasincreased with increasing nHAP concentration while the transmittance and the reflective index decreased. The energy band gap of the pure sample was 3.4ev and decreasedwith increasing the concentration and reach to 0.2ev for 20wt%.

1. Madzokere TC, Karthigeyan A (2015) Electrospun silver/poly (vinyl alcohol) nanocompositemembrane: A model for the study, design and characterization of antibiofouling and high performance water purification membranes. Int J Chemtech Res 7: 1329-1343.
2. Shakir AA (2017) Vicker'shardness and compressive strength evaluation of a dental composite resin polymerized by conventional light and argon laser. Int J Chemtech Res 10: 617-623.
3. Mustafa FA (2013) Optical properties of NaI doped polyvinyl alcohol films.Phys Sci Res Int 1: 1-9.
4. Tawansi A, El-Khodary A, Abdelnaby MM (2005) Astudy of physical properties of Fecl3 filled PVA. Curr Appl Phys 5: 572-578.
5. Shakir AA,Kadim IH, Al-saad LF (2016) Optical properties of Polyvinyl alcohol-Diammoniumphosphate composite. Int J Chemtech Res 9: 470-475.
6. Thein-Han WW, Misra RD (2009) Biomimetic chitosan-nanohydroxyapatite composite scaffolds for bone tissue engineering.Acta Biomater 5: 1182-1197.
7. Peter M, Ganesh N, Selvamurugan N, Nair SV, Furuike T, et al. (2010) Preparation and characterization of chitosan-gelatin/nanohydroxyapatite composite scaffolds for tissue engineering applications. Carbohydr Polym 80: 687-694.
8. Tsioptsias C, Panayiotou C (2008) Preparation of cellulose-nanohydroxyapatite composite scaffolds from ionic liquid solutions. Carbohydr Polym 74: 99-105.
9. Teimouri A, Azadi M, Shams Ghahfarokhi Z, Razavizadeh R (2017) Preparation and characterization of novel β-chitin/nanodiopside/nanohydroxyapatite composite scaffolds for tissue engineering applications. J Biomater Sci Polym Ed 28: 1-14.
10. Das R, Pandey S (2011) Comparison of optical properties of bulk and nano crystalline thin films of CdS using different precursors. Int J Mater Sci 1: 35-40.
11. Ezema FI, Asogwa PU, Ekwealor AB, Ugwuoke PE, Osuji RU (2007) Growth and optical properties of Ag₂S thin films deposited by chemical bath deposition te technique. J Univ Chem Technol Met 42: 217-222.
12. Abdullah OG, Muhammad DS (2010) Physical properties of pure and copper oxide doped polystyrene films. IJoMS 5: 537-545.