Sage Journals: Discover world-class research

Abstract

In the present study, solution casting method was used for the preparation of nanocomposite films. Primarily, the surface of copper (II) oxide (CuO) nanoparticles was modified with biosafe molecules such as citric acid and ascorbic acid for better dispersion in the polymer matrix. Then novel nanocomposite films were fabricated by loading various percentages of modified CuO nanoparticles in the poly(vinyl chloride) matrix. The ultraviolet (UV)-blocking effects of nanocomposites and their optical properties were studied using UV-visible spectroscopy. Also, other analyses, including Fourier transform infrared spectroscopy, mechanical tensile test, thermogravimetric analysis, and X-microscopy, were performed for investigating thermal, mechanical, and morphological properties of the hybrid materials.

Keywords

Poly(vinyl chloride)CuO nanoparticles nanocomposite films surface modification biosafe molecules

Introduction

In nanotechnology, particle is defined as a small object that behaves as a whole unit with respect to its transport and properties. The particles with an average size of 1–100 nm are called nanoparticles (NPs).^1,2

Copper (II) oxide (CuO) as a kind of NP has the monoclinic crystal system that can be shaped in different forms, such as nanowires and nanorods.³ The main advantage that makes the CuO NPs unique for electronic and photonic applications such as one-dimensional p-type semiconductor and optical equipment polisher is its narrow bandgap (1.2 eV).⁴ In addition, it is used as heterogeneous catalysts, gas sensors, optical switch, magnetic storage media, field-emission devices, solar cells, and rectifiers as well as in different acoustic applications.^5

–12 In recent years, different attempts were made to enhance the physical characteristics and photocatalytic activity of nanocomposites (NCs) by loading CuO NPs to various polymeric matrixes.^13

–17

Pure poly(vinyl chloride) (PVC) is a white and brittle solid polymer. The main two advantages of this polymer are its relatively low cost, biological, and chemical resistance.¹⁸ On the other hand, PVC is a thermoplastic polymer and its properties are usually categorized based on the rigidity and flexibility. The rigid form of PVC is used for some applications such as doors, windows, bottles, other nonfood packaging, and cards (such as bank cards). PVC can be softer and more flexible by adding the plasticizers.¹⁹ The flexible PVC can be used as an alternative for rubbers, electrical cable insulations, artificial leathers, and inflatable products.^20,21

Ascorbic acid (AA) is a white solid powder with the γ-lactone structure. The l-enantiomer of AA is called vitamin C, which is hydrosoluble and has antioxidant properties. Vitamin C can be found in fresh fruits and vegetables due to the glucose reaction process.^22,23

Citric acid (CA) with the C₆H₈O₇ formula is a weak organic acid, which is produced naturally in citrus fruits as a preservative.²⁴ It is an inexpensive and nontoxic acid that can be used as a flavoring agent, a chelating agent, an emulsifier, a pH adjusting agent, and in pharmaceuticals. As a special application, CA can enhance the performance of starch, polyvinyl alcohol/starch, cellulose, and thermoplastic starch/polylactic acid blend by acting as a cross-linking agent.^25,26

In the present study, CuO NPs were modified with biosafe molecules including CA and AA, and their effects on NCs films were studied. Polymer-based NCs and modified CuO were fabricated under ultrasonic irradiation. The properties of the prepared samples were characterized by different techniques such as Fourier transform infrared (FTIR) spectroscopy, ultraviolet–visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and mechanical tensile test. Dispersion of NPs in PVC matrix was studied using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM).

Experimental

Materials

CuO nanopowder was obtained from Neutrino Co. (Tehran, Iran), with average particle size <50 nm and specific surface area >80 m² g⁻¹. CA and AA were supplied from Merck Chemical Co. and used as received. PVC was a commercial polymer produced by LG Chem (Korea Origin), with weight-average molecular weight = 78,000 g mol⁻¹. Tetrahydrofuran (THF) was purchased from JEONG Wang, Siheung, South Korea.

Characterization

FTIR spectra on a Jasco-680 (Tokyo, Japan) spectrophotometer in the range of 400–4000 cm⁻¹ were characterized to identify the chemical bonds of the prepared samples in potassium bromide pellets for powder materials, and spectrograms of NC films were acquired directly. Preparation of NCs was accomplished using MISONIX (Raleigh, North Carolina, USA) ultrasonic liquid processors, XL-2000 SERIES (USA), with frequency wave 2.25 × 10⁴ Hz and power of 100 W. TGA data were taken on STA503 instrument (TA Instruments, New Castle, Delaware, USA) at a heating rate of 20°C min⁻¹ from 25°C to 800°C under argon atmosphere. XRD spectra were collected on a Philips X’pert MPD diffractometer (Netherlands) with a copper (Cu) K _α (λ = 1.540 Å), a tube voltage of 40 kV, and tube current of 35 mA in the range of 5°–100° of 2θ. The microstructure of the fabricated samples was obtained using FESEM analysis (Hitachi S-4160, Japan), and TEM images were acquired using a Philips CM 120 microscope. UV-Vis spectra were obtained using a UV/Vis/near IR spectrophotometer, JASCO, V-570, in the wavelength scan range from 200 nm to 800 nm. Tensile testing was operated at room temperature on a testometric tniversal testing machine M350/500 (UK). Tests were carried out with a crosshead speed of 5 mm min⁻¹ until/to a deformation of 20% and then at a speed of 50 mm min⁻¹ at break. The dimensions of the test specimens were 35 × 9 × 0.05 mm³.

Surface modification of CuO NPs with CA and AA

For the surface treatment of CuO NPs, 0.01 g of CA was dissolved in 7 mL of deionized (DI) water and sonicated for 30 min (solution 1). Also 0.01 g of AA were dissolved in 7 mL of DI water and sonicated for 30 min (solution 2). Then, 0.10 g of CuO NPs were dispersed in 7 mL of DI water and the obtained mixture was ultrasonicated for 30 min (solution 3). In the next step, solutions 1 and 2 were mixed and irradiated under sonication for 30 min. At last, solution 3 was added to the previous mixture and irradiated under ultrasonic for 30 min. Ultimately, this solution was dried at room temperature for 24 h to give the CuO-CA-AA (modified CuO) NPs.

Preparation of the NC films

In this procedure, 0.10 g of PVC was dissolved in 5 mL of THF. Then various amounts of the modified CuO NPs (4, 8, and 12 wt%) were added to PVC solutions. The PVC/modified CuO suspensions were ultrasonicated for 1 h and then stirred for 14 h at room temperature. Once again the suspensions were sonicated for 1 h, and the obtained suspensions were casted onto uncovered glass petri dishes for 1 day in order to evaporate the THF solvent. After removal of THF, films were fabricated and could be easily separated from the glass petri dishes.

Results and discussion

Preparation of the NC film

Recently, NPs have received a great attention due to the enhancement of NC properties.^27
–29 Good dispersion of NPs in the polymer matrix plays an important role in the development of NC properties. On the other hand, surface modification of NPs can improve the dispersion process. According to the recent articles, molecules such as dicarboxylic acid, chiral diacid, and CA have been used in order to modify the surfaces of NPs.^30
–32 In this study, biosafe molecules including CA and AA were used for double-layer surface modification. Coating of the modification layers (CA and AA) on the CuO NPs substrate is due to the possible interactions between the functional groups presented on the NPs surface, especially hydroxyl groups and the modifiers. The effect of various amounts of prepared NPs on PVC in THF was investigated. The schematic of the process is shown in Figures 1 and 2.

Figure 1.

Surface modification of CuO NPs with CA and AA under ultrasonic irradiation. CuO: copper (II) oxide; NPs: nanoparticles; CA: citric acid; AA: ascorbic acid.

Figure 2.

The schematic image of the formation of PVC/modified CuO NC. PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

FTIR spectroscopy

The FTIR spectrum of pure CuO is shown in Figure 3(a). The characteristic peak around about 475 cm⁻¹ refers to Cu–O bond stretching. The appearance of a broad absorption band at 3298 cm⁻¹ confirms the presence of stretching mode of water molecules and/or surface hydroxyls.³³ Also, the absorption bands at 1600–1700 cm⁻¹ can be related to the bending vibrations of O–H. Pure CA has strong intermolecular and intramolecular H bonding that create expansive peaks in the region of 2500–3500 cm⁻¹ (Figure 3(b)). In addition, the peaks around 1700 and 1755 cm⁻¹ corresponds with CA carbonyl vibration peaks.³⁴ For pure AA (Figure 3(c)), the peak at 1672 cm⁻¹ attributes to the vibration of C=O and also the broad band peak in 2500–3000 cm⁻¹ ascribes the hydroxyl groups of pure AA.³⁵ Figure 3(d) represents the spectrum of modified CuO with CA and AA. The peak at 1621 cm⁻¹ is owing to the carbonyl groups of modifiers. Besides, broad band peak in area of 2800–4000 cm⁻¹ is observed which confirms different hydroxyl groups of CA and AA. Figure 4 illustrates the FTIR spectra of pure PVC and its NCs. For pure PVC, peaks under 3000 cm⁻¹ characterize the C–H stretching mode. In addition, peaks at 1430, 1252, 616, and 692 cm⁻¹ are related to CH₂, CH₂–Cl, C–Cl, respectively.^36,37 The presence of modified CuO in the polymer matrix creates changes in FTIR spectrum of pure PVC which is observable in the region of 430–540 cm⁻¹. Also the peak around 1560 cm⁻¹ shows a rise in intensity with increasing the percentage of modified filler.

Figure 3.

FTIR spectra of (a) pure CuO NPs, (b) CA, (c) AA, and (d) modified CuO NPs. FTIR: Fourier transform infrared; CuO: copper (II) oxide; NPs: nanoparticles; CA: citric acid; AA: ascorbic acid.

Figure 4.

FTIR patterns of (a) pure PVC, (b) PVC/modified CuO NC 4 wt%, (c) PVC/modified CuO NC 8 wt%, and (d) PVC/modified CuO NC 12 wt%. FTIR: Fourier transform infrared; PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

X-Ray diffraction

The XRD patterns of CuO NPs, CA, AA, and modified CuO NPs are shown in Figure 5. The diffraction peaks in Figure 5(a) can be corresponded to the monoclinic structure of single-phase CuO.³⁸ Due to the usage of slight amount of CA and AA, diffraction peaks did not appear in the curve of modified CuO NPs. The neat and modified CuO NPs almost show similar XRD patterns, indicating that crystalline structure of CuO NPs has no changes after surface modification with CA and AA.

Figure 5.

XRD spectra of (a) pure CuO NPs, (b) CA, (c) AA, and (d) modified CuO NPs. XRD: X-ray diffraction; CuO: copper (II) oxide; NPs: nanoparticles; CA: citric acid; AA: ascorbic acid.

The XRD results of the PVC, PVC/modified CuO NC 4, 8, and 12 wt% are demonstrated in Figure 6. The diffraction pattern of PVC illustrates that this polymer is amorphous. According to the XRD patterns of the NCs, intensity of peaks rises with increasing the amount of CuO NPs in PVC matrix.

Figure 6.

XRD curves of (a) modified CuO NPs, (b) pure PVC, (c) PVC/modified CuO NC 4 wt%, (d) PVC/modified CuO NC 8 wt%, and (e) PVC/modified CuO NC 12 wt%. XRD: X-ray diffraction; CuO: copper (II) oxide; NPs: nanoparticles; PVC: poly(vinyl chloride); NC: nanocomposite.

Microscopy characterization

FESEM and TEM techniques were used to investigate the morphology and distribution of modified CuO NPs in PVC matrix. Figure 7 displays the FESEM photographs of modified CuO and NCs with different magnification. These images indicate that modified CuO NPs are well dispersed in the polymer matrix, and the aggregation is reduced. FESEM image of NC 12 wt% shows little agglomeration. The homogeneous dispersion of CuO NPs might be due to the presence of capping agents on their surfaces, and ultrasonic irradiation technique leads to a decrease in surface energy of NPs.

Figure 7.

FESEM micrographs of (a) modified CuO NPs, (b) pure PVC, (c) PVC/modified CuO NC 4 wt%, (d) PVC/modified CuO NC 8 wt%, and (e) PVC/modified CuO NC 12 wt%. FESEM: field-emission scanning electron microscopic; CuO: copper (II) oxide; NPs: nanoparticles; PVC: poly(vinyl chloride); NC: nanocomposite.

TEM micrographs of pure CuO NPs, modified CuO, and PVC/modified CuO NCs 8 wt% are demonstrated in Figure 8. The spherical shape and nanoscale-modified CuO are seen in these pictures, and the average particle size is 10.80 ± 2.91 nm. It was expected that the particles to be quantum dots, but after performing the fluorescence test, a sufficient result did not achieve. TEM observations confirm the modification surface of CuO NPs, since the average particle size is reduced from 30 nm (for pure CuO) to around 10 nm (for modified CuO). The size distribution histograms for pure CuO NPs, modified CuO, and PVC/modified CuO NCs 8 wt% showed mean particle sizes of 29.12, 10.80, and 5.87 nm, respectively (Figure 9).

Figure 8.

TEM micrographs of pure (a) CuO NPs, (b, c) modified CuO NPs, and (d, e) PVC/modified CuO NC 8 wt% at different magnifications and their histograms. TEM: transmission electron microscopic; CuO: copper (II) oxide; NPs: nanoparticles; PVC: poly(vinyl chloride); NC: nanocomposite.

Figure 9.

The size distribution histograms for (a) pure CuO NPs, (b) modified CuO NPs, and (c) PVC/modified CuO NC 8 wt%. CuO: copper (II) oxide; NPs: nanoparticles; PVC: poly(vinyl chloride); NC: nanocomposite.

Thermal properties

Thermal properties of modified CuO, pure PVC, and the prepared films were measured by TGA under argon atmosphere at a heating rate of 20°C min⁻¹. Before TGA, the NC films were dried at 70°C to remove the solvent. The thermograms of neat and modified CuO are exhibited in Figure 10. In decomposition processes, the physisorbed water molecules eliminate around 120°C. According to the TGA curve of modified CuO, degradation process around 200°C can be corresponded to the decomposition of both modifiers, because the thermal degradation of AA and CA are in the temperature range of 190°C and 197°C, respectively.³⁹ From this graph, it is found that about 12% of CA and AA are grafted, which confirm the presence of capping agents on the surface of CuO NPs.

Figure 10.

TGA thermograms of pure CuO and modified CuO NPs. TGA: thermogravimetric analysis; CuO: copper (II) oxide; NPs: nanoparticles.

The weight loss of 5 wt% (T ₅) and 10 wt% (T ₁₀) and char yield at 800°C of NC films are summarized in Table 1. Also, their thermograms are demonstrated in Figure 11. This figure characterizes two distinct steps for thermal decomposition processes. The weight loss step around 100°C is ascribed to dehydration. The weight loss in the region 220–350°C is related to dehydrochlorination (loss of HCl) and the weight loss in the region 440–570°C can be corresponding to chain degradation of the polymer and its NCs.³⁷ The curves of the 4 and 8 wt% NC films and 12 wt% film are situated at higher and lower temperatures than pure PVC, respectively. This occurrence may be attributable to the catalytic effect of CuO NPs.²⁷ Hence, it can be concluded that catalytic properties of CuO NPs and as a result, the easier thermal decomposition of polymer appears by adding larger amounts of 8 wt%.

Table 1.

Thermal properties of the PVC and PVC/modified CuO NCs.

Sample	T ₅ (°C)^a	T ₁₀ (°C)^b	Char yield (%)^c
Pure PVC	240.34	252.48	23.33
NC 4 wt%	265.33	272.03	30.28
NC 8 wt%	260.79	269.08	31.08
NC 12 wt%	102.85	218.35	22.62

PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite; T ₅: temperature at 5% weight loss; T ₁₀: temperature at 10% weight loss; TGA: thermogravimetric analysis.

^a T ₅ was recorded using TGA at a heating rate of 20°C min⁻¹ under argon atmosphere.

^b T ₁₀ was recorded by TGA at heating rate of 20°C min⁻¹ under argon atmosphere.

^cWeight percentage of material left undecomposed after TGA at a temperature of 800°C under argon atmosphere.

Figure 11.

TGA thermograms of (a) neat PVC, (b) PVC/modified CuO NC 4 wt%, (c) PVC/modified CuO NC 8 wt%, and (d) PVC/modified CuO NC 12 wt%. TGA: thermogravimetric analysis; PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

The char yield of pure PVC is 23.33%, and the residual weight of the NCs for different weight fractions of modified CuO NPs: 4, 8, and 12 wt% are 30.28%, 31.08%, and 22.62%, respectively.

Optical properties of NCs

UV-Vis spectroscopy was applied to investigate the optical properties of NC films. The UV-Vis absorption spectra of PVC and PVC/modified CuO NCs (4, 8, and 12 wt%) are illustrated in Figure 12. The intensity of peaks increases by adding rising percentages of modified CuO in NCs. In figure 12, d–d transitions are observed due to Cu²⁺ has d orbital with 9 valance electrons. The d–d transition wavelengths are often placed below 400 nm, but because the particles are in nanosize, these transitions shift to lower wavelengths.⁴⁰ The peak in region near 277 nm may be related to n → π* transitions of PVC . Also, the unsaturated bonds of the modifiers show the maximum peak at l = 209 nm.⁴¹ Hence, the absorbance of NC films enhances in comparison with neat polymer, the obtained NCs can be useful to shield the UV–C radiation (280–10 nm; Figure 13).⁴²

Figure 12.

UV-Vis spectra of (a) neat PVC, (b) PVC/modified CuO NC 4 wt%, (c) PVC/modified CuO NC 8 wt%, and (d) PVC/modified CuO NC 12 wt%. UV-Vis: ultraviolet–visible; PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

Figure 13.

Photographs of (a) pure PVC, (b) PVC/modified CuO NC 4 wt%, (c) PVC/modified CuO NC 8 wt%, and (d) PVC/modified CuO NC 12 wt%. PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

Mechanical properties

To investigate the tensile properties of pure PVC and NC films, mechanical tests were operated. Stress versus strain curves of hybrid specimens are depicted in Figure 14. According to Figure 14 and Table 2, some mechanical behavior of NC films such as elongation and strain are enhanced in comparison with neat polymer, but stress is decreased with increasing the content of modified CuO NPs. The most important reason can be the reduction of polymer matrix uniformity by loading filler through it. These data show that flexibility of the NCs is improved in comparison with the pure PVC.⁴³

Figure 14.

Stress–strain curves of (a) pure PVC, (b) PVC/modified CuO NC 4 wt%, (c) PVC/modified CuO NC 8 wt%, and (d) PVC/modified CuO NC 12 wt%. PVC: poly(vinyl chloride); CuO: copper (II) oxide; NC: nanocomposite.

Table 2.

Summary of mechanical data for the PVC and its composites.

Sample	Stress (MPa)	Strain (%)	Elastic modulus (MPa)	Elongation (mm)
Pure PVC	41.33	2.65	2061.91	0.93
NC 4 wt%	37.81	5.19	702.38	1.04
NC 8 wt%	37.13	5.36	763.05	1.07
NC 12 wt%	32.27	5.65	899.99	1.13
Pure PVC	41.33	2.65	2061.91	0.93

PVC: poly(vinyl chloride); NC: nanocomposite.

Conclusions

PVC is one of the most extensively used forms of plastics. So it is necessary to improve its properties. In this work, before the preparation of PVC NCs, the surface of CuO NPs was grafted with CA and AA as capping agents. Then, various amounts of modified CuO NPs loaded to PVC matrix and the PVC/modified CuO NCs were successfully fabricated under ultrasonic irradiation as a green and an easy method. The properties of these polymeric NCs were investigated by different techniques. The presence of PVC and CuO NPs were confirmed using characterized absorption bands in the NCs FTIR spectrograms. Based on FESEM and TEM results, the average particles size reduced after surface modification, and CuO NPs were uniformly dispersed into PVC backbone. TGA exhibited that thermal resistance of NCs decreased by loading greater than 8 wt%. The optical properties of NC films represented an absorption in the region of UV–C. Also, according to the results of the mechanical tests, the flexibility of the NCs improved with the incorporation of modified CuO NPs in the PVC matrix.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Authors deliver their gratitude to the Research Affairs Division Isfahan University of Technology (IUT), Isfahan and the National Elite Foundation (NEF) for financial support. Further financial support from Iran Nanotechnology Initiative Council (INIC) and Center of Excellency in Sensors and Green Chemistry Research (IUT) is gratefully acknowledged.

References

Chellaram

Murugaboopathi

John

. Significance of nanotechnology in food industry. APCBEE Proc 2014; 8: 109–113.

Paul

Robeson

. Polymer nanotechnology: nanocomposites. Polymer 2008; 49: 3187–3204.

Xiao

H-M

Zhu

L-P

Liu

X-M

. Anomalous ferromagnetic behavior of CuO nanorods synthesized via hydrothermal method. Solid State Commun 2007; 141: 431–435.

Suleiman

Mousa

Hussein

. Copper (II)-oxide nanostructures: synthesis, characterizations and their applications—review. J. Mater Environ Sci 2013; 4: 792–797.

Rahimnejad

Setayesh

Gholami

. A credible role of copper oxide on structure of nanocrystalline mesoporous titanium dioxide. J Iran Chem Soc 2008; 5: 367–374.

Chowdhuri

Gupta

Sreenivas

. Response speed of SnO₂-based H₂S gas sensors with CuO nanoparticles. Appl Phys Lett 2004; 84: 1180–1182.

Patil

. CuO-modified tin titanate thick film resistors as H₂-gas sensors. Sens Actuators, B 2007; 123: 233–239.

Teng

Yao

Zheng

. Synthesis of flower-like CuO nanostructures as a sensitive sensor for catalysis. Sens Actuators B 2008; 134: 761–768.

Xiang

Huang

. A comparison of anodically grown CuO nanotube film and Cu₂O film as anodes for lithium ion batteries. J Solid State Electrochem 2008; 12: 941–945.

10.

Wang

Pan

Zhao

. Fabrication of CuO film with network-like architectures through solution-immersion and their application in lithium ion batteries. J Power Sources 2007; 167: 206–211.

11.

Vaseem

Umar

Hahn

. Flower-shaped CuO nanostructures: structural, photocatalytic and XANES studies. Catal Commun 2008; 10: 11–16.

12.

Deka

Kong

Seo

. Controlled growth of CuO nanowires on woven carbon fibers and effects on the mechanical properties of woven carbon fiber/polyester composites. Compos A 2015; 69: 56–63.

13.

Battez

González

Viesca

. CuO, ZrO₂ and ZnO nanoparticles as antiwear additive in oil lubricants. Wear 2008; 265: 422–428.

14.

Cho

Bahadur

. Study of the tribological synergistic effects in nano CuO-filled and fiber-reinforced polyphenylene sulfide composites. Wear 2005; 258: 835–845.

15.

Miwa

Kaneco

Katsumata

. Photocatalytic hydrogen production from aqueous methanol solution with CuO/Al₂O₃/TiO₂ nanocomposite. Int J Hydrogen Energy 2010; 35: 6554–6560.

16.

Wang

. Facile synthesis and photocatalytic activity of ZnO–CuO nanocomposite. Superlattices Microstruct 2010; 47: 615–623.

17.

Liu

Z-L

Deng

J-C

Deng

J-J

. Fabrication and photocatalysis of CuO/ZnO nano-composites via a new method. Mater Sci Eng, B 2008; 150: 99–104.

18.

Liu

. Nano-TiO₂@ Ag/PVC film with enhanced antibacterial activities and photocatalytic properties. Appl Surf Sci 2012; 258: 4667–4671.

19.

Coltro

Pitta

Madaleno

. Performance evaluation of new plasticizers for stretch PVC films. Poly Test 2013; 32: 272–278.

20.

Asadinezhad

Novák

Lehocký

. An in vitro bacterial adhesion assessment of surface-modified medical-grade PVC. Colloids Surf, B 2010; 77: 246–256.

21.

Yang

Deng

Peng

. Enhanced solid-phase photocatalytic degradation activity of a poly (vinyl chloride)-TiO₂ nanocomposite film with bismuth oxyiodide. Chem Eng Technol 2011; 34: 886–892.

22.

Pisoschi

Pop

Serban

. Electrochemical methods for ascorbic acid determination. Electrochim Acta 2014; 121: 443–460.

23.

Gabriel

Cayabyab

JEC

Tan

AKL

. Development and validation of a predictive model for the influences of selected product and process variables on ascorbic acid degradation in simulated fruit juice. Food Chem 2015; 177: 295–303.

24.

Oliveira

MLN

Malagoni

Franco

. Solubility of citric acid in water, ethanol, n-propanol and in mixtures of ethanol + water. Fluid Phase Equilib 2013; 352: 110–113.

25.

Ning

Xingxiang

. Effects of water on the properties of thermoplastic starch poly (lactic acid) blend containing citric acid. J Thermoplast Compos 2010; 23: 19–34.

26.

Wang

Ren

. Properties of polyvinyl alcohol/xylan composite films with citric acid. Carbohydr Polym 2014; 103: 94–99.

27.

Guo

Liang

Pereira

. CuO nanoparticle filled vinyl-ester resin nanocomposites: fabrication, characterization and property analysis. Compos Sci Technol 2007; 67: 2036–2044.

28.

Gandhi

Subramani

RHH

Ramakrishnan

. Ultrasound assisted one pot synthesis of nano-sized CuO and its nanocomposite with poly (vinyl alcohol). J Mater Sci 2010; 45: 1688–1694.

29.

Moreira

Sphaier

Reis

. Experimental investigation of heat conduction in polyester–Al₂O₃ and polyester–CuO nanocomposites. Exp Therm Fluid Sci 2011; 35: 1458–1462.

30.

Mallakpour

Vahabi

. Application of chiral diacid N-trimellitylimido-l-valine for the surface modification of copper oxide as inorganic filler and preparation of poly (amide–imide)/cupric oxide nanocomposites. J Thermoplast Compos 2016; 29: 234–248.

31.

Mallakpour

Dinari

Azadi

. Grafting of citric acid as a green coupling agent on the surface of cuo nanoparticle and its application for synthesis and characterization of novel nanocomposites based on poly (amide-imide) containing N-trimellitylimido-l-valine linkage. Poly Plas Technol Eng 2015; 54: 594–602.

32.

Mallakpour

Ayatollahi

. Development of novel chiral poly (amide–imide)/bionanocomposites containing N,N′-(pyromellitoyl)-bis-phenylalanine units reinforced by organoclay and modified TiO₂ . J Thermoplast Compos 2015; 28: 3–18.

33.

Yang

Xiao

Wang

. Synthesis and microwave modification of CuO nanoparticles: crystallinity and morphological variations, catalysis, and gas sensing. J Colloid Interface Sci 2014; 435: 34–42.

34.

Goodarzi

Sahoo

Swihart

. Aqueous ferrofluid of citric acid coated magnetite particles. Mat Res Soc Synp Proc 2004; 789: N6.6.1–N6.6.6.

35.

Jafarpour

Rezaeifard

Ghahramaninezhad

. Dioxomolybdenum (VI) complex immobilized on ascorbic acid coated TiO₂ nanoparticles catalyzed heterogeneous oxidation of olefins and sulfides. Green Chem 2015; 17: 442–452.

36.

Dunbai

Changgen

Demin

. Preparation and mechanical properties of solid-phase grafting nanocomposites of PVC/graft copolymers/MMT. J Wuhan Univ Technol 2006; 21: 5–8.

37.

Elashmawi

Hakeem

Marei

. Structure and performance of ZnO/PVC nanocomposites. Physica B 2010; 405: 4163–4169.

38.

Sahooli

Sabbaghi

Saboori

. Synthesis and characterization of mono sized CuO nanoparticles. Mater Let 2012; 81: 169–172.

39.

Halpern

Urbanski

Weinstock

. A biodegradable thermoset polymer made by esterification of citric acid and glycerol. J Biomed MaterRes 2014; 102: 1467–1477.

40.

Sarwar

Zulfiqar

Ahmad

. Polyamide–silica nanocomposites: mechanical, morphological and thermomechanical investigations. Poly Int 2008; 57: 292–296.

41.

Yang

Gong

Peng

. High photocatalytic degradation activity of the polyvinyl chloride (PVC)–vitamin C (VC)–TiO₂ nano-composite film. J Hazard Mater 2010; 178: 152–156.

42.

Mallakpour

Aalizadeh

. Application of TiO₂ nanoparticles modified with bioactive diacid in manufacturing of polymer nanocomposites containing 4,4′-sulfonyl dianiline and N,N′-(pyromellitoyl)-bis-l-valine diacid. Synth React Met-Org Chem 2014; 44: 1450–1456.

43.

Mallakpour

Behranvand

. Optical, mechanical, and thermal behavior of poly (vinyl alcohol) composite films embedded with biosafe and optically active poly (amide–imide)-ZnO quantum dot nanocomposite as a novel reinforcement. Colloid Polym Sci 2014; 292: 2857–2867.

Surface treatment of copper (II) oxide nanoparticles using citric acid and ascorbic acid as biocompatible molecules and their utilization for the preparation of poly(vinyl chloride) novel nanocomposite films

Abstract

Keywords

Introduction

Experimental

Materials

Characterization

Surface modification of CuO NPs with CA and AA

Preparation of the NC films

Results and discussion

Preparation of the NC film

FTIR spectroscopy

X-Ray diffraction

Microscopy characterization

Thermal properties

Optical properties of NCs

Mechanical properties

Conclusions

Footnotes

Declaration of Conflicting Interests

Funding

References