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methyl methacrylate copolymer
Materials Chemistry and Physics 178 (2016) 12e20
Contents lists available at ScienceDirect
Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys
Radiation synthesis and characterization of zinc phthalocyanine composite based on 2-hydroxyethyl methacrylate/methyl methacrylate copolymer A.M. Abdel Ghaffar a, *, Tamer E. Youssef b, c, Hanan H. Mohamed d a
Radiation Research of Polymer Chemistry Department, Industrial Irradiation Division, National Center for Radiation Research and Technology, Atomic Energy Authority P.O. Box 29, Nasr City, Cairo, Egypt Applied Organic Chemistry Department, Chemical Industries Research Division, National Research Center, Dokki, Cairo, 12622, Egypt c Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, 21589, Saudi Arabia d Chemistry Department, Faculty of Science, Helwan University, Ain Helwan, Cairo, Egypt b
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
The preparation of Poly(HEMA/MMA/ ZnPc) by radiation forming modified composites. The low concentration of ZcPc (1 or 1.5 wt %) lead to form outstanding properties. These composites are a potential candidate for wide range of applications.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 July 2015 Received in revised form 13 March 2016 Accepted 1 April 2016 Available online 28 April 2016
The synthesis and characterization of new 2-hydroxyethyl methacrylate-co-methyl methacrylate/zinc phthalocyanine composite Poly(HEMA/MMA/ZnPc) is described for the first time in this study. The aim of this research is to present possibility of radiation synthesis of the newly zinc phthalocyanine composites as potential candidates for wide range of applications. Gel (%) and swelling for Poly(hydroxyethyl methacrylate) Poly(HEMA) and the based Poly(hydroxyethyl methacrylate/methyl methacrylate) copolymer Poly(HEMA/MMA) with different composition 100/0, 95/5, 90/10 and 80/20 wt % were evaluated. It was found that Poly(HEMA/MMA) copolymer with composition 95/5 wt % characterized by its high swelling property at pH 7.4. The prepared composites I and II Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively have been characterized by FTIR and TGA. The effect of gamma irradiation on the chemical properties of composite I was described. It is observed that the Zinc phthalocyanine with low concentration 1 wt % enhance chemical, thermal properties and stabilization against gamma radiation of the prepared composite I. © 2016 Elsevier B.V. All rights reserved.
Keywords: Irradiation effects Composite materials Thermal properties Chemical analysis
1. Introduction
* Corresponding author. E-mail address: [email protected] (A.M. Abdel Ghaffar). http://dx.doi.org/10.1016/j.matchemphys.2016.04.012 0254-0584/© 2016 Elsevier B.V. All rights reserved.
Poly(2-hydroxyethylmethacrylate) Poly(HEMA) hydrogels have been widely described in literature as materials for biomedical
A.M. Abdel Ghaffar et al. / Materials Chemistry and Physics 178 (2016) 12e20
applications. This is due to their high biocompatibility. However, a swollen Poly(HEMA) hydrogel has poor mechanical properties, lead to limited applications, such as for soft contact lenses or drug release carriers [1,2]. In addition, Poly(methyl methacrylate) Poly(MMA) is characterized by its highly transparent and high refractive index polymer [3,4]. Therefore copolymerization of Hydroxyethyl methacrylate with Methyl methacrylate result in forming copolymer has good physical, chemical and mechanical properties [5e7]. Previous reports showed that using of metallophthalocyanine to incorporate into several kinds of polymers forming polymer composites. These composites have widely utilized in the different fields of life, such as biomedical applications and materials sciences [8e11]. For example, attaching of sulfo-substituted cobalt(II) phthalocyanines to Poly(methyl methacrylate) or polypropylene matrix have been described previously [12]. A successfully polymerization via the incorporation of silicon(IV) phthalocyanine dichloride (SiPcCl2) to the thermo-responsive PEG-methacrylates based polymers has been described for photodynamic therapy (PDT) application [13]. Wang et al. prepared a water-soluble Zinc phthalocyanine functionalized with 2-methylacrylic acid 6-(3,4-dicyano-phenoxy)-hexyl ester (MADCE). The resulted polymer composite has good singlet oxygen quantum yields for providing polymeric materials for photodynamic therapy applications [14]. The contribution of our group to this field of research has been quite remarkable and described in details in literature [15,16]. Therefore, incorporating of 2-Hydroxyethyl methacrylate/ Methyl methacrylate copolymer Poly(HEMA/MMA) with zinc phthalocyanines compounds may be a most useful combination for wide range of applications such as non-linear optics, chemical sensors, semiconductors, liquid crystals, medical application, electrochromic devices, Langmuire Blodgett films, photochromic materials, and as photosensitizers for photodynamic therapy [17,18].
2.2.3. Preparation of 2,3,9,10,16,17,23,24octahydroxyzincphthalocyanines [(OH)8ZnPc] The 2,3,9,10,16,17,23,24-octamethylzincphthalocyanine (1) was suspended in dichloromethane (100 mL) and BBr3 (24 mL, 254 mmol) was added under N2. The mixture was stirred for 3 days at room temperature, then methanol was added slowly and dark green suspension was formed. The suspended solution was centrifuged. The precipitated solids was filtered off, washed with methanol and dried under vacuum, to yield 85% of ZnPc 2, as black green powder. FTIR (KBr, cm1): 3313 (br-OH), 2956, 2920, 2855, 1654, 1544 (s),1468 (s), 1440 (m), 1322 (m), 1272 (m), 1140 (s), 1130, 920 (s), 880 (m), 753 (m). UVeVis (DMF), lmax (nm) 688, 622, 354. MS (FD): m/z 705.91 (Mþ).
2.2.4. Preparation of Poly(HEMA/MMA/ZnPc) composites To prepare composites I and II, Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively, methanol (85%) used as a solvent. Before irradiation the mixture were stirred in magnetic stirring for 20 min. The mixtures were transferred to glass ampoules, sealed and subject to gamma radiation at dose 35 kGy, and dose rate 0.65 Gy/sec as shown in Scheme 1 [8,20].
2. Experimental 2.1. Materials Reagent grade hydroxyethyl methacrylate of purity 97.8% (Merck, Germany), methyl methacrylate of purity 99.9% (Merck, Germany), and other all reagent grade chemicals were used as received. The starting precursor 2,3,9,10,16,17,23,24octamethylzincphthalocyanine (1) required for the synthesis of 2,3,9,10,16,17,23,24-octahydroxyzincphthalocyanine (2) was synthesized as reported in our previous work [19]. 2.2. Preparation 2.2.1. Gamma irradiation Radiation preparation of different copolymers and composites I and II Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively in this study were preformed at a dose rate ranged from 0.79 to 0.65 Gy/sec in air using the 60Co gamma cell facility of the National Center for Radiation Research and Technology, Cairo, Egypt. 2.2.2. Preparation of the Poly(HEMA/MMA) copolymers The mixtures of 2-hydroxyethyl methacrylate and methyl methacrylate with different composition 100/0, 95/5, 90/10 and 80/ 20 wt % were prepared using methanol (80%) as a solvent. The prepared comonomer mixture was transferred to glass ampoules, sealed and subject to direct irradiation at dose 30 kGy, and dose rate 0.79 Gy/sec at ambient temperature.
13
Scheme 1. Preparation of Poly(HEMA/MMA/ZnPc) composites.
14
2.3.
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2.10. Thermal analysis
H- NMR
1 H-NMR with referenced internally to residual solvent (CDCl3) were measured by using a BVT 3000 Bruker Spectro spin instrument operating at 300.13 MHz, product of Bruker, Germany.
2.4. UltravioleteVisible spectroscopy The (UVeVis) spectrum of ZnPc was taken in N,N-dimethylformamide (DMF) using a Shimadzu UV-1800 spectrophotometer, product of Shimadzu, Japan. 2.5. FD mass spectrum measurement FD mass spectrum measurement was carried out with a Varian MAT 711 a spectrometer, product of Agilent, Germany and reported as mass/charge (m/z). 2.6. Elementary analysis Elementary analysis was performed on a Carlo Erba Elemental Analyzer 1104, 1106, product of Thermo Scientific, Germany. 2.7. Gelation (%) To calculate the gelation percent, the prepared cylinder-shaped Poly(HEMA) and Poly(HEMA/MMA) copolymers were cut into small discs and dried in a vacuum oven at 45 C to constant weight. The Poly(HEMA) and Poly(HEMA/MMA) copolymers discs were soaked in distilled water to extract unreacted monomer and soluble parts at 70 C for 6 h in then dried at a vacuum oven to constant weight (Wg). The gelation (%) was calculated by the following equation:
Gelation ð%Þ ¼
Wg 100 Wo
(1)
where Wo is the weight of dried copolymer after irradiation, and Wg is the dried weight of the sample after extraction of soluble and unreacted species. 2.8. Swelling behavior
Shimadzu TGA system of type TGA-50 Thermogravimetric analyzer was used with nitrogen flow rate of 30 mL/min and heating rate was 20 C/min, from the ambient temperature up to 600 C. The TGA analysis were performed in Micro analytical center, Cairo University, Egypt.
3. Results and discussion The radiation-induced synthesis, of Poly(HEMA), Poly(HEMA/ MMA) copolymer and Poly(HEMA/MMA/ZnPc) composite I, II were reported in this study. It is found that radiation technology is an easy process control, possibility of for copolymer formation in one step. There is no waste and relatively low running costs etc. The route of synthesis Poly(HEMA), Poly(HEMA/MMA) copolymer and Poly(HEMA/MMA/ZnPc) composite I, II showed in Scheme 1 [8,20]. The samples were examined visually for homogeneity and transparency. It is found that the different copolymers at comonomer composition Poly(HEMA/MMA) (100/0): (95/5) (90/10) and (80/20) at comonomer concentration 40% and 50% give high homogeneity and transparency than that of comonomer concentration 30%.
3.1. Gelation (%) Gamma radiation polymerization of HEMA and copolymerization of HEMA with MMA at different composition in methanol [21,22] at dose 30 kGy, leads to the formation of insoluble polymeric network. The gelation (%) results are presented in Fig. 1. From Fig. 1 it is noted that there is a typically dependence of gelation (%) on the copolymer compositions. It was found that, the gelation (%) of Poly(HEMA) is slightly lower than that of Poly(HEMA/MMA) copolymers in all compositions. This is may be attributed to the higher degree of crosslinking density of Poly(HEMA/MMA) copolymers network by the effect of irradiation and also due to the crosslinking of hydrogen bonding formation inside the Poly(HEMA/MMA) copolymers matrix [23].
The prepared Poly(HEMA), Poly(HEMA/MMA) copolymer and composites I and II discs were soaked in bidistilled water of pHs values 2, 5, and 7.4 at room temperature. The pH of these solutions was adjusted by adding HCl or NaOH. Swollen samples were removed and dried superficially with filter paper. The swelling measurements continued until a constant weight was obtained for each sample. After the soaking procedure, the swelling (%) was calculated by Equation (2):
Water Uptake ð%Þ ¼
Ws Wo 100 Wo
(2)
where Wo and Ws are the weights of dry and swelled hydrogels, respectively. 2.9. Fourier Transform Infrared (FTIR) The functional groups of both copolymer and composites (I and II) were studied by using FTIR-4100 spectrophotometer product of Jasco, Japan. The spectra were recorded from 4000 to 400 cm1. The FTIR analysis were performed in Micro analytical center, Cairo University, Egypt.
Fig. 1. Gel (%) of Poly(HEMA) and Poly(HEMA/MMA) at different comonomer composition and at comonomer concentration 40%.
Fig. 2. Effect of time on the swelling (%) of different hydrogels at comonomer concentration (a) 30%, (b) 40%, (c) 50% and (d) effect of MMA content at 50% comonomer concentration.
Fig. 3. Effect of pH on the swelling (%) of (a) Poly(HEMA), (b) Poly (HEMA/MMA) (95/5 wt %) at different pH 2,5,7.4 (c) composites I and II at pH 7.4.
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3.2. Swelling behavior The swelling properties of the prepared Poly(HEMA), and Poly(HEMA/MMA) copolymer were studied in deionized water at room temperature. The plot of swelling (%) versus time is shown in Fig. 2. The effect of time taken to obtain optimum swelling for the prepared Poly(HEMA), and Poly(HEMA/MMA) copolymer. The optimum swelling is considered as the equilibrium swelling as no further increase in swelling is observed [24]. From Fig. (2aec) as comonomer concentration increased the swelling (%) decreased due to more crosslinked Poly(HEMA/MMA) structure formed. Also from Fig. (2aec) it is found that the swelling (%) of Poly(HEMA) is slightly higher than that of Poly(HEMA/MMA) copolymer with all different composition and concentration this is due to the hydrophilic hydroxyl groups (-OH) of HEMA which are free to form H-bonding resulting slightly higher water uptake (%) Also the lower swelling (%) of the Poly(HEMA/MMA) copolymer than Poly(HEMA) due to hydrophobic character of MMA where as concentration of MMA increased swelling (%) decreased as shown in Fig. 2d. 3.3. Effect of pH on swelling behavior The effect of pH on the swelling properties of Poly(HEMA), Poly(HEMA/MMA) copolymer with composition (95/5) and composites I and II were studied and shown in Fig. 3. From Fig. 3(a, b) it was found that as pH of the medium increased the swelling % increased up to pH 7.4 this is due to formation of ionizable hydroxyl and acrylate groups in Poly(HEMA) and Poly(HEMA/MMA) copolymer. Also the swelling behavior of Poly(HEMA/MMA) is higher than that of Poly(HEMA) this is may be due to formation of more ionizable acrylate groups in Poly(HEMA/ MMA) than only acrylate groups in Poly(HEMA). In case of composites I and II, it is found that as ZnPc added to (HEMA/MMA) the swelling behavior at pH 7.4 decreased this is due to hydrophobic nature of ZnPc which containing bulky aromatic group that increased hydrophobicity due to the steric hindrance of ZnPc added to composite I therefore swelling % slightly decreased. 3.4. Fourier Transform Infrared (FTIR) 3.4.1. Fourier Transform Infrared (FTIR) of the Poly(HEMA) and Poly(HEMA-co-MMA) The FTIR of the prepared Poly(HEMA) and Poly(HEMA/MMA) copolymer with different comonomer composition were shown in Fig. 4(aed) which give information about the copolymer composition. For both Poly(HEMA) and Poly(HEMA/MMA) copolymer the characteristic peaks are similar. The absorption peaks for hydroxyl and ester carbonyl groups appeared around 3340 cm1 and 1728 cm1, the peak appeared at 2952 cm1 is corresponding to stretching of normal alkane (CH), (CH2) and (CH3). The peak at 1456 cm1 corresponds to bending of normal alkane. In case of Poly(HEMA/MMA) copolymer the peak at 1397 cm1assigned to CH3 bending. It was found that as MMA content increase the intensity of (CH), (CH2), CH3 and (C]O) peaks increased which confirm the successful copolymerization of the two monomers to form Poly(HEMA/MMA) copolymer. 3.4.2. Fourier Transform Infrared (FTIR) of composite I and II. The structure of the newly composites I and II were characterized with FTIR. Similar bands of composites I and II in Fig. (5aec) to those obtained in case of Fig. 4(aed) with addition to the bands
Fig. 4. FTIR analysis of (a) Poly(HEMA), (b) Poly(HEMA/MMA) (95/5 wt %) (c) Poly(HEMA/MMA) (90/10 wt %) and (d) Poly(HEMA/MMA) (80/20 wt %).
appearing around 1272 and 1023 cm 1 which were assigned to CeN stretching. The intensity of the previous absorption bands increases with the increasing zinc phthalocyanine. 3.5. Effect of irradiation In order to study the effect of radiation [15,16] on the prepared Poly(HEMA/MMA/ZnPc) composite I. The prepared composite I was subject to irradiation at different doses 0, 10, 30, 40 kGy. The FTIR spectra of original composite I and irradiated composite I with different doses 0, 10, 30, 40 kGy are shown in Fig. (6aed). It is clear that minor differences in FTIR spectra were observed after irradiation with different doses. Therefore the addition of zinc phthalocyanine in the repeating units of the composites I act as stabilizing agent against gamma irradiation because of delocalization of excitation energy in the
A.M. Abdel Ghaffar et al. / Materials Chemistry and Physics 178 (2016) 12e20
17
Fig. 5. FTIR analysis of (a) Poly(HEMA/MMA) (95/5 wt %) (b) Composite I and (d) Composite II.
double and aromatic units [15,16]. Also due to large ionic radius of Zn in composites I. 3.6. Thermal analysis The thermal properties of the prepared Poly(HEMA) and Poly(HEMA/MMA) copolymer with different comonomer composition as well as their derivatives composites I and II were studied by thermogravimetric analysis (TGA) and shown in Figs. 7 and 8. Fig. 7(aed) for Poly(HEMA) and other prepared Poly(HEMA/ MMA) copolymer showed two stages of thermal decomposition. The first stage found to be around in the range of 40e125 C which corresponds to elimination of adsorbed moisture. The second step in the range of 170e440 C which correspond to major weight loss due to extensive degradation of the polymer backbone chain with maximum decomposition temperature (Tmax) 257 C for Poly(HEMA). The maximum decomposition temperature (Tmax) increased to 254, 258 and 288 C for Poly (HEMA/MMA) (95/5 wt %), (90/10 wt %) and 80/20 wt % respectively where as MMA content increased the Tmax increased. The maximum decomposition temperature (Tmax) followed by leaving a residue. The residue from the thermal decomposition of Poly(HEMA) and other prepared Poly(HEMA/MMA) copolymer left behind the maximum thermal decomposition temperature (T max), observed that, it increase with increasing MMA content due to the
Fig. 6. FTIR analysis of composite I irradiated with dose (a) 0 kGy (b) 10 kGy (b) 30 kGy and (d) 40 kGy composite I.
increase in crosslinking density. Therefore the observed maximum thermal decomposition temperature (Tmax) for the prepared copolymers refers to increase of thermal stability upon increasing MMA content. In case of composites I and II, it is clear that there are two stages of thermal decomposition Fig. 8 (aec). The first stage in the range 40e100 C, which is due to the loss of moisture followed by the second stage in the range 165e420 C which attributed to degradation of the copolymer backbone with maximum decomposition temperature (Tmax) of 254, 261.5 and 275 C for Poly (HEMA/MMA) (95/5 wt %), composites I and II respectively. It was found that the thermal stability increased with increasing the zinc phthalocyanine content.
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A.M. Abdel Ghaffar et al. / Materials Chemistry and Physics 178 (2016) 12e20
Fig. 7. TGA curves of (a) Poly(HEMA), (b) Poly(HEMA/MMA) (95/5 wt %) (c) Poly(HEMA/MMA) (90/10 wt %) and (d) Poly(HEMA/MMA) (80/20 wt %).
A.M. Abdel Ghaffar et al. / Materials Chemistry and Physics 178 (2016) 12e20
19
Fig. 8. TGA curves of (a) Poly(HEMA/MMA) (95/5 wt %) (b) Composite I and (d) Composite II.
4. Conclusion A highly specific, selective and easy process control was found with the use of radiation-induced synthesis for the 2hydroxyethyl methacrylate-co-methyl methacrylate/zinc phthalocyanine Poly(HEMA/MMA/ZnPc) composites I and II was described. The prepared Poly(HEMA/MMA) and composite I and II by gamma radiation characterized by good physical, chemical, and thermal properties. Considering these promising results for easily preparation of composites I and II make the irradiation as a method of choice in the preparation of copolymers for specific practical applications such as in biomedical field and materials science [7e10]. The effect of the zinc phthalocyanine on the chemical, thermal properties and stabilization against gamma radiation of the prepared composites was discussed. It was found that curing of Poly(HEMA/MMA) by addition of low concentration of ZnPc (1 and 1.5 wt %) lead to form outstanding properties such as high thermal
and chemical stability Also it act as stabilizing agent against gamma irradiation because of delocalization of excitation energy in the double and aromatic units [15,16].
References [1] C. Migliaresi, L. Nicodemo, L. Nicolais, P. Passerini, Polymer 25 (1984) 686e689. [2] Q. Tang, J.R. Yu, L. Chen, J. Zhu, Z.M. Hu, Curr. Appl. Phys. 10 (2010) 766e770. [3] C. Migliaresi, L. Nicodemo, L. Nicolais, P. Passerini, M. Stol, J. Hrouz, P. Cefelin, J. Biomed. Mater. Res. 18 (1984) 137e146. [4] L.B. Peppas, N.A. Peppas, Biomaterials 11 (1990) 635e644. [5] S.M. Reda, Sol. Energy 81 (2007) 755e760. [6] L. Zhang, D. Wu, Y. Chen, X. Wang, G. Zhao, H. Wan, C. Huang, Appl. Surf. Sci. 255 (2009) 6840e6845. [7] P.D. Dalton, L. Flynn, M.S. Shoichet, Biomaterials 23 (2002) 3843e3851. [8] M.N. Abbas, A.L.,A. Radwan, P. Bühlmann, M.A. Abd El Ghaffar, Am. J. Anal. Chem. 2 (2011) 820e831. [9] M.A. Abd El-Ghaffar, N.R. El-Halawany, H.A. Essawy, J. Appl. Polym. Sci. 108 (2008) 3225e3232.
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[10] M. Arvand, A. Pourhabib, R. Shemshadi, M. Giahi, Anal. Bioanal. Chem. 387 (2007) 1033e1039. [11] W. Chen, B. Zhao, Y. Pan, Y. Yao, S. Lu, S. Chen, L. Du, J. Colloid Interface Sci. 300 (2006) 626e632. [12] A. Voronina, N. Litova, I. Kuzmin, M. Razumov, M. Shepelev, S. Pukhovskaya, Eur. Chem. Bull. 3 (2014) 857e859. [13] J. Li, W. Zhang, Z. Hu, X.J. Jiang, T. Ngai, P.C. Lo, W.Z.G. Chen, Polym. Chem. 4 (2013) 782. [14] L. Wang, J. Li, W. Zhang, G. Chen, W. Zhang, X. Zhu, Polym. Chem. 5 (2014) 2872. [15] A.M. Abdel Ghaffar, T.E. Youssef, Polym. Compos. 28 (2007) 631e636. [16] T.E. Youssef, A.M. Abdel Ghaffar, J. Appl. Polym. Sci. 119 (2011) 134e141.
€ [17] S. Agırtas¸M, B. Cabir, S. Ozdemir, Dyes Pigments 96 (2013) 152e157. [18] G.K. Karaoglan, G. Gümrükçü, A. Koca, A. Gül, Dyes Pigments 88 (2011) 247e256. [19] T.E. Youssef, Polyhedron 29 (2010) 1776e1783. [20] M.R. Islam, L.G. Bach, J.M. Park, S.S. Hong, K.T. Lim, J. Appl. Polym. Sci. 127 (2013) 1569e1577. [21] J.S. Koo, P.G.R. Smith, R.B. Williams, M.C. Grossel, M.J. Whitcombe, Chem. Mater. 14 (2002) 5030e5036. n, J. Macromol. Sci. Part A Pure Appl. Chem. 51 [22] A. Szanka, G. Szarka, B. Iva (2014) 125e133. [23] M. Eid, J. Radiat. Res. Appl. Sci. 5 (2012) 455e476. [24] R. Katiyar, D.S. Bag, I. Nigam, Adv. Mater. Lett. 5 (2014) 214e222.
Contents lists available at ScienceDirect
Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys
Radiation synthesis and characterization of zinc phthalocyanine composite based on 2-hydroxyethyl methacrylate/methyl methacrylate copolymer A.M. Abdel Ghaffar a, *, Tamer E. Youssef b, c, Hanan H. Mohamed d a
Radiation Research of Polymer Chemistry Department, Industrial Irradiation Division, National Center for Radiation Research and Technology, Atomic Energy Authority P.O. Box 29, Nasr City, Cairo, Egypt Applied Organic Chemistry Department, Chemical Industries Research Division, National Research Center, Dokki, Cairo, 12622, Egypt c Chemical and Materials Engineering Department, Faculty of Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah, 21589, Saudi Arabia d Chemistry Department, Faculty of Science, Helwan University, Ain Helwan, Cairo, Egypt b
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
The preparation of Poly(HEMA/MMA/ ZnPc) by radiation forming modified composites. The low concentration of ZcPc (1 or 1.5 wt %) lead to form outstanding properties. These composites are a potential candidate for wide range of applications.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 9 July 2015 Received in revised form 13 March 2016 Accepted 1 April 2016 Available online 28 April 2016
The synthesis and characterization of new 2-hydroxyethyl methacrylate-co-methyl methacrylate/zinc phthalocyanine composite Poly(HEMA/MMA/ZnPc) is described for the first time in this study. The aim of this research is to present possibility of radiation synthesis of the newly zinc phthalocyanine composites as potential candidates for wide range of applications. Gel (%) and swelling for Poly(hydroxyethyl methacrylate) Poly(HEMA) and the based Poly(hydroxyethyl methacrylate/methyl methacrylate) copolymer Poly(HEMA/MMA) with different composition 100/0, 95/5, 90/10 and 80/20 wt % were evaluated. It was found that Poly(HEMA/MMA) copolymer with composition 95/5 wt % characterized by its high swelling property at pH 7.4. The prepared composites I and II Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively have been characterized by FTIR and TGA. The effect of gamma irradiation on the chemical properties of composite I was described. It is observed that the Zinc phthalocyanine with low concentration 1 wt % enhance chemical, thermal properties and stabilization against gamma radiation of the prepared composite I. © 2016 Elsevier B.V. All rights reserved.
Keywords: Irradiation effects Composite materials Thermal properties Chemical analysis
1. Introduction
* Corresponding author. E-mail address: [email protected] (A.M. Abdel Ghaffar). http://dx.doi.org/10.1016/j.matchemphys.2016.04.012 0254-0584/© 2016 Elsevier B.V. All rights reserved.
Poly(2-hydroxyethylmethacrylate) Poly(HEMA) hydrogels have been widely described in literature as materials for biomedical
A.M. Abdel Ghaffar et al. / Materials Chemistry and Physics 178 (2016) 12e20
applications. This is due to their high biocompatibility. However, a swollen Poly(HEMA) hydrogel has poor mechanical properties, lead to limited applications, such as for soft contact lenses or drug release carriers [1,2]. In addition, Poly(methyl methacrylate) Poly(MMA) is characterized by its highly transparent and high refractive index polymer [3,4]. Therefore copolymerization of Hydroxyethyl methacrylate with Methyl methacrylate result in forming copolymer has good physical, chemical and mechanical properties [5e7]. Previous reports showed that using of metallophthalocyanine to incorporate into several kinds of polymers forming polymer composites. These composites have widely utilized in the different fields of life, such as biomedical applications and materials sciences [8e11]. For example, attaching of sulfo-substituted cobalt(II) phthalocyanines to Poly(methyl methacrylate) or polypropylene matrix have been described previously [12]. A successfully polymerization via the incorporation of silicon(IV) phthalocyanine dichloride (SiPcCl2) to the thermo-responsive PEG-methacrylates based polymers has been described for photodynamic therapy (PDT) application [13]. Wang et al. prepared a water-soluble Zinc phthalocyanine functionalized with 2-methylacrylic acid 6-(3,4-dicyano-phenoxy)-hexyl ester (MADCE). The resulted polymer composite has good singlet oxygen quantum yields for providing polymeric materials for photodynamic therapy applications [14]. The contribution of our group to this field of research has been quite remarkable and described in details in literature [15,16]. Therefore, incorporating of 2-Hydroxyethyl methacrylate/ Methyl methacrylate copolymer Poly(HEMA/MMA) with zinc phthalocyanines compounds may be a most useful combination for wide range of applications such as non-linear optics, chemical sensors, semiconductors, liquid crystals, medical application, electrochromic devices, Langmuire Blodgett films, photochromic materials, and as photosensitizers for photodynamic therapy [17,18].
2.2.3. Preparation of 2,3,9,10,16,17,23,24octahydroxyzincphthalocyanines [(OH)8ZnPc] The 2,3,9,10,16,17,23,24-octamethylzincphthalocyanine (1) was suspended in dichloromethane (100 mL) and BBr3 (24 mL, 254 mmol) was added under N2. The mixture was stirred for 3 days at room temperature, then methanol was added slowly and dark green suspension was formed. The suspended solution was centrifuged. The precipitated solids was filtered off, washed with methanol and dried under vacuum, to yield 85% of ZnPc 2, as black green powder. FTIR (KBr, cm1): 3313 (br-OH), 2956, 2920, 2855, 1654, 1544 (s),1468 (s), 1440 (m), 1322 (m), 1272 (m), 1140 (s), 1130, 920 (s), 880 (m), 753 (m). UVeVis (DMF), lmax (nm) 688, 622, 354. MS (FD): m/z 705.91 (Mþ).
2.2.4. Preparation of Poly(HEMA/MMA/ZnPc) composites To prepare composites I and II, Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively, methanol (85%) used as a solvent. Before irradiation the mixture were stirred in magnetic stirring for 20 min. The mixtures were transferred to glass ampoules, sealed and subject to gamma radiation at dose 35 kGy, and dose rate 0.65 Gy/sec as shown in Scheme 1 [8,20].
2. Experimental 2.1. Materials Reagent grade hydroxyethyl methacrylate of purity 97.8% (Merck, Germany), methyl methacrylate of purity 99.9% (Merck, Germany), and other all reagent grade chemicals were used as received. The starting precursor 2,3,9,10,16,17,23,24octamethylzincphthalocyanine (1) required for the synthesis of 2,3,9,10,16,17,23,24-octahydroxyzincphthalocyanine (2) was synthesized as reported in our previous work [19]. 2.2. Preparation 2.2.1. Gamma irradiation Radiation preparation of different copolymers and composites I and II Poly(HEMA/MMA/ZnPc) with composition (95/5/1 wt%) and (95/5/1.5 wt%) respectively in this study were preformed at a dose rate ranged from 0.79 to 0.65 Gy/sec in air using the 60Co gamma cell facility of the National Center for Radiation Research and Technology, Cairo, Egypt. 2.2.2. Preparation of the Poly(HEMA/MMA) copolymers The mixtures of 2-hydroxyethyl methacrylate and methyl methacrylate with different composition 100/0, 95/5, 90/10 and 80/ 20 wt % were prepared using methanol (80%) as a solvent. The prepared comonomer mixture was transferred to glass ampoules, sealed and subject to direct irradiation at dose 30 kGy, and dose rate 0.79 Gy/sec at ambient temperature.
13
Scheme 1. Preparation of Poly(HEMA/MMA/ZnPc) composites.
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2.3.
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2.10. Thermal analysis
H- NMR
1 H-NMR with referenced internally to residual solvent (CDCl3) were measured by using a BVT 3000 Bruker Spectro spin instrument operating at 300.13 MHz, product of Bruker, Germany.
2.4. UltravioleteVisible spectroscopy The (UVeVis) spectrum of ZnPc was taken in N,N-dimethylformamide (DMF) using a Shimadzu UV-1800 spectrophotometer, product of Shimadzu, Japan. 2.5. FD mass spectrum measurement FD mass spectrum measurement was carried out with a Varian MAT 711 a spectrometer, product of Agilent, Germany and reported as mass/charge (m/z). 2.6. Elementary analysis Elementary analysis was performed on a Carlo Erba Elemental Analyzer 1104, 1106, product of Thermo Scientific, Germany. 2.7. Gelation (%) To calculate the gelation percent, the prepared cylinder-shaped Poly(HEMA) and Poly(HEMA/MMA) copolymers were cut into small discs and dried in a vacuum oven at 45 C to constant weight. The Poly(HEMA) and Poly(HEMA/MMA) copolymers discs were soaked in distilled water to extract unreacted monomer and soluble parts at 70 C for 6 h in then dried at a vacuum oven to constant weight (Wg). The gelation (%) was calculated by the following equation:
Gelation ð%Þ ¼
Wg 100 Wo
(1)
where Wo is the weight of dried copolymer after irradiation, and Wg is the dried weight of the sample after extraction of soluble and unreacted species. 2.8. Swelling behavior
Shimadzu TGA system of type TGA-50 Thermogravimetric analyzer was used with nitrogen flow rate of 30 mL/min and heating rate was 20 C/min, from the ambient temperature up to 600 C. The TGA analysis were performed in Micro analytical center, Cairo University, Egypt.
3. Results and discussion The radiation-induced synthesis, of Poly(HEMA), Poly(HEMA/ MMA) copolymer and Poly(HEMA/MMA/ZnPc) composite I, II were reported in this study. It is found that radiation technology is an easy process control, possibility of for copolymer formation in one step. There is no waste and relatively low running costs etc. The route of synthesis Poly(HEMA), Poly(HEMA/MMA) copolymer and Poly(HEMA/MMA/ZnPc) composite I, II showed in Scheme 1 [8,20]. The samples were examined visually for homogeneity and transparency. It is found that the different copolymers at comonomer composition Poly(HEMA/MMA) (100/0): (95/5) (90/10) and (80/20) at comonomer concentration 40% and 50% give high homogeneity and transparency than that of comonomer concentration 30%.
3.1. Gelation (%) Gamma radiation polymerization of HEMA and copolymerization of HEMA with MMA at different composition in methanol [21,22] at dose 30 kGy, leads to the formation of insoluble polymeric network. The gelation (%) results are presented in Fig. 1. From Fig. 1 it is noted that there is a typically dependence of gelation (%) on the copolymer compositions. It was found that, the gelation (%) of Poly(HEMA) is slightly lower than that of Poly(HEMA/MMA) copolymers in all compositions. This is may be attributed to the higher degree of crosslinking density of Poly(HEMA/MMA) copolymers network by the effect of irradiation and also due to the crosslinking of hydrogen bonding formation inside the Poly(HEMA/MMA) copolymers matrix [23].
The prepared Poly(HEMA), Poly(HEMA/MMA) copolymer and composites I and II discs were soaked in bidistilled water of pHs values 2, 5, and 7.4 at room temperature. The pH of these solutions was adjusted by adding HCl or NaOH. Swollen samples were removed and dried superficially with filter paper. The swelling measurements continued until a constant weight was obtained for each sample. After the soaking procedure, the swelling (%) was calculated by Equation (2):
Water Uptake ð%Þ ¼
Ws Wo 100 Wo
(2)
where Wo and Ws are the weights of dry and swelled hydrogels, respectively. 2.9. Fourier Transform Infrared (FTIR) The functional groups of both copolymer and composites (I and II) were studied by using FTIR-4100 spectrophotometer product of Jasco, Japan. The spectra were recorded from 4000 to 400 cm1. The FTIR analysis were performed in Micro analytical center, Cairo University, Egypt.
Fig. 1. Gel (%) of Poly(HEMA) and Poly(HEMA/MMA) at different comonomer composition and at comonomer concentration 40%.
Fig. 2. Effect of time on the swelling (%) of different hydrogels at comonomer concentration (a) 30%, (b) 40%, (c) 50% and (d) effect of MMA content at 50% comonomer concentration.
Fig. 3. Effect of pH on the swelling (%) of (a) Poly(HEMA), (b) Poly (HEMA/MMA) (95/5 wt %) at different pH 2,5,7.4 (c) composites I and II at pH 7.4.
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3.2. Swelling behavior The swelling properties of the prepared Poly(HEMA), and Poly(HEMA/MMA) copolymer were studied in deionized water at room temperature. The plot of swelling (%) versus time is shown in Fig. 2. The effect of time taken to obtain optimum swelling for the prepared Poly(HEMA), and Poly(HEMA/MMA) copolymer. The optimum swelling is considered as the equilibrium swelling as no further increase in swelling is observed [24]. From Fig. (2aec) as comonomer concentration increased the swelling (%) decreased due to more crosslinked Poly(HEMA/MMA) structure formed. Also from Fig. (2aec) it is found that the swelling (%) of Poly(HEMA) is slightly higher than that of Poly(HEMA/MMA) copolymer with all different composition and concentration this is due to the hydrophilic hydroxyl groups (-OH) of HEMA which are free to form H-bonding resulting slightly higher water uptake (%) Also the lower swelling (%) of the Poly(HEMA/MMA) copolymer than Poly(HEMA) due to hydrophobic character of MMA where as concentration of MMA increased swelling (%) decreased as shown in Fig. 2d. 3.3. Effect of pH on swelling behavior The effect of pH on the swelling properties of Poly(HEMA), Poly(HEMA/MMA) copolymer with composition (95/5) and composites I and II were studied and shown in Fig. 3. From Fig. 3(a, b) it was found that as pH of the medium increased the swelling % increased up to pH 7.4 this is due to formation of ionizable hydroxyl and acrylate groups in Poly(HEMA) and Poly(HEMA/MMA) copolymer. Also the swelling behavior of Poly(HEMA/MMA) is higher than that of Poly(HEMA) this is may be due to formation of more ionizable acrylate groups in Poly(HEMA/ MMA) than only acrylate groups in Poly(HEMA). In case of composites I and II, it is found that as ZnPc added to (HEMA/MMA) the swelling behavior at pH 7.4 decreased this is due to hydrophobic nature of ZnPc which containing bulky aromatic group that increased hydrophobicity due to the steric hindrance of ZnPc added to composite I therefore swelling % slightly decreased. 3.4. Fourier Transform Infrared (FTIR) 3.4.1. Fourier Transform Infrared (FTIR) of the Poly(HEMA) and Poly(HEMA-co-MMA) The FTIR of the prepared Poly(HEMA) and Poly(HEMA/MMA) copolymer with different comonomer composition were shown in Fig. 4(aed) which give information about the copolymer composition. For both Poly(HEMA) and Poly(HEMA/MMA) copolymer the characteristic peaks are similar. The absorption peaks for hydroxyl and ester carbonyl groups appeared around 3340 cm1 and 1728 cm1, the peak appeared at 2952 cm1 is corresponding to stretching of normal alkane (CH), (CH2) and (CH3). The peak at 1456 cm1 corresponds to bending of normal alkane. In case of Poly(HEMA/MMA) copolymer the peak at 1397 cm1assigned to CH3 bending. It was found that as MMA content increase the intensity of (CH), (CH2), CH3 and (C]O) peaks increased which confirm the successful copolymerization of the two monomers to form Poly(HEMA/MMA) copolymer. 3.4.2. Fourier Transform Infrared (FTIR) of composite I and II. The structure of the newly composites I and II were characterized with FTIR. Similar bands of composites I and II in Fig. (5aec) to those obtained in case of Fig. 4(aed) with addition to the bands
Fig. 4. FTIR analysis of (a) Poly(HEMA), (b) Poly(HEMA/MMA) (95/5 wt %) (c) Poly(HEMA/MMA) (90/10 wt %) and (d) Poly(HEMA/MMA) (80/20 wt %).
appearing around 1272 and 1023 cm 1 which were assigned to CeN stretching. The intensity of the previous absorption bands increases with the increasing zinc phthalocyanine. 3.5. Effect of irradiation In order to study the effect of radiation [15,16] on the prepared Poly(HEMA/MMA/ZnPc) composite I. The prepared composite I was subject to irradiation at different doses 0, 10, 30, 40 kGy. The FTIR spectra of original composite I and irradiated composite I with different doses 0, 10, 30, 40 kGy are shown in Fig. (6aed). It is clear that minor differences in FTIR spectra were observed after irradiation with different doses. Therefore the addition of zinc phthalocyanine in the repeating units of the composites I act as stabilizing agent against gamma irradiation because of delocalization of excitation energy in the
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Fig. 5. FTIR analysis of (a) Poly(HEMA/MMA) (95/5 wt %) (b) Composite I and (d) Composite II.
double and aromatic units [15,16]. Also due to large ionic radius of Zn in composites I. 3.6. Thermal analysis The thermal properties of the prepared Poly(HEMA) and Poly(HEMA/MMA) copolymer with different comonomer composition as well as their derivatives composites I and II were studied by thermogravimetric analysis (TGA) and shown in Figs. 7 and 8. Fig. 7(aed) for Poly(HEMA) and other prepared Poly(HEMA/ MMA) copolymer showed two stages of thermal decomposition. The first stage found to be around in the range of 40e125 C which corresponds to elimination of adsorbed moisture. The second step in the range of 170e440 C which correspond to major weight loss due to extensive degradation of the polymer backbone chain with maximum decomposition temperature (Tmax) 257 C for Poly(HEMA). The maximum decomposition temperature (Tmax) increased to 254, 258 and 288 C for Poly (HEMA/MMA) (95/5 wt %), (90/10 wt %) and 80/20 wt % respectively where as MMA content increased the Tmax increased. The maximum decomposition temperature (Tmax) followed by leaving a residue. The residue from the thermal decomposition of Poly(HEMA) and other prepared Poly(HEMA/MMA) copolymer left behind the maximum thermal decomposition temperature (T max), observed that, it increase with increasing MMA content due to the
Fig. 6. FTIR analysis of composite I irradiated with dose (a) 0 kGy (b) 10 kGy (b) 30 kGy and (d) 40 kGy composite I.
increase in crosslinking density. Therefore the observed maximum thermal decomposition temperature (Tmax) for the prepared copolymers refers to increase of thermal stability upon increasing MMA content. In case of composites I and II, it is clear that there are two stages of thermal decomposition Fig. 8 (aec). The first stage in the range 40e100 C, which is due to the loss of moisture followed by the second stage in the range 165e420 C which attributed to degradation of the copolymer backbone with maximum decomposition temperature (Tmax) of 254, 261.5 and 275 C for Poly (HEMA/MMA) (95/5 wt %), composites I and II respectively. It was found that the thermal stability increased with increasing the zinc phthalocyanine content.
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Fig. 7. TGA curves of (a) Poly(HEMA), (b) Poly(HEMA/MMA) (95/5 wt %) (c) Poly(HEMA/MMA) (90/10 wt %) and (d) Poly(HEMA/MMA) (80/20 wt %).
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Fig. 8. TGA curves of (a) Poly(HEMA/MMA) (95/5 wt %) (b) Composite I and (d) Composite II.
4. Conclusion A highly specific, selective and easy process control was found with the use of radiation-induced synthesis for the 2hydroxyethyl methacrylate-co-methyl methacrylate/zinc phthalocyanine Poly(HEMA/MMA/ZnPc) composites I and II was described. The prepared Poly(HEMA/MMA) and composite I and II by gamma radiation characterized by good physical, chemical, and thermal properties. Considering these promising results for easily preparation of composites I and II make the irradiation as a method of choice in the preparation of copolymers for specific practical applications such as in biomedical field and materials science [7e10]. The effect of the zinc phthalocyanine on the chemical, thermal properties and stabilization against gamma radiation of the prepared composites was discussed. It was found that curing of Poly(HEMA/MMA) by addition of low concentration of ZnPc (1 and 1.5 wt %) lead to form outstanding properties such as high thermal
and chemical stability Also it act as stabilizing agent against gamma irradiation because of delocalization of excitation energy in the double and aromatic units [15,16].
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