In this article, we synthesize of a novel starch-based superabsorbent hydrogel via graft copolymerization of mixtures of acrylic acid (AA) and 2-Hydroxy ethyl methacrylate (HEMA) onto starch backbones. The polymerization reaction was carried out in an aqueous medium and in the presence of ammonium persulfate (APS) as an initiator and N , N ’-methylene bisacrylamide (MBA) as a crosslinker. The hydrogel structures were confirmed by FTIR spectroscopy. Furthermore, the swelling of superabsorbing hydrogels was examined in solutions with pH values ranging between 1 and 13. It showed a reversible pH-responsive behavior at pHs 2 and 8. This on-off switching behavior makes the synthesized hydrogels as an excellent candidate for controlled delivery of bioactive agents. A proposed mechanism for hydrogel formation was suggested and the structure of the product was established using FTIR and SEM spectroscopies.
D. C. Hwang, S. Damodaran, “Synthesis and Properties of Fish Protein-Based Hydrogel,” Journal of the American Oil Chemists’ Society, Vol. 74, No. 9, 1997, pp. 1165-1171.
J. Kost, “Encyclopedia of Controlled Drug Delivery,” Vol. 1, Wiley, New York, 1999, p. 445.
A. S. Hoffman, “Polymeric Materials Encyclopedia,” Vol. 5, CRC Press, Boca Raton, 1996, p. 3282.
N. A. Peppas, A. G. Mikes, “Hydrogels in Medicine and Pharmacy,” Vol. 1, CRC Press, Boca Raton, 1986.
D. W. Jenkins, S. M. Hudson, “Review of Vinyl Graft Copolyme-rization Featuring Recent Advances toward Controlled Radical-Based Reactions and Illustrated with Chitin/Chitosan Trunk Polymers,” Chemical Reviews, Vol. 101, No. 11, 2001, pp. 3245-3273. doi:10.1021/cr000257f
N. Miyata, M. Yokoyama, I. Sakata, “Properties of Highly Water-Absorptive Hydroxyethyl-cellulose Graft Copolymers: Viscoelasticity and Moisture Sorption,” Journal of Applied Polymer Science, Vol. 55, No. 2, 1995, pp. 201-208. doi:10.1002/app.1995.070550202
E. Rezai and R. R. Warner, “Polymer-Grafted Cellulose Fibers. I. Enhanced Water Absorbency and Tensile Strength,” Journal of Applied Polymer Science, Vol. 65, No. 8, 1997, pp. 1463-1469. doi:10.1002/(SICI)1097-4628(19970822)65:8 3.0.CO;2-E
N. Miyata, M. Yokoyama and I. Sakata, “Properties of Highly Water-Absorptive Hydroxyethylcellulose Graft Copolymers: Viscoelasticity and Moisture Sorption,” Journal of Applied Polymer Science, Vol. 55, No. 2, 1995, pp. 201-208. doi:10.1002/app.1995.070550202
J. C. Salamone, E. L. Rodriguez, K. C. Lin, L. Quach, A. C. Watterson and I. Ahmad, “Aqueous Salt Absorption by Ampholytic Poly-saccharides,” Polymer, Vol. 26, No. 8, 1985, pp. 1234-1238. doi:10.1016/0032-3861(85)90259-9
G. F. Fanta, “Polymeric Materials Encyclopedia,” Vol. 10, CRC Press, Boca Raton, 1996, p. 7901, 8051.
Y. Zhu, B. Pu, J. Zhang and J. Shen, “Synthesis of Anti-Salt Absorbent Resins and Studies of Reaction Mechanism,” Journal of Applied Polymer Science, Vol. 79, No. 3, 2001, pp. 572-574. doi:10.1002/1097-4628(20010118)79:3 3.0.CO;2-T
Y.-J. Kim, K. J. Yoon and S. W. Ko, “Preparation and Properties of Alginate Superabsorbent Filament Fibers Crosslinked with Glutaraldehyde,” Journal of Applied Polymer Science, Vol. 78, No. 10, 2000, pp. 1797-1804. doi:10.1002/1097-4628(20001205)78:10 3.0.CO;2-M
H. T. Lokhande, P. V. Varadarajan and V. Iyer, “Water-Superabsorbent Polymers through Gamma Radiation- Induced Graft-Copolymerization of Acrylonitrile on Guargum,” Journal of Applied Polymer Science, Vol. 45, No. 11, 1992, pp. 2031-2036. doi:10.1002/app.1992.070451117
V. D. Athawale and V. L. Lele, “Recent Trends in Hydrogels Based on Starch-graft-Acrylic Acid: A Review,” Starch/Starke, Vol. 53, No. 1, 2001, pp. 7-13. doi:10.1002/1521-379X(200101)53:1 3.0.CO;2-Q
Y. Sugahara and O. Takahisa, “Synthesis of Starch-Graft-Polyacrylonitrile Hydrolyzate and Its Characterization,” Journal of Applied Polymer Science, Vol. 82, No. 6, 2001, pp. 1437-1443. doi:10.1002/app.1981
M. Yamaguchi, H. Watamoto and M. Sakamoto, “Super Absorbent Polymers from Mixtures of Polyacrylonitrile and Saccharides,” Carbohydrate Polymers, Vol. 9, No. 1, 1988, pp. 15-23. doi:10.1016/0144-8617(88)90074-4
C. Rodehed and B. Ranby, “Structure and Molecular Properties of Saponified Starch-Graft-Polyacrylonitrile,” Journal of Applied Polymer Science, Vol. 32, No. 1, 1986, pp. 3323-3333. doi:10.1002/app.1986.070320134
D. W. Lim, H. S. Whang and K. J. Yoon, “Synthesis and Absorbency of a Superabsorbent from Sodium Starch Sulfate-g-Polyacrylonitrile,” Journal of Applied Polymer Science, Vol. 79, No. 8, 2001, pp. 1423-1430. doi:10.1002/1097-4628(20010222)79:8 3.0.CO;2-V
M. O. Weaver, L. A. Gugliemeli, W. M. Doane and C. R. Russel, “Hydrolyzed Starch-Polyacrylonitrile Graft Copolymers: Effect of Structure on Properties,” Journal of Applied Polymer Science, Vol. 15, No. 12, 1971, pp. 3015-3024. doi:10.1002/app.1971.070151211
R. M. Silverstein, F. X. Webster, “Spectrometric Identification of Organic Compounds,” 6th edition, Wiley, New York, 1998.
E. Sjostrom, “Fundamental of Carbohydrate Chemistry and Wood Chemistry: Fundamentals and Applications,” Academic, San Diego, 1981.
P. J. Flory, “Principles of Polymer Chemistry,” Cornell University Press, Ithaca, New York, 1953.
D. Castel, A. Ricard and R. Audebert, “Swelling of Anionic and Cationic Starch-Based Superabsorbents in Water and Saline Solution,” Journal of Applied Polymer Science, Vol. 39, No. 1, 1990, pp. 11-29. doi:10.1002/app.1990.070390102
G. R. Mahdavinia, A. Pourjavadi and M. J. Zohuriaan-Mehr, “Modified Chitosan III, Superabsorbency, Salt- and pH-sensitivity of Smart Ampholytic Hydrogels from Chitosan-g-PAN,” Polymers for Advanced Technologies, Vol. 15, No. 4, 2004, pp. 173-180. doi:10.1002/pat.408
J. J. Hermans, “Flow Properties of Disperse Systems,” Wiley Interscience, New York, 1953.
W. F. Lee and W. Y. Yuan, “Thermoreversible Hydrogels X: Synthesis and Swelling Behavior of the (N-isopropy-lacrylamide-co-sodium 2-acrylamido-2-methylpropyl sulfonate) Copolymeric Hydrogels,” Journal of Applied Polymer Science, Vol. 77, No. 8, 2000, pp. 1760-1768. doi:10.1002/1097-4628(20000822)77:8 3.0.CO;2-J
S. E. Park, Y. C. Nho, Y. M. Lim and H. Kim, “Preparation of pH-Sensitive Poly(vinyl alcohol-g-methacrylic acid) and Poly(vinyl alcohol-g-acrylic acid) Hydrogels by Gamma Ray Irradiation and Their Insulin Release Behavior,” Journal of Applied Polymer Science, Vol. 91, No. 1, 2004, pp. 636-643. doi:10.1002/app.13211
K. Burugapalli, D. Bhatia, V. Koul and V. Choudhary, “Interpenetrating Polymer Networks Based on Poly (acrylic acid) and Gelatin. I: Swelling and Thermal Behavior,” Journal of Applied Polymer Science, Vol. 82, No. 1, 2001, pp. 217-227. doi:10.1002/app.1841
S. Lu, M. Duan and S. Lin, “Superabsorbent Polymeric Materials VIII: Swelling Behavior of Crosslinked Poly [sodium acrylate-co-trimethyl methacryloyloxyethyl ammonium iodide] in Aqueous Salt Solutions,” Journal of Applied Polymer Science, Vol. 79, No. 9, 2001, pp. 1665-1674. doi:10.1002/1097-4628(20010228)79:9 3.0.CO;2-P
A. Pourjavadi, M. Sadeghi and H. Hosseinza-deh, “Modified Carrageenan. 5. Preparation, Swelling Behavior, Salt- and pH-Sensitivity of Partially Hydrolyzed Crosslinked Carrageenan-graft-polymethacrylamide Superabsorbent Hydrogel,” Polymers for Advanced Technologies, Vol. 15, No. 11, 2004, pp. 645-653. doi:10.1002/pat.524
A. M. Lowman and N. A. Peppas, “Encyclopedia of Controlled Drug Delivery,” Wiley, New York, 1999, p. 139.
A. Richter, A. Bund, M. Keller and K. Arndt, “Characterization of a Microgravimetric Sensor Based on pH Sensitive Hydrogels,” Sensors and Actuators B: Chemical, Vol. 99, No. 2-3, 2004, pp. 579-585. doi:10.1016/j.snb.2004.01.011
L. H. Gan, G. R. Deen, Y. Y. Gan and K. C. Tam, “Water Sorption Studies of New pH-Responsive N-acryloyl-N′- methyl piperazine and Methyl Methacrylate Hydrogels,” European Polymer Journal, Vol. 37, No. 7, 2001, pp. 1473-1478. doi:10.1016/S0014-3057(00)00250-0
F. L. Buchholz, “Superabsorbent Polymers: Science and Technology,” In: F. L. Buchholz and N. A. Peppas, Eds., ACS Symposium Series 573, American Chemical Society, Washington DC, 1994.