Swelling Behavior of Polyacrylamide Hydrogels near Phase Transition

R. R. Janot Pacheco, M. E. S. R. Silva, R. G. Sousa, R. F. S. Freitas

Chemical Engineering Department, Engineering School, Federal University of Minas Gerais, Belo Horizonte, Brazil.

DOI: 10.4236/msa.2014.58063                

Abstract

Hydrogels based on acrylamide (AA) and sodium methacrylate (NMA) as ionic monomer were prepared by solution polymerization using N,N’-methylenebis(acrylamide) (MBA) or ethylene glycol dimethacrylate (EGMA) as crosslinkers and Ammonium Persulfate (APS) and N,N,N’,N’-Te-tramethyl-ethylenediamine (TMEDA) as initiators. Swelling behavior was greatly affected by NMA content near phase transition. Increasing ionic monomer concentration compared to total monomer one led to high expansion in water, oscillating around 285 g/g for MBA and 325 g/g for EGMA crosslinker, above 20% of NMA. Dynamic Light Scattering experiments were performed and, for both crosslinkers, the dynamic correlation length (ξ) decreased with increasing NMA content, contributing to diminish hydrogels spatial inhomogeneities.

Keywords

Polyacrylamide Hydrogels, Phase Transition, Swelling Behavior, Dynamic Correlation Length

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Buchholz, F.L. and Graham, A.T. (Eds.) (1998) Modern Superabsorbent Polymer Technology. 1st Edition, WileyVCH, New York.
[2]	Zohuriaan-Mehr, M.J., Omidian, H., Doroudiani, S. and Kabiri, K. (2010) Advances in Non-Hygienic Applications of Superabsorbent Hydrogel Materials. Journal of Materials Science, 45, 5711-5735. http://dx.doi.org/10.1007/s10853-010-4780-1
[3]	Raju, K.M., Mohan, Y.M. and Raju, M.P. (2002) Synthesis and Water Absorbency of Crosslinked Superabsorbent Polymers. Journal of Applied Polymer Science, 85, 1795-1801. http://dx.doi.org/10.1002/app.10731
[4]	Raju, K.M., Mohan, Y.M., Murthy, S.P.K., Rao, K.M. and Sreeramulu, J. (2005) Swelling Behavior and Diffusion Studies of High-Water-Retaining Acrylamide/Potassium Methacrylate Hydrogels. Journal of Applied Polymer Science, 96, 1153-1164. http://dx.doi.org/10.1002/app.21565
[5]	Raju, K.M., Mohan, Y.M. and Murthy, S.K. (2005) Synthesis, Characterization and Effect of Reaction Parameters on Swelling Properties of Acrylamide-Sodium Methacrylate Superabsorbent Copolymers. Reactive and Functional Polymers, 63, 11-26. http://dx.doi.org/10.1016/j.reactfunctpolym.2005.01.005
[6]	Raju, K.M., Mohan, Y.M., P. Murthy, S.P.K. and Sreedhar, B. (2006) Swelling and Thermal Characteristics of pH Sensitive Crosslinked Poly(Acrylamide-co-Calcium Methacrylate) Superabsorbent Copolymers. Journal of Applied Polymer Science, 102, 1-12. http://dx.doi.org/10.1002/app.23562
[7]	Karadag, E., Saraydin, D. Caldiran, Y. and Güven, O. (2000) Swelling Studies of Copolymeric Acrylamide/crotonic acid Hydrogels as Carriers for Agricultural Uses. Polymers Advanced Technologies, 11, 59-68. http://dx.doi.org/10.1002/(SICI)1099-1581(200002)11:2<59::AID-PAT937>3.0.CO;2-Z
[8]	Karadag, E. and Saraydin, D. (2002) Swelling of Superabsorbent Acrylamide/Sodium Acrylate Hydrogels Prepared Using Multifunctional Crosslinkers. Turkish Journal of Chemistry, 26, 863-875.
[9]	Karadag, E., Saraydin, D. and Baris üzüm, O. (2005) Water Uptake in Chemically Crosslinked Poly(Acrylamide-coCrotonic Acid) Hydrogels. Materials & Design, 26, 265-270. http://dx.doi.org/10.1016/j.matdes.2004.07.014
[10]	Karadag, E., Kiristi, T., Kundakci, S. and Baris üzüm, O. (2010) Investigation of Sorption/swelling Characteristics of Chemically Crosslinked AAm/SMA Hydrogels as Biopotential Sorbent. Journal of Applied Polymer Science, 117, 1787-1797. http://dx.doi.org/10.1002/app.32125
[11]	Yildiz, B., Isik, B. and Kis, M. (2002) Thermoresponsive Poly(N-Isopropylacrylamide-co-Acrylamide-co-2-Hydroxyethyl Methacrylate) Hydrogels. Reactive & Functional Polymers, 52, 3-10. http://dx.doi.org/10.1016/S1381-5148(02)00035-4
[12]	Bakass, M., Bahaj, H., Benaddi, R. and Bayane, C. (2009) Swelling of Superabsorbents Polymers in an Aqueous Medium. Journal of Applied Polymer Science, 115, 2479-2484. http://dx.doi.org/10.1002/app.31030
[13]	Okay, O. and Sariisik, S.B. (2000) Swelling Behavior of Poly(Acrylamide-co-Sodium Acrylate) Hydrogels in Aqueous Salt Solutions: Theory versus Experiments. European Polymer Journal, 36, 393-399. http://dx.doi.org/10.1016/S0014-3057(99)00058-0
[14]	Wan, T., Wang, L., Yao, J., Ma, X., Yin, Q. and Zang, T. (2008) Saline Solution Absorbency and Structure Study of Poly(AA-AM) Water Superabsorbent by Inverse Microemulsion Polymarization. Polymer Bulletin, 60, 431-440. http://dx.doi.org/10.1007/s00289-007-0875-5
[15]	Okay, O., Kuru, E. A. and Orakdogen, N. (2007) Preparation of Homogeneous Polyacrylamide Hydrogels by FreeRadical Crosslinking Copolymerization. European Polymer Journal, 43, 2913-2921. http://dx.doi.org/10.1016/j.eurpolymj.2007.04.019
[16]	Leite, S.A.F. (2009) ContribuiCao ao Estudo de Polímeros Superabsorventes: Síntese e CaracterizaCao de Hidrogéis a partir da CopolimerizaCao de Acrilamida com Metacrilatos. M.Sc. Thesis, Universidade Federal de Minas Gerais, Belo Horizonte.