journal article Open Access Jul 29, 2024

Crosslinking and Swelling Properties of pH-Responsive Poly(Ethylene Glycol)/Poly(Acrylic Acid) Interpenetrating Polymer Network Hydrogels

Polymers Vol. 16 No. 15 pp. 2149 · MDPI AG
View at Publisher Save 10.3390/polym16152149
Abstract
This study investigates the crosslinking dynamics and swelling properties of pH-responsive poly(ethylene glycol) (PEG)/poly(acrylic acid) (PAA) interpenetrating polymer network (IPN) hydrogels. These hydrogels feature denser crosslinked networks compared to PEG single network (SN) hydrogels. Fabrication involved a two-step UV curing process: First, forming PEG-SN hydrogels using poly(ethylene glycol) diacrylate (PEGDA) through UV-induced free radical polymerization and crosslinking reactions, then immersing them in PAA solutions with two different molar ratios of acrylic acid (AA) monomer and poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker. A subsequent UV curing step created PAA networks within the pre-fabricated PEG hydrogels. The incorporation of AA with ionizable functional groups imparted pH sensitivity to the hydrogels, allowing the swelling ratio to respond to environmental pH changes. Rheological analysis showed that PEG/PAA IPN hydrogels had a higher storage modulus (G′) than PEG-SN hydrogels, with PEG/PAA-IPN5 exhibiting the highest modulus. Thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated increased thermal stability for PEG/PAA-IPN5 compared to PEG/PAA-IPN1, due to higher crosslinking density from increased PEGDMA content. Consistent with the storage modulus trend, PEG/PAA-IPN hydrogels demonstrated superior mechanical properties compared to PEG-SN hydrogels. The tighter network structure led to reduced water uptake and a higher gel modulus in swollen IPN hydrogels, attributed to the increased density of active network strands. Below the pKa (4.3) of acrylic acid, hydrogen bonds between PEG and PAA chains caused the IPN hydrogels to contract. Above the pKa, ionization of PAA chains induced electrostatic repulsion and osmotic forces, increasing water absorption. Adjusting the crosslinking density of the PAA network enabled fine-tuning of the IPN hydrogels’ properties, allowing comprehensive comparison of single network and IPN characteristics.
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References
42
[1]
Gu, Z., Huang, K., Luo, Y., Zhang, L., Kuang, T., Chen, Z., and Liao, G. (2018). Double Network Hydrogel for Tissue Engineering. Wiley Interdiscip. Rev. Nanomed. Nanobiotechnol., 10. 10.1002/wnan.1520
[2]
Hu "Advances in Crosslinking Strategies of Biomedical Hydrogels" Biomater. Sci. (2019) 10.1039/c8bm01246f
[3]
Aswathy "Commercial Hydrogels for Biomedical Applications" Heliyon (2020) 10.1016/j.heliyon.2020.e03719
[4]
Sánchez-Cid, P., Jiménez-Rosado, M., Romero, A., and Pérez-Puyana, V. (2022). Novel Trends in Hydrogel Development for Biomedical Applications: A Review. Polymers, 14. 10.3390/polym14153023
[5]
Suhail, M., Fang, C.W., Chiu, I.H., Hung, M.C., Vu, Q.L., Lin, I.L., and Wu, P.C. (2022). Designing and In Vitro Characterization of pH-Sensitive Aspartic Acid-Graft-Poly (Acrylic Acid) Hydrogels as Controlled Drug Carriers. Gels, 8. 10.3390/gels8080521
[6]
Hydrogel design strategies for drug delivery

Cécile A. Dreiss

Current Opinion in Colloid & Interface Science 2020 10.1016/j.cocis.2020.02.001
[7]
Briggs, F., Browne, D., and Asuri, P. (2022). Role of Polymer Concentration and Crosslinking Density on Release Rates of Small Molecule Drugs. Int. J. Mol. Sci., 23. 10.3390/ijms23084118
[8]
Hunt "Hydrogels for Tissue Engineering and Regenerative Medicine" J. Mater. Chem. B (2014) 10.1039/c4tb00775a
[9]
Crosby "Interpenetrating Polymer Network Hydrogels as Bioactive Scaffolds for Tissue Engineering" Rev. Chem. Eng. (2022) 10.1515/revce-2020-0039
[10]
Huang "Research Progress on Double-Network Hydrogels" Mater. Today Commun. (2021) 10.1016/j.mtcomm.2021.102757
[11]
Nonoyama "Tough Double Network Hydrogel and Its Biomedical Applications" Annu. Rev. Chem. Biomol. Eng. (2021) 10.1146/annurev-chembioeng-101220-080338
[12]
Haraguchi "Nanocomposite Hydrogels: A Unique Organic–Inorganic Network Structure with Extraordinary Mechanical, Optical, and Swelling/De-Swelling Properties" Adv. Mater. (2002) 10.1002/1521-4095(20020816)14:16<1120::aid-adma1120>3.0.co;2-9
[13]
Double‐Network Hydrogels with Extremely High Mechanical Strength

J.P. Gong, Y. Katsuyama, T. Kurokawa et al.

Advanced Materials 2003 10.1002/adma.200304907
[14]
Why are double network hydrogels so tough?

Jian Ping Gong

Soft Matter 2010 10.1039/b924290b
[15]
Nakayama "High Mechanical Strength Double-Network Hydrogel with Bacterial Cellulose" Adv. Funct. Mater. (2004) 10.1002/adfm.200305197
[16]
Myung "Biomimetic Strain Hardening in Interpenetrating Polymer Network Hydrogels" Polymer (2007) 10.1016/j.polymer.2007.06.070
[17]
Weng "Mechanically Strong Double Network Photocrosslinked Hydrogels from N, N-Dimethylacrylamide and Glycidyl Methacrylated Hyaluronan" Biomaterials (2008) 10.1016/j.biomaterials.2008.01.012
[18]
Jayaramudu "Preparation and Characterization of Poly (Ethylene Glycol) Stabilized Nano Silver Particles by a Mechanochemical Assisted Ball Mill Process" J. Appl. Polym. Sci. (2016) 10.1002/app.43027
[19]
Jung "Effects of Solvents on Rheological and Crosslinking Properties of Photo-Polymerized Poly (Ethylene Glycol) Hydrogels" Korean J. Chem. Eng. (2017) 10.1007/s11814-017-0013-5
[20]
Sabel-Grau, T., Tyushina, A., Babalik, C., and Lensen, M.C. (2022). UV-VIS Curable PEG Hydrogels for Biomedical Applications with Multifunctionality. Gels, 8. 10.3390/gels8030164
[21]
Hu "Preparation and Characterization of a Novel pH-Sensitive Salecan-g-Poly (Acrylic Acid) Hydrogel for Controlled Release of Doxorubicin" J. Mater. Chem. B (2015) 10.1039/c5tb00264h
[22]
Zhou "Hydrolysis-Induced Large Swelling of Polyacrylamide Hydrogels" Soft Matter (2020) 10.1039/d0sm00663g
[23]
Myung "Glucose-Permeable Interpenetrating Polymer Network Hydrogels for Corneal Implant Applications: A Pilot Study" Curr. Eye Res. (2008) 10.1080/02713680701793930
[24]
Myung "Bioactive Interpenetrating Polymer Network Hydrogels That Support Corneal Epithelial Wound Healing" J. Biomed. Mater. Res. Part A (2009) 10.1002/jbm.a.32056
[25]
Yim "Biocompatibility of Poly (Ethylene Glycol)/Poly (Acrylic Acid) Interpenetrating Polymer Network Hydrogel Particles in RAW 264.7 Macrophage and MG-63 Osteoblast Cell Lines" J. Biomed. Mater. Res. Part A (2009) 10.1002/jbm.a.32311
[26]
Waters "Structure and Mechanism of Strength Enhancement in Interpenetrating Polymer Network Hydrogels" Macromolecules (2011) 10.1021/ma200693e
[27]
Naficy "A pH-Sensitive, Strong Double-Network Hydrogel: Poly (Ethylene Glycol) Methyl Ether Methacrylates–Poly (Acrylic Acid)" J. Polym. Sci. Part B Polym. Phys. (2012) 10.1002/polb.23016
[28]
Tan "In Vivo Biocompatibility of Two PEG/PAA Interpenetrating Polymer Networks as Corneal Inlays Following Deep Stromal Pocket Implantation" J. Mater. Sci. Mater. Med. (2013) 10.1007/s10856-012-4848-3
[29]
Hwang "Gelation and Crosslinking Characteristics of Photopolymerized Poly (Ethylene Glycol) Hydrogels" J. Appl. Polym. Sci. (2015) 10.1002/app.41939
[30]
Park, J., Kim, N., Jung, K.I., Yoon, S., Noh, S.M., Bang, J., and Jung, H.W. (2021). Effect of Silica Nanoparticles Blocked with Epoxy Groups on the Crosslinking and Surface Properties of PEG Hydrogel Films. Polymers, 13. 10.3390/polym13193296
[31]
Sung, J., Lee, D.G., Lee, S., Park, J., and Jung, H.W. (2020). Crosslinking Dynamics and Gelation Characteristics of Photo-and Thermally Polymerized Poly (Ethylene Glycol) Hydrogels. Materials, 13. 10.3390/ma13153277
[32]
Myung "Progress in the Development of Interpenetrating Polymer Network Hydrogels" Polym. Adv. Technol. (2008) 10.1002/pat.1134
[33]
Wen "Preparation and Characterization of Konjac Glucomannan–Poly (Acrylic Acid) IPN Hydrogels for Controlled Release" Carbohydr. Polym. (2009) 10.1016/j.carbpol.2009.04.001
[34]
Yang "Chain-Extended Polyurethane–Acrylate Ionomer for UV-Curable Waterborne Coatings" J. Appl. Polym. Sci. (2002) 10.1002/app.10384
[35]
Dave "Synthesis and Characterization of Interpenetrating Polymer Networks from Transesterified Castor Oil Based Polyurethane and Polystyrene" J. Saudi Chem. Soc. (2017) 10.1016/j.jscs.2013.08.001
[36]
Guo, Q. (2012). Thermal Properties of Thermosets. Thermosets, Woodhead Publishing. 10.1533/9780857097637
[37]
"Glass Transition in Homogeneous and Heterogeneous Interpenetrating Polymer Networks and Its Relation to Concentration Fluctuations" J. Non-Cryst. Solids (2002)
[38]
Moon "Thermal Crosslinking Characteristics of Dual-Curable Isocyanate Blocked with Methacrylate-Functionalized Amine Derivatives for Eco-Friendly Automotive Clearcoats" Appl. Surf. Sci. (2023) 10.1016/j.apsusc.2022.155058
[39]
June "Influence of Functional Group Content in Hydroxyl-Functionalized Urethane Methacrylate Oligomers on the Crosslinking Features of Clearcoats" J. Coat. Technol. Res. (2021) 10.1007/s11998-020-00398-1
[40]
Ninciuleanu, C.M., Ianchiş, R., Alexandrescu, E., Mihăescu, C.I., Scomoroşcenco, C., Nistor, C.L., Preda, S., Petcu, C., and Teodorescu, M. (2021). The Effects of Monomer, Crosslinking Agent, and Filler Concentrations on the Viscoelastic and Swelling Properties of Poly (Methacrylic Acid) Hydrogels: A Comparison. Materials, 14. 10.3390/ma14092305
[41]
Sorkhabi, T.S., Samberan, M.F., Ostrowski, K.A., and Majka, T.M. (2022). Novel Synthesis, Characterization and Amoxicillin Release Study of pH-Sensitive Nanosilica/Poly (Acrylic Acid) Macroporous Hydrogel with High Swelling. Materials, 15. 10.3390/ma15020469
[42]
Li "A Non-Gaussian Model for the Chemo-Mechanical Coupling Behavior of Largely Deformed Hydrogels" Soft Mater. (2019) 10.1080/1539445x.2019.1568260
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References
Details
Published
Jul 29, 2024
Vol/Issue
16(15)
Pages
2149
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Funding
Ministry of Trade, Industry, and Energy (MOTIE, Korea) under the Industrial Technology Innovation Program Award: 20010256
National Research Foundation of Korea (NRF) of the Ministry of Science and ICT (MSIT) of the Korean government Award: 20010256
Cite This Article
Uijung Hwang, HoYeon Moon, Junyoung Park, et al. (2024). Crosslinking and Swelling Properties of pH-Responsive Poly(Ethylene Glycol)/Poly(Acrylic Acid) Interpenetrating Polymer Network Hydrogels. Polymers, 16(15), 2149. https://doi.org/10.3390/polym16152149
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