• Bulletin of the Korean Chemical Society
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• 제31권11호
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• pp.3163-3172
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• 2010

In this work, a novel method to synthesis of an acrylic superabsorbent hydrogel was reported. In the two stage hydrogel synthesis, first copolymerization reaction of acrylonitrile (AN) and acrylamide (AM) monomers using ammonium persulfate (APS) as a free radical initiator was performed. In the second stage, the resulted copolymer was hydrolyzed to produce carboxamide and carboxylate groups followed by in situ crosslinking of the polyacrylonitrile chains. The results from FTIR spectroscopy and the dark red-yellow color change show that the copolymerization, alkaline hydrolysis and crosslinking reactions have been do take place. Scanning electron microscopy (SEM) verifies that the synthesized hydrogels have a porous structure. The results of Brunauer-Emmett-Teller (BET) analysis showed that the average pore diameter of the synthesized hydrogel was 13.9 nm. The synthetic parameters affecting on swelling capacity of the hydrogel, such as AM/AN weight ratio and hydrolysis time and temperature, were systematically optimized to achieve maximum swelling capacity (330 g/g). The swollen gel strength of the synthesized hydrogels was evaluated via viscoelastic measurements. The results indicated that superabsorbent polymers with high water absorbency were accompanied by low gel strength. The swelling of superabsorbent hydrogels was also measured in various solutions with pH values ranging from 1 to 13. Also, the pH reversibility and on-off switching behavior makes the hydrogel as a good candidate for controlled delivery of bioactive agents. Finally, the swelling of synthesized hydrogels with various particle sizes obey second order kinetics.

• Bulletin of the Korean Chemical Society
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• 제30권11호
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• pp.2680-2686
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• 2009

The synthesis of a novel superabsorbent hydrogel with natural hybrid backbone via graft copolymerization of acrylamide (AAm) onto kappa-carrageenan (kC, as a polysaccharide) and gelatin (as a protein) under classic thermal conditions is described. The Taguchi method as a strong experimental design tool was used for synthesis optimization. A series of hydrogels were synthesized by proposed conditions of Qualitek-4 Software. Considering the results of 9 trials according to analysis of variance (ANOVA), optimum conditions were proposed. The swelling behavior of optimum hydrogel was measured in various solutions with pH values ranging from 1 to 13. In addition, swelling kinetics, swelling in various organic solvents, various salt solutions and On–Off switching behavior were investigated. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FTIR) and thermogravimetrical analysis (TGA). Surface morphology of the synthesized hydrogels was assessed by scanning electron microscope (SEM).

• Elastomers and Composites
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• 제54권3호
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• pp.201-208
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• 2019

Superabsorbent hydrogel (SAH) is a lightly crosslinked hydrophilic functional polymer material comprising a flexible chain structure, which can absorb and retain high amounts of water or aqueous fluids even under high pressure. Therefore, it is important to improve their characteristics such as absorption performance, residual monomer content, and water permeability. SAH nanocomposites were prepared using clay mineral as an inorganic filler and the influence of post-treatment processes such as quenching and aging process on their properties was studied. In addition, surface-crosslinking process was applied to improve the absorption performance associated with mechanical properties and water permeability. The structure of the SAH was characterized using attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy.

• Elastomers and Composites
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• 제54권3호
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• pp.232-240
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• 2019

A superabsorbent hydrogel (SAH) can absorb and retain water weighing more than a hundred times of their dry weight because of their three-dimensional hydrophilic structure. To fabricate an SAH, itaconic acid (IA) and vinyl sulfonic acid (VSA) were subjected to radical polymerization in an aqueous solution, wherein IA and VSA were neutralized, and then, a crosslinker and a thermal initiator were added in sequence. The structure of poly(IA-co-VSA) was characterized using attenuated total reflectance Fourier-transform infrared spectroscopy. We also studied the changes in the absorption properties of the SAH composites according to the polymerization temperature, degree of neutralization, type and content of the initiator used, and type and content of the crosslinker used. Thus, we could determine the effects of some synthetic factors on the absorption properties of the SAH.

• Macromolecular Research
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• 제13권6호
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• pp.483-490
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• 2005

A novel, polysaccharide-based, superabsorbent hydrogel was synthesized through crosslinking graft copolymerization of methacrylic acid (MAA) onto kappa-carrageenan ($_{k}C$), using ammonium persulfate (APS) as a free radical initiator in the presence of methylenebisacrylamide (MBA) as a crosslinker. A proposed mechanism for $_{k}C$­g-polymethacrylic acid ($_{k}C$-g-PMAA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy. The effect of grafting variables, including MBA, MAA, and APS concentration, was systematically optimized to achieve a hydrogel with the maximum possible swelling capacity. The swelling kinetics in distilled water and various salt solutions were preliminarily investigated. Absorbency in aqueous salt solutions of lithium chloride, sodium chloride, potassium chloride, calcium chloride, and aluminum chloride indicated that the swelling capacity decreased with increased ionic strength of the swelling medium. This behavior can be attributed to the charge screening effect for monovalent cations, as well as ionic crosslinking for multivalent cations. The swelling of super absorbing hydrogels was measured in solutions with pH ranging from 1 to 13. In addition, the pH reversibility and on-off switching behavior, at pH levels of 3.0 and 8.0, give the synthesized hydrogels great potential as an excellent candidate for the controlled delivery of bioactive agents.

• 한국결정성장학회지
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• 제32권3호
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• pp.107-114
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• 2022

Carboxymethyl cellulose/poly(ethylene glycol) (CMC/PEG) hydrogels crosslinked with citric acid (CA) are synthesized to evaluate the effect of CMC molecular weight (Mw), PEG and CA concentration on the optical property, swelling rate (SR), degradation rate (DR), and cytotoxicity and cell proliferation of hydrogels. For crosslinked CMC/PEG hydrogels, the FT-IR peak intensity associated with hydroxyl groups decreases due to PEG intercalation (esterification crosslinking) between CMC chains in a similar manner as the concentration of CA crosslinker increases. Crosslinked CMC (Mw = 90,000)/PEG hydrogels with 10 % CA dissolve regardless of PEG content. However, the SR of the CMC (Mw = 250,000)/PEG hydrogels decrease from 4923 % to 168 % with increasing PEG and CA concentrations from 0 to 20 % and from 0 to 25 %, respectively. As the Mw of CMC increases, the DR of the hydrogel is greatly improved. CMC (Mw = 250,000)/PEG10 hydrogels with 10 % CA exhibit the optimum properties of high absorbing capacity (3,200 %) with moderate DR (54 %), stiffness (1.39 ± 0.19 GPa), and cell viability (94.8 ± 1.3 %). CA-crosslinked CMC/PEG hydrogels are highly suitable for wound dressing or personal care applications due to their non-toxicity, good cell proliferation, SR, and mechanical properties.

• Macromolecular Research
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• 제13권1호
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• pp.45-53
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• 2005

In this study, a series of highly swelling hydrogels based on sodium alginate (NaAlg) and polymethacryl­amide (PMAM) was prepared through free radical polymerization. The graft copolymerization reaction was performed in a homogeneous medium and in the presence of ammonium persulfate (APS) as an initiator and N,N'-methylenebis­acrylamide (MBA) as a crosslinker. The crosslinked graft copolymer, alginate-graft-polymethacrylamide (Alg-g­PMAM), was then partially hydrolyzed by NaOH solution to yield a hydrogel, hydrolyzed alginate-graft-poly­methacrylamide (H-Alg-g-PMAM). During alkaline hydrolysis, the carboxamide groups of Alg-g-PMAM were converted into hydrophilic carboxylate anions. Either the Alg-g-PMAM or the H-Alg-g-PMAM was characterized by FTIR spectroscopy. The effects of the grafting variables (i.e., concentration of MBA, MAM, and APS) and the alkaline hydrolysis conditions (i.e., NaOH concentration, hydrolysis time, and temperature) were optimized systematically to achieve a hydrogel having the maximum swelling capacity. Measurements of the absorbency in various aqueous salt solutions indicated that the swelling capacity decreased upon increasing the ionic strength of the swelling medium. This behavior could be attributed to a charge screening effect for monovalent cations, as well as ionic cross-linking for multivalent cations. Because of the high swelling capacity in salt solutions, however, the hydrogels might be considered as anti-salt superabsorbents. The swelling behavior of the superabsorbing hydrogels was also measured in solutions having values of pH ranging from 1 to 13. Furthermore, the pH reversibility and on/off switching behavior, measured at pH 2.0 and 8.0, suggested that the synthesized hydrogels were excellent candidates for the controlled delivery of bioactive agents. Finally, we performed preliminary investigations of the swelling kinetics of the synthesized hydrogels at various particle sizes.

• Fibers and Polymers
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• 제5권2호
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• pp.95-104
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• 2004

A series of superabsorbents based on acrylic acid (AA), sodium acrylate, 2-acrylamido-2-methylpropane sulphonic acid, N,N'-methylene bis-acrylamide (MBA) were prepared by inverse suspension polymerization. These hydrogels were further crosslinked on the surface with polyethylene glycol-600 (PEG-600). The water absorbency or swelling behaviors for these xerogels in water and 0.9% saline solutions, both under free condition and under load were investigated. Absorption characteristics of these hydrogels were found to depend on nature and concentration of crosslinker in the system. It was also found that the saline absorption was significantly improved as the incorporation of AMPS in the polymer was increased. The surface crosslinking introduced in the polymers was found to improve the absorption under load characteristics without lowering the free water absorption capacities of the polymer to a considerable extent.

• 폴리머
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• 제33권5호
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• pp.469-476
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• 2009

본 연구에서는 속팽윤성과 고흡수성을 갖는 초다공성 수화젤의 제조과정에서 생분해성 가교제를 이용하여 생분해성 초다공성 수화젤을 제조하고 특성분석을 수행하였다. 친수성 고분자인 poly(ethylene glycol)의 양말단에 D,L-lactide를 개환 중합시켜 PLA-PEG-PLA 삼중공중합체를 합성한 뒤, 양말단에 비닐기를 도입하여 생분해성 가교제를 합성하였다. 조성이 다양한 초다공성 수화젤을 제조하여 각각의 팽윤도, 팽윤속도 및 생분해성을 비교하였다. 중합된 고분자의 화학적 조성을 $^1H$-NMR, GPC, FT-IR 측정을 통해 확인하였고, 수화젤 표면 및 내부의 SEM 분석을 통해 수 백 ${\mu}m$ 크기의 공극들로 생성된 열린 채널구조의 초다공성 구조를 관찰하였다. 수은 다공도계로 수화절의 기공크기와 다공도를 측정하였고, 조성에 따라 물리회학적 성질이 조절될 수 있음을 알 수 있었으며, MTT분석에 의해 낮은 세포독성을 나타냄을 확인하였다.

• 폴리머
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• 제35권6호
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• pp.558-564
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• 2011

생체적합하고 생분해성을 갖는 폴리아미노산의 하나인 폴리아스팔트산은 팹타이드 결합으로 이루어진 수용성 합성고분자로서 의료용 소재 및 다양한 응용분야의 연구가 흥미있게 진행되어 왔다. 본 연구에서는 아미노산인 GABA(${\gamma}$-aminobutylic acid)와 ${\beta}$-alanine을 곁사슬에 도입한 폴리아스팔트산 유도체 고분자를 제조하고, 이들을 서로 다른 함량의 ethylene glycol diglycidyl ether(EGDE)를 사용하여 가교시켜 고흡수성 하이드로젤을 제조하였다. 각 하이드로젤에 대해 증류수와 PBS 용액에서 기본적인 팽윤물성, 젤의 가수분해 거동과 모폴로지를 조사하였다. 제조한 하이드로젤은 수용액에서 pH와 염(salt) 농도에 의존하는 민감성 팽윤거동을 보였으며, 또한 비교적 빠른 가수분해 거동을 나타내었다.