Person: TUNCABOYLU, DENIZ CEYLAN
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Publication Porous rubber cryogels: effect of the gel preparation temperature(2014-08-01T00:00:00Z) Oztoprak, Zeynep; Hekimoglu, Tugce; Karakutuk, Ilknur; Tuncaboylu, Deniz C.; Okay, Oğuz; TUNCABOYLU, DENIZ CEYLANThis paper examines the effect of the gel preparation temperature (T (prep)) on the physical properties of the rubber-based macroporous organogels prepared by solution crosslinking in benzene at subzero temperatures. Cis-polybutadiene (CBR) and styrene-butadiene rubber (SBR) were used as the rubber components, while sulfur monochloride (S2Cl2) was the crosslinker in the gel preparation. It was shown that T (prep) is an extremely important parameter to adjust the porous structure and thus, the cryogel properties. The networks formed by CBR and SBR showed an aligned porous structure with an exception of honey-comb structured porous SBR cryogels prepared at -2 A degrees C. 10(1)- to 10(2)-mu m sized regular pores of the networks caused by the benzene crystals act as a template during gelation, separated by 10-20 mu m pore walls in thickness. They exhibit fast swelling and deswelling properties as well as reversible swelling-deswelling cycles in toluene and methanol, respectively. The ability of the organogels for the removal of petroleum products from aqueous solutions was also demonstrated using diesel and crude oil as model pollutants. In addition, the reusability of the organogels and their continuous sorption capacities were checked by repeated sorption-squeezing cycles. All the tests showed that the aligned porous organogels are suitable materials for the oil spill cleanup procedures.Publication Structure optimization of self-healing hydrogels formed via hydrophobic interactions(2012-11-09T00:00:00Z) Tuncaboylu, Deniz C.; Argun, Aslihan; Sahin, Melahat; Sari, Murat; Okay, Oğuz; TUNCABOYLU, DENIZ CEYLANIn an attempt to mimic self-healing functions in biological systems, we investigate here the optimum design parameters of self-healing hydrogels formed by hydrophobic associations in aqueous solutions of wormlike sodium dodecyl sulfate (SDS) micelles. n-alkyl (meth)acrylates were used as the hydrophobic comonomer (2 mol %) of acrylamide in the gel preparation. Two structural parameters are crucial for obtaining self-healing gels via hydrophobic interactions. One is the length of the alkyl side chain of the hydrophobe, and the other is the surfactant concentration. In addition, hydrophobic methacrylates generate gels with a higher healing efficiency than the corresponding acrylates due to the limited flexibility of the methacrylate backbones, leading to a greater number of non-associated hydrophobic blocks. These free blocks locating near the fracture surface of the gel samples link each other to self-heal the broken hydrogel. The physical gels without SDS are very tough due to their sacrificial bonds that are broken under force and preventing the fracture of the molecular backbone. (C) 2012 Elsevier Ltd. All rights reserved.Publication Pluronic Based Injectable Smart Gels with Coumarin Functional Amphiphilic Copolymers(2022-06-01T00:00:00Z) Alemdar, Mahinur; Tuncaboylu, Deniz Ceylan; Batu, Hatice Kubra; Temel, Binnur; TUNCABOYLU, DENIZ CEYLAN; TEMEL, BİNNURPublication Şekil Hafızalı ve Kendini Onarabilen Hidrojeller(2021-10-08T00:00:00Z) Kılıç, Hüsna; Tuncaboylu, Deniz Ceylan; Argun, Aslı; Öztürk Civelek, Dilek; TUNCABOYLU, DENIZ CEYLAN; ÖZTÜRK CİVELEK, DİLEK.Publication Tough interpenetrating Pluronic F127/polyacrylic acid hydrogels(2013-05-01T00:00:00Z) Baskan, Tuba; Tuncaboylu, Deniz C.; Okay, Oğuz; TUNCABOYLU, DENIZ CEYLANTough interpenetrating polymer network (IPN) hydrogels with pH- and temperature sensitivity were prepared by crosslinking copolymerization of acrylic acid (AAc) and N,N--methylenebis(acrylamide) in 20 w/v% aqueous solutions of F127 (PEO99-PPO65-PEO99). The presence of F127 within the gel network slightly decreases the elastic modulus while the loss factor significantly increases, revealing increasing energy dissipation in IPN hydrogels. Cyclic compression tests show large mechanical hysteresis in IPN hydrogels due to the reversible formation of ionic clusters and hydrophobic associations of F127 molecules. The dissipative mechanisms created by F127 lead to the improvement in the mechanical performance of IPN hydrogels when compared to the polyacrylic acid (PAAc) gel controls. PAAc hydrogel formed at 10% AAc fractures under a compression of 0.2 MPa at 78% strain, while the corresponding IPN hydrogel sustains up to 7 MPa compressions at 98% strain, leading to an increase of toughness from 31 to 335 kJ/m(3). IPN hydrogels subjected to the heating-cooling cycles between below and above the micellization temperature of F127 show characteristic features of F127 solutions, i.e., increase of the dynamic moduli on raising the temperature, and thermal hysteresis behavior. (c) 2013 Elsevier Ltd. All rights reserved.Publication Surfactant-induced healing of tough hydrogels formed via hydrophobic interactions(2014-02-01T00:00:00Z) Argun, Aslihan; Algi, Melek Pamuk; Tuncaboylu, Deniz C.; Okay, Oğuz; TUNCABOYLU, DENIZ CEYLANDifferent reversible molecular interactions have been used in the past few years to generate self-healing in synthetic hydrogels. However, self-healing hydrogels synthesized so far suffer from low mechanical strength which may limit their use in any stress-bearing applications. Here, we present a simple technique to heal mechanically strong polyacrylamide hydrogels formed via hydrophobic interactions between stearyl groups. A complete healing in the hydrogels was achieved by the treatment of the damaged areas with an aqueous solution of wormlike sodium dodecyl sulfate micelles. The micelles in the healing agent solubilize the hydrophobes in the cut surfaces, so that they easily find their partners in the other cut surface due to the hydrophobic interactions. Surfactant-induced healing produces high toughness (similar to 1 MPa) gels withstanding 150 kPa of stress at a deformation ratio of 1,100 %. The healing technique developed here is generally applicable to the physical gels formed by hydrophobic associations.Publication MICROGELS FROM PHOTOCROSSLINKING OF CINNAMYLIDENE ACETIC ACID MODIFIED POLYETHYLENE GLYCOL(2016-03-14T00:00:00Z) wischke, christian; CEYLAN TUNCABOYLU, DENİZ; LENDLEIN, ANDREAS; TUNCABOYLU, DENIZ CEYLANPublication In situ formation of biocompatible and ductile protein-based hydrogels via Michael addition reaction and visible light crosslinking(2023-05-22) Tutar R.; Koken S. Y.; TUNCABOYLU D. C.; Çelebi-Saltik B.; ÖZEROĞLU C.; TUNCABOYLU, DENIZ CEYLANKeratin, a biological polymer with high sulfur content, is the main component of hair, feathers and wool. Human hair is the cheapest natural source of keratin. In this study, an optimized and very effective reduction reaction method was used to obtain keratin from human hair. During this process, the disulfide bridge of keratin was reduced in the presence of sodium sulfide to form free sulfhydryl (thiols) that would act as a strong nucleophile. The results of FTIR spectroscopy, Tricine-SDS-PAGE and MALDI-TOF/MS verified the successful extraction of the reduced human hair keratin. A well-interconnected structure with three-dimensional (3D) scaffolds was prepared using keratin and methacrylated gelatin (GelMA), KeratinGel, for tissue engineering and other biomedical applications. KeratinGel hydrogels were in situ prepared via Michael addition reaction and visible light crosslinking. Two complementary crosslinking reactions were combined to enhance the network structure and provide ductility. With the targeted two-step method, the reactivity of vinyl groups of GelMA to photocrosslinking and thiol groups in keratin to the Michael addition reaction was exploited. Rheological monitoring of the Michael addition reaction was performed for KeratinGel hydrogels in a basic reaction environment at pH 7.4 with a constant concentration of GelMA (10% w/v) and different amounts of reduced human hair keratin (5, 7.5 and 10% w/v) at room temperature. The physical properties, swelling and degradation rates of KeratinGel hydrogels were determined to understand their suitability for tissue regeneration. We finalize that KeratinGel hydrogels would be better in minimally invasive surgeries, soft tissue engineering, especially with in situ gelling features, and favourable for the preparation of complex shapes and applications.Publication Light and Temperature Responsive Injectable Smart Gels with Pluronic and Amphiphilic Copolymers(2022-06-12T00:00:00Z) ALEMDAR, MAHİNUR; CEYLAN TUNCABOYLU, DENİZ; KİRMİÇ COŞGUN, ŞEYMA NUR; KURT, HATİCE KÜBRA; TEMEL, BİNNUR; TUNCABOYLU, DENIZ CEYLAN; TEMEL, BİNNURPublication Autonomic self-healing in covalently crosslinked hydrogels containing hydrophobic domains(2013-11-01T00:00:00Z) Tuncaboylu, Deniz C.; Argun, Aslihan; Algi, Melek Pamuk; Okay, Oğuz; TUNCABOYLU, DENIZ CEYLANSelf-healing hydrogels suffer from low mechanical strength due to their reversible breakable bonds which may limit their use in any stress-bearing applications. This deficiency may be improved by creating a hybrid network composed of a combination of a physical network formed via reversible crosslinks and a covalent network. Here, we prepared a series of hybrid hydrogels by the micellar copolymerization of acrylamide with 2 mol % stearyl methacrylate (C18) as a physical crosslinker and various amounts of N,N--methylenebis(acrylamide) (BAAm) as a chemical crosslinker. Rheological measurements show that the dynamic reversible crosslinks consisting of hydrophobic associations surrounded by surfactant micelles are also effective within the covalent network of the hybrid hydrogels. A significant enhancement in the compressive mechanical properties of the hybrid gels was observed with increasing BAAm content. The existence of an autonomous self-healing process was also demonstrated in hybrid gels formed at low chemical crosslinker ratios. The largest self-healing efficiency in hybrids was observed in terms of the recovered elastic modulus, which was about 80% of the original value. (C) 2013 Elsevier Ltd. All rights reserved.
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