Chetty, AKovács, JSulyok, ZsMészáros, AFekete, JDomján, ASzilágyi, AVargha, V2012-12-042012-12-042013-01Chetty A, Kovács J, Sulyok Zs, Mészáros A, Fekete J, Domján A, Szilágyi A and Vargha V. 2013. A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology. eXPRESS Polymer Letters, Vol. 7 (1), pp 95-1051788-618Xhttp://www.expresspolymlett.com/http://hdl.handle.net/10204/6391Copyright: This is an Open Access journal. This journal authorizes the publication of the information herewith contained. Published in eXPRESS Polymer Letters, Vol 7(1), pp 95-105.Poly(N-isopropylacrylamide-co-N,N"-methylene-bisacrylamide) (P(NIPAAm-co-MBA)) hydrogels were prepared in water using redox initiator. The copolymer composition at high conversion (> 95%) was determined indirectly by HPLC (high performance liquid chromatography) analysis of the leaching water and directly by solid state 13C CP MAS NMR (cross polarization magic angle spinning nuclear magnetic resonance) spectroscopy of the dried gels, and was found to be close to that of the feed. The effect of cross-linker (MBA) content in the copolymer was investigated in the concentration range of 1.1–9.1 mol% (R:90–10; R = mol NIPAAm/mol MBA) on the rheological behaviour and mechanical strength of the hydrogels. Both storage and loss modulus decreased with decreasing cross-linker content as revealed by dynamic rheometry. Gels R70 and R90 with very low cross-linker content (1.2–1.5 mol% MBA) have a very loose network structure, which is significantly different from those with higher cross-linker content manifesting in higher difference in storage modulus. The temperature dependence of the damping factor served the most accurate determination of the volume phase transition temperature, which was not affected by the cross-link density in the investigated range of MBA concentration. Gel R10 with highest cross-linker content (9.1 mol% MBA) behaves anomalously due to heterogeneity and the hindered conformation of the side chains of PNIPAAm.enPolymer gelsPNIPAAmRheologyMechanical propertiesCopolymer compositionArticleChetty, A., Kovács, J., Sulyok, Z., Mészáros, A., Fekete, J., Domján, A., ... Vargha, V. (2013). A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology. http://hdl.handle.net/10204/6391Chetty, A, J Kovács, Zs Sulyok, A Mészáros, J Fekete, A Domján, A Szilágyi, and V Vargha "A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology." (2013) http://hdl.handle.net/10204/6391Chetty A, Kovács J, Sulyok Z, Mészáros A, Fekete J, Domján A, et al. A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology. 2013; http://hdl.handle.net/10204/6391.TY - Article AU - Chetty, A AU - Kovács, J AU - Sulyok, Zs AU - Mészáros, A AU - Fekete, J AU - Domján, A AU - Szilágyi, A AU - Vargha, V AB - Poly(N-isopropylacrylamide-co-N,N"-methylene-bisacrylamide) (P(NIPAAm-co-MBA)) hydrogels were prepared in water using redox initiator. The copolymer composition at high conversion (> 95%) was determined indirectly by HPLC (high performance liquid chromatography) analysis of the leaching water and directly by solid state 13C CP MAS NMR (cross polarization magic angle spinning nuclear magnetic resonance) spectroscopy of the dried gels, and was found to be close to that of the feed. The effect of cross-linker (MBA) content in the copolymer was investigated in the concentration range of 1.1–9.1 mol% (R:90–10; R = mol NIPAAm/mol MBA) on the rheological behaviour and mechanical strength of the hydrogels. Both storage and loss modulus decreased with decreasing cross-linker content as revealed by dynamic rheometry. Gels R70 and R90 with very low cross-linker content (1.2–1.5 mol% MBA) have a very loose network structure, which is significantly different from those with higher cross-linker content manifesting in higher difference in storage modulus. The temperature dependence of the damping factor served the most accurate determination of the volume phase transition temperature, which was not affected by the cross-link density in the investigated range of MBA concentration. Gel R10 with highest cross-linker content (9.1 mol% MBA) behaves anomalously due to heterogeneity and the hindered conformation of the side chains of PNIPAAm. DA - 2013-01 DB - ResearchSpace DP - CSIR KW - Polymer gels KW - PNIPAAm KW - Rheology KW - Mechanical properties KW - Copolymer composition LK - https://researchspace.csir.co.za PY - 2013 SM - 1788-618X T1 - A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology TI - A versatile characterization of poly(N-isopropylacrylamideco-N,N!-methylene-bis-acrylamide) hydrogels for composition, mechanical strength, and rheology UR - http://hdl.handle.net/10204/6391 ER -