JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS 3 (2010) 203–209 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jmbbm Research paper Thermal behavior and mechanical properties of physically crosslinked PVA/Gelatin hydrogels Yurong Liu a,c , Luke M. Geever b , James E. Kennedy b , Clement L. Higginbotham b , Paul A. Cahill c , Garrett B. McGuinness a,∗ a Materials Processing Research Centre, Dublin City University, Glasnevin, Dublin 9, Dublin, Ireland b Centre of Biopolymer and Biomolecular Research, Athlone Institute of Technology, Dublin Road, Athlone, Ireland c Vascular Health Research Centre, Dublin City University, Glasnevin, Dublin 9, Dublin, Ireland ARTICLE INFO Article history: Received 9 April 2009 Received in revised form 1 July 2009 Accepted 2 July 2009 Published online 14 July 2009 ABSTRACT Poly (vinyl alcohol)/Gelatin hydrogels are under active investigation as potential vascular cell culture biomaterials, tissue models and vascular implants. The PVA/Gelatin hydrogels are physically crosslinked by the freeze-thaw technique, which is followed by a coagulation bath treatment. In this study, the thermal behavior of the gels was examined by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Rheological measurement and uniaxial tensile tests revealed key mechanical properties. The role of polymer fraction in relation to these mechanical properties is explored. Gelatin has no significant effect on the thermal behavior of PVA, which indicates that no substantial change occurs in the PVA crystallite due to the presence of gelatin. The glass transition temperature, melting temperature, degree of crystallinity, polymer fraction, storage modulus (G ′ ) and ultimate strength of one freeze-thaw cycle (1FT) hydrogels are inferior to those of 3FT hydrogels. With coagulation, both 1FT and 3FT hydrogels shifted to a lower value of T g , melting temperature and polymer fraction are further increased and the degree of crystallinity is depressed. The mechanical properties of 1FT, but not 3FT, were strengthened with coagulation treatment. This study gives a detailed investigation of the microstructure formation of PVA/Gelatin hydrogel in each stage of physical treatments which helps us to explain the role of physical treatments in tuning their physical properties for biomechanical applications. c  2009 Elsevier Ltd. All rights reserved. 1. Introduction Poly(vinyl alcohol) (PVA), as a synthetic polymer, is able to form physically crosslinked hydrogels by a variety of methods, such as chemical crosslinking (Nuttelman et al., 2001), irradiation (Schmedlen et al., 2002), or the freeze-thaw technique (Hassan and Peppas, 2000). ∗ Corresponding author. Tel.: +353 1 7005423; fax: +353 1 7005345. E-mail address: garrett.mcguinness@dcu.ie (G.B. McGuinness). PVA hydrogels have been proposed for a number of applications, especially in the biomedical and pharmaceutical areas (Hassan and Peppas, 2000), heart valves (Wan et al., 2002; Jiang et al., 2004), corneal implant (Vijayasekaran et al., 1998), cartilage substitute (Stammen et al., 2001) and arterial phantoms (Chu and Rutt, 1997). The apparent 1751-6161/$ - see front matter c  2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jmbbm.2009.07.001